CN108018779A - Concrete construction method under a kind of low temperature difference environment - Google Patents

Abstract

Concrete construction method under a kind of low temperature difference environment provided by the invention, includes successively：The preparation of concrete, the transport of concrete, the tensioning of deformed bar, the binding of reinforcing bar, the pouring of concrete, the maintenance of concrete：Wherein, the tensioning of deformed bar, process conditions are：Before tensioning, 1h is heated to the hydraulic oil in tensioning sump, and jack is preheated；Tensioning selection carries out more than 5 DEG C, in tensioning, is heated under fuel tank, until tensioning is completed；Wherein, the maintenance of concrete uses construction " heating house method ", and process conditions are：Concrete conserves in brooder, and stove or warm-air drier are set in brooder, and temperature control is at 15 40 DEG C, and 7d humid controls are more than 80% before maintenance, and 8 28d humid controls of maintenance are more than 50%.This method technique is simple, easy to operate, can be obviously improved the intensity of concrete, greatly shorten the duration.

Description

Concrete construction method under a kind of low temperature difference environment

Technical field

The invention belongs to technical field of bridge engineering, concrete construction side under more particularly to a kind of low temperature difference environment Method.

Background technology

Continuous rigid frame bridge is without other expansion joints in addition to beam-ends, and driving smooth-going is comfortable, and pier consolidation, structural integrity is good, interior Power is evenly distributed rationally, and anti-seismic performance and bearing capacity are strong, quick construction, is accounted in the bridge on highway of Qinghai-xizang Plateau Region It is one of the popularization bridge type in Qinghai Province from now on according to increasing proportion.

However, the high-pier large-span continuous rigid frame bridge for being located in Hinterland of Qinghai-Xizang Plateau is frequently subjected to low temperature, the big temperature difference (day and night temperature Poor big and annual mean temperature difference is big), the influence of ice and snow, frozen soil and strong wind dry weather, conditions of project natural environment is severe.Complicated weather bar Part special technical barrier is formd to bridge engineering construction, it is necessary to quality of materials, construction technology, construction monitoring etc. into Row special item, proposes the high-pier large-span continuous rigid frame bridge construction control technology of suitable High aititude low temperature difference environmental condition And method, ensure construction quality and safety.

Although the design and construction technique of long-span rigid frame bridge has larger progress, existing pin in recent decades Construction technology research to the continuous rigid frame bridge under low temperature difference environment also achieves certain achievement, but with across footpath The inevitably presence of deviation, big under Qinghai-Tibet High aititude, low temperature, big temperature difference environment constantly in increase and design and construction Across footpath continuous rigid frame bridge still should be noted the problem of following 3 aspects in the construction process：

(1) quality of materials problem

1) concrete is being prepared and transported, needing to control environment temperature in casting process, if temperature is too low, can influence coagulation The mix performance and mobility of soil, so as to influence the intensity of concrete component；2) the shrinkage and creep problem of concrete material.Pier stud No. 0 block that highly (slenderness ratio) and Long span are brought product is increasing, necessarily causes going out for mass concrete and construction joint It is existing；Light high strength concrete using while also bring the negative issue of hydration heat of cement.The thing followed is exactly that high pier is big The contraction of across footpath continuous rigid frame bridge concrete and problem of creeping, this is also a major issue for perplexing Modern Bridge Engineering.

(2) construction technology problem

1) the maintenance control of concrete.Concrete works under varying environment need to take corresponding maintenance control measure.It is blue or green Hiding the big temperature difference environment of low temperature in plateau makes concrete to crack because enduring cold；High solar radiation causes environmental drying, moisture evaporation Rapidly, Surface layer's concrete easily produces crack because of dehydration, therefore, the selection of maintenance measure and performs effectively to concrete-bridge Construction quality have important influence；2) influence of low temperature, the big temperature difference to prestressed stretch-draw.Low temperature environment may cause pre- The irregular working of stress rib tensioning equipment and hydraulic oil, influences the stretch-draw effect and quality of presstressed reinforcing steel；The tensioning time also can It is different from conventional environment because of the influence of low temperature.Therefore, the selection and the setting of tensioning time of prestress tensioning equipment, it is also desirable to Cause the attention of long-span rigid frame bridge work progress under low temperature difference environment.

(3) construction monitoring problem

1) low temperature, the big temperature difference are to linear, absolute altitude influence.Except cantilever construction itself bring complexity beam body absolute altitude and The pairings such as concrete shrinkage deformation, change in displacement and internal force that alignment control demand, low temperature and the big temperature difference may be brought is uneven Imperial technology and pier shaft degree control propose the challenge of bigger, and therefore, the construction of continuous rigid frame bridge should also be noted that low temperature and big Influence of the temperature difference to bridge linear, monitors absolute altitude, deformation and the stability status of bridge, to be protected by adjusting construction technology in time Hinder the linear of continuous rigid frame bridge, improve construction quality；2) Bridge Design and the stress-deviation in construction.Although Long span in advance should Power concrete continuous rigid structure bridge uses the model of Reinforced Concrete Materials in the design process, its structure size is also relatively small. And the load level of actual bridge test is relatively low, various factors causes inclined in the presence of being difficult to overcome between result of the test and computation model Difference, the distribution of actual internal force have certain difference with analysis result.In addition, the use of Cantilever Construction Method so that bridge The internal force distribution of structure is complex.Therefore, consider from engineering safety angle, improve the construction monitoring of long-span rigid frame bridge Ability, by the way that the finishing analysis of a large amount of first hand field measurement data are obtained with the most intuitively state of bridge load, stress, Selection, improvement so as to guiding construction technique, by stress level control within prescribed limit, it is ensured that the security of engineering.

The content of the invention

Technical problem：The defects of in order to solve the prior art, the present invention provides coagulation under a kind of low temperature difference environment Native construction method.

Technical solution：Concrete construction method under a kind of low temperature difference environment provided by the invention, includes successively：Coagulation Preparation, the transport of concrete, the tensioning of deformed bar, the binding of reinforcing bar, the pouring of concrete, the maintenance of concrete of soil：

Wherein, the tensioning of deformed bar, process conditions are：Before tensioning, the hydraulic oil in tensioning sump is heated 1h, and jack is preheated；Tensioning selection carries out more than -5 DEG C, in tensioning, is heated under fuel tank, until tensioning is complete Into；

Wherein, the maintenance of concrete uses construction " heating house method ", and process conditions are：Concrete conserves in brooder, in brooder Stove or warm-air drier are set, and temperature control 7d humid controls before 15-40 DEG C, maintenance more than 80%, conserve 8-28d humidity controls System is more than 50%；Steel form wraps up concrete, then insulating layer is set outside steel form, form removal after 24h, immediately with modeling after form removal Expect that cloth, blanket or tarpaulin parcel conserve 28 days.

As an improvement, the concrete is at least made of the component of following parts by weight：Cement, coarse aggregate, fine aggregate, mineral Admixture, additive；In the concrete,

Gel rubber material dosage is 350kg/m³~500kg/m³, it is preferable that gel rubber material dosage is 400kg/m³~500kg/ m³, it is highly preferred that C30 strength grade concrete gel materials dosage is 380kg/m³, C40 strength grade concrete gel materials Dosage is 420kg/m³, C50 concrete gel materials dosage is 500kg/m³；

Sand coarse aggregate ratio is 33-42%, it is preferable that sand coarse aggregate ratio 39-41%, it is highly preferred that sand coarse aggregate ratio is 39%；

Mineral admixture volume is 0-30%, it is preferable that mineral admixture volume is 0-15%, it is highly preferred that mineral are mixed It is 15% to close material volume；

The volume of additive is 1.0~1.4%, preferably 1.0%；

Water-cement ratio is 0.34-0.48, it is preferable that water-cement ratio 0.34-0.40, it is highly preferred that C30 water-binder ratios are 0.45, C40

The water-cement ratio of concrete is that 0.40, C50 water-binder ratios are 0.34.

As an improvement, the cement is portland cement, ordinary portland cement, KS- slag cements, FS- pulverized fuel ash cements, preferably KS- slag cements；The fineness of the cement is 280~402m²/ kg, preferably 335~402m²/kg。

As a further improvement, the particle diameter of the coarse aggregate, between 20-40mm, coarse aggregate elongated particles are 5- 14%.

As a further improvement, the particle diameter of the fine aggregate, between 0.16~5mm, its modulus of fineness is 2.5-3.2, is contained Mud amount is 1.5-3.5%, it is preferable that modulus of fineness 3.0, clay content 2%.

As a further improvement, the mineral admixture for flyash, graining blast-furnace cinder micro-powder, silicon ash, zeolite rock powder, One or more in agstone, natural volcanic ash, preferably Class F fly ash or high-calcium fly ass, more preferably high calcium fine coal Ash, most preferably I grade high-calcium fly ass.

As a further improvement, the additive includes water-reducing agent, adjustable solidification agent, waterproofing agent, one kind in air entraining agent or several Kind；The water-reducing agent includes polycarboxylate water-reducer, preferably naphthalene water reducer, polycarboxylate water-reducer；The volume of the water-reducing agent is 1.0~1.4%, preferably 1.0%.

Beneficial effect：Concrete construction method technique is simple under low temperature difference environment provided by the invention, easy to operate, The intensity of concrete can be obviously improved, greatly shortens the duration.

Brief description of the drawings

Fig. 1-1 is the variation diagram of concrete drying shrinkage under different temperatures；Fig. 1-2 is concrete creep degree under different temperatures Variation diagram；Fig. 1-3 is the variation diagram of concrete drying shrinkage under different humidity；Fig. 1-4 is concrete creep under different humidity The variation diagram of degree；Fig. 1-5 is concrete crushing strength development figure under different conservation systems；Fig. 1-6 is 3d mean temperatures and resistance to compression The graph of a relation of intensity；Fig. 1-7 is the graph of a relation of 7d mean temperatures and compression strength；Fig. 1-8 is 14d mean temperatures and pressure resistance The graph of a relation of degree；Fig. 1-9 is the graph of a relation of 28d mean temperatures and compression strength；Fig. 1-10 is 3d medial humidities and compression strength Graph of a relation；Fig. 1-11 is 7d medial humidities and the graph of a relation of compression strength；Fig. 1-12 is 14d medial humidities and compression strength Graph of a relation；Fig. 1-13 is 28d medial humidities and the graph of a relation of compression strength；Elongation percentage error when Fig. 1-13 is-16 DEG C Each section distribution map；Each section distribution map of elongation percentage error when Fig. 1-14 is-4 DEG C；Elongation misses when Fig. 1-15 is 6 DEG C Poor each section distribution map of percentage；Each section distribution map of elongation percentage error when Fig. 1-16 is 19 DEG C；Fig. 1-17 is difference Temperature Regression equation oil pressure meter reading estimates load reading figure；Fig. 1-18 pushes away for different temperature Regression equation oil pressure meter readings Constant load reading.The graph of a relation of Fig. 2-1 difference cement type concrete crushing strengths and curing age；Fig. 2-2 difference cement product Kind concrete carbonization time and carbonation depth graph of a relation；Influence of Fig. 2-3 cement types to ion penetration resistance of concrete energy Figure；Influence figure of Fig. 2-4 cement types to concrete antifreezing performance；Fig. 2-5 difference cement granules fineness concrete crushing strengths With the graph of a relation of curing age；Fig. 2-6 difference cement fineness concrete carbonization times and carbonation depth graph of a relation；Fig. 2-7 cement Influence figure of the fineness to ion penetration resistance of concrete energy；Influence figure of Fig. 2-8 cement fineness to concrete antifreezing performance；Figure The graph of a relation of 2-9 difference flyash concrete compression strength and curing age；Fig. 2-10 difference flyash concrete carbonization times With carbonation depth graph of a relation；Influence figure of Fig. 2-11 difference flyash to ion penetration resistance of concrete energy；Fig. 2-12 is different Influence figure of the flyash to concrete antifreezing performance；Fig. 2-13 difference quality flyash concrete compression strength and curing age Graph of a relation；Fig. 2-14 difference quality flyash concrete carbonization times and carbonation depth graph of a relation；Fig. 2-15 quality of fly ash To the influence figure of ion penetration resistance of concrete energy；Influence of Fig. 2-16 difference quality flyash to concrete antifreezing performance Figure；Fig. 2-17 difference concrete crushing strengths of water-reducing agent and the graph of a relation of curing age；Fig. 2-18 difference water-reducing agent concrete Carbonization time and carbonation depth graph of a relation；Influence figure of Fig. 2-19 difference water-reducing agents to ion penetration resistance of concrete energy；Figure Influence figure of the 2-20 differences water-reducing agent to concrete antifreezing performance；Fig. 2-21 water-reducing agents volume influences to scheme on concrete flowability； Fig. 2-22 water-reducing agents volume influences to scheme on different curing age concrete crushing strengths；Fig. 2-23 water-reducing agent volumes are to concrete Carbonization time and carbonation depth graph of a relation；Influence figure of Fig. 2-24 water-reducing agents volume to ion penetration resistance of concrete energy；Figure Influence figure of the 2-25 water-reducing agents volume to concrete antifreezing performance；Influence of Fig. 2-25 water-reducing agents volume to concrete antifreezing performance Figure；Influence figure of Fig. 2-26 moduluss of fineness to the C30 slumps；Influence figure of Fig. 2-27 moduluss of fineness to C30 concrete strengths；Figure Influence figure of the 2-28 moduluss of fineness to C50 concrete strengths；Influence figure of Fig. 2-29 moduluss of fineness to the C50 slumps；Fig. 2-30 Influence figure of the clay content to C30 concrete strengths；Influence figure of Fig. 2-31 clay contents to the C30 slumps；Fig. 2-32 clay contents pair The influence figure of C50 concrete strengths；Influence figure of Fig. 2-33 clay contents to the C50 slumps；Fig. 2-34 water-cement ratios are to concreter Make the influence figure of performance；Influence figure of Fig. 2-35 water-cement ratios to concrete crushing strength；Fig. 2-36 water-cement ratios resist concrete 28d Roll over the influence figure of intensity；Influence figure of Fig. 2-37 water-cement ratios to concrete dynamic modulus of elasticity；Fig. 2-38 water-cement ratios are to agent on crack resistance of concrete The influence figure of fragility energy；Influence figure of Fig. 2-39 water-cement ratios to concrete antifreezing performance；Fig. 2-40 gel material contents are to coagulation The influence figure of native compression strength；Influence figure of Fig. 2-41 gel material contents to concrete dynamic modulus of elasticity；Fig. 2-42 gelling materials Expect influence figure of the dosage to crack-resistant performance of concrete；Influence figure of Fig. 2-43 gel material contents to concrete antifreezing performance；Figure C50 concrete crushing strength figures under 2-44 difference conservation systems；C50 concrete flexural strengths under Fig. 2-45 standard curing systems Figure；Concrete dynamic modulus of elasticity development figure under Fig. 2-46 difference doping quantity of fly ash；Fig. 2-47 flyash is to crack-resistant performance of concrete Influence figure；Influence figure of Fig. 2-48 flyash to concrete antifreezing performance；Shadow of Fig. 2-49 sand coarse aggregate ratios to concrete crushing strength Ring figure；Influence figure of Fig. 2-50 sand coarse aggregate ratios to concrete flexural strength；Influence figure of Fig. 2-51 sand coarse aggregate ratios to concrete dynamic modulus of elasticity； Influence figure of Fig. 2-52 sand coarse aggregate ratios to crack-resistant performance of concrete；Influence figure of Fig. 2-53 sand coarse aggregate ratios to concrete antifreezing performance；Fig. 2-54 Influence figure of the water-cement ratio to self-constriction；Fig. 2-55 ratio of muds are to the dry influence figure shunk；Fig. 2-56 water-cement ratios are to concrete Xu The influence figure of variation；Influence figure of Fig. 2-57 flyash to self-constriction；Fig. 2-58 flyash is to the dry influence figure shunk；Fig. 2- Influence figure of 59 doping quantity of fly ash to concrete creep；Influence figure of Fig. 2-60 sand coarse aggregate ratios to concrete self-shrinkage；Fig. 2-61 sand coarse aggregate ratios Influence figure to concrete drying shrinkage；Influence figure of Fig. 2-62 sand coarse aggregate ratios to concrete creep degree.

Embodiment

1st, working performance：Press《Standard for test methods of properties of ordinary concrete mixture standard》(GB/T 50080-2002) is carried out Concrete test.The slump is tested using slump cone, and is observed concrete and sticked poly- property and water-retaining property.

2nd, mechanical property：According to《Standard for test methods of mechanical properties of ordinary concrete》(GB/T 50081-2002) is carried out Concrete anti-compression performance study.

Using 100 × 100 × 100mm test specimen pouring moldings, standard conditions maintenance is carried out after form removal, test concrete is corresponding Age (3d, 7d and 28d) compression strength.

Using 150 × 150 × 150mm test specimen pouring moldings, standard conditions maintenance is carried out after form removal, test concrete is corresponding The compression strength of age, flexural strength, dynamic modulus of elasticity.

This experiment measures the dynamic modulus of elasticity of concrete using ultrasound.Sample dimensions are 100mm × 100mm × 400mm's Prism.Test specimen points 5 groups, every group of 4 test specimens, totally 20 test specimens.Transducer is lightly compressed upon two end faces of test specimen, contact surface It is couplant to apply one layer of butter, is converted to the velocity of sound by following formula during the sound that will be measured, compares Determination of Dynamic Elastic Modulus by comparing the velocity of sound Change：In formula：Vr --- velocity of ultrasonic sound, km/s；Between l --- ultrasonic throw, i.e. two transducer radiating surfaces The length of test specimen, mm；The time of t --- ultrasonic propagation, us.

3rd, endurance quality：The experimental study of this durability performance mainly includes：Carbonation properties, resisting chloride ion penetration performance and frost resistance Energy.According to《Standard for test methods of longterm performance and durability of ordinary concrete standard》Carry out corresponding Experimental Investigation on Durability.

(1) carbonization test：Concrete sample size is 100mm × 100mm × 100mm, is placed in (carbon dioxide in carbonization case It is 20 ± 5 DEG C that concentration, which is maintained at 20 ± 3%, relative humidity and controls in 70 ± 5%, temperature), to corresponding carbonization age (3d, 7d, 14d and 28d) when, take out test specimen and two halves are split on rock cutter, in the 1% phenolphthalein alcohol of surface spraying rived Solution, non-carbonized region can show red, and measurement color change interval length is carbonation depth.

(2) resisting chloride ion penetration is tested：This experiment uses the quick chloride permeability test methods of RCM, its concrete operations step first Suddenly it is：

1) test specimen section, full water：Ф 100mm × 200mm test specimens are cut into the 2 of identical size from centre with rock cutter Part, the test specimen that a height is 50mm is then respectively cut from two parts, 3 test specimens without forming surface are left, using beating Grinding machine grinds off corner angle, and is put into vacuum in SBS type concrete intelligent vacuum water conservation machines and satisfies water 1 day.

2) quick chloride permeability：First test specimen after full water is put into rubber drum during experiment, and with iron hoop banding, is confirmed not After leak, it is put into test flume；10%NaCl solution is injected outside rubber drum, injects 0.3mol/L NaOH solutions in bucket, Test specimen two ends are put into electrode in rubber drum, plus DC voltage, can be shown on RCM-A types chloride diffusion coefficient analyzer at this time Initial series current, experiment complete needed for test specimen and electrolyte initial temperature, during off-test, anolyte final temperature meeting Shown on instrument.

3) penetration depth measures：Take out test specimen and two halves are split on pressure testing machine, in the surface spraying rived 0.1mol/L AgNO₃Solution, can be observed white silver nitride precipitation, and measurement colour developing line of demarcation is averaged with a distance from bottom surface As colour developing depth.

4) chloride diffusion coefficient calculates：Chloride diffusion coefficient is calculated by following formula：

In formula：D_RCM--- chloride diffusion coefficient (m²/s)；T --- anolyte is initial and final temperature average value (K)；H --- height of specimen (m)；x_d--- chloride diffusion depth (m)；T --- the energizing test time (s)；α --- auxiliary becomes Amount, is equal to

4th, cracking resistance

Flat tests are the test methods for evaluating concrete (or mortar) early-age plastic cracking performance.Experimental evidence is built Material professional standard《Cement mortar cracking resistance test method》(JC/T 951-2005) is carried out.

The template bottom of experiment is five-ply board, and circumferential side frame is made of hardwood, and template bottom and circumferential side frame use wood snail Nail and white glue hydropexis are good；Dead size (i.e. sample dimensions) in template：Long 910mm ± 3mm, width 600mm ± 3mm, high 20mm ± 1mm；Template bottom is lined with two layers of plastic thin films, to reduce influence of the bed die to test specimen contraction distortion；Template surrounding, bottom should be protected Hold formation state, no warpage, the phenomenon without pit；The frame of a diameter of 8mm plain bars, the peripheral ruler of frame are placed in template Very little (including reinforcing bar)：Four vertical reinforcement terminations are respectively welded in long 880mm ± 3mm, width 570mm ± 3mm, frame corner, Steel bar end is 6mm from the height of template bottom；Steel bar framework allows to reuse, but steel bar framework should keep cleaning thousand it is net, Do not deform significantly, no warpage, the phenomenon without desoldering, frame should be in approximately the same plane, when being used so that guarantee is next not Expose mortar surface.

(1) anti-cracking index

This Experimental Evaluation foundation is used as using the crack in confining region.Crack is divided into by Pyatyi according to the width in crack, often Level-one corresponds to a weighted value (as shown in table 12), the length of each crack has been multiplied by corresponding weighted value, then be added Carry out obtained summation and be known as crack index W, the cracking degree of mortar is represented with this.

The evaluation of 12 tablet of table cracking experiment

Crack index is calculated as follows in terms of mm：W=∑s (A_i×l_i)；

In formula：W --- crack index, unit millimeter (mm)；A_i--- weighted value；l_i--- fracture length.

(2) the crack occurrence gross area

The crack occurrence gross area is with mm²Meter, is calculated as follows：Acr=∑s (w_i×l_i)；

In formula：A_cr--- area of cracks, unit square millimeter (mm²)；w_i--- fracture width；l_i--- fracture length.

5th, anti-freezing property：This antifreezing test freezes method using fast, using the prism test specimen of 100mm × 100mm × 400mm, Every group of 3 pieces of test specimen.Concrete antifreezing performance is characterized with relative dynamic elastic modulus after concrete sample Frozen-thawed cycled 300 times.

1 concrete structure of embodiment conserves control technology research

1st, influence of the humiture to concrete shrinkage and creep

(1) influence of the temperature to concrete shrinkage and creep

Fig. 1-1 and 2 is different temperatures lower age to concrete drying shrinkage and the influence crept.From the figure, it can be seen that With the rise of curing temperature, concrete drying shrinkage and creeping all increases.Drying, which is shunk, when wherein 20 DEG C of temperature compares 5 DEG C increases Add 8% or so, and creep degree when 35 DEG C of temperature compares 5 DEG C then improves 20%, it is seen that contraction of the temperature for concrete All significantly affected with creeping.This is because when temperature raises, the speed of concrete dehydration is accelerated, therefore it shrinks and adds It hurry up, creep in addition, having frequently included dry caused drying in creeping, therefore creep also with the rise of temperature and increase, And it is related with the movement of water in cement mortar to creep, the rise of temperature reduces the viscosity of cement mortar, therefore also exacerbates coagulation Soil is crept.

(2) influence of the humidity to concrete shrinkage and creep

Fig. 1-3,4 are different humidity lower ages to concrete drying shrinkage and the influence crept.First, humidity is bigger, mixes The speed of solidifying soil dehydration is slower, and the dry contraction nature of concrete is smaller.In addition, creeping for the bigger concrete of humidity is also smaller, There is research table 1- bright, what the concrete in drying occurred creeps than the concrete under constant drying or moisture state The amount of creeping it is big, 2-3 times crept when can reach relative humidity 100% during relative humidity 50%.And humidity in Fig. 1-4 Concrete creep degree when 40% opposite 60% adds 15% or so.This is because humidity is bigger, the evaporation capacity for adsorbing water is cured Small, the degree of hydration of cement is higher, and the density of cement gel body is higher, and concrete structure is also more closely knit, thus its shrink and Creep also smaller.

2nd, influence of the different conservation systems to concrete shrinkage and creep performance

(1) concrete structure conserves control technology development test scheme under low temperature difference environment

For this subitem based on laboratory test, it is research object to select C50 grade concretes, carries out different maintenance methods respectively The affecting laws research of lower concrete shrinkage deformation and endurance quality, proposes to improve endurance quality and meets supporting for construction period Shield system.

Since curing temperature is excessive, although can accelerate the condensation hardening process of cement, numerous studies table 1- is bright, and high temperature is supported Under the conditions of shield, the short texture of final concrete, porosity increase, i.e., have endurance performance of concrete detrimental effect, therefore, The maximum temperature considered in this conservation system is 35 DEG C.The investigation content of conservation system research is as shown in table 1-1, in inspection target Include concrete shrinkage deformation behavior and endurance quality index.

Table 1-1 conservation systems influence testing program to endurance performance of concrete

(2) influence of the different conservation systems to concrete strength

Table 1-2 is the compression strength data using concrete under eight kinds in table 1-1 different conservation systems.

Concrete crushing strength under table 1-2 difference conservation systems

It can be seen that, it is continuously improved from table 1-2 and Fig. 1-5 with the increase concrete strength of age, and different maintenances The concrete strength rule of development is different under system.Using the Cure-S groups of standard curing, concrete 28d compression strength 60.2MPa, and it is very slow using natural curing Cure-N groups strength development, and 28d compression strength is only 47.0MPa, Wu Fada To design strength requirement.In contrast, using construction " heating house method " concrete strength can be caused substantially to increase, identical curing time When compression strength improve 10-15% compared to regenerative process, it is and little with standard curing environment difference, this is because in highlands Only with regenerative process, the humiture (especially humidity) needed for concrete early hydration can not fully ensure that, and be added using brooder Heat is capable of providing more preferable care environments.And steam-cured Cure-5, Cure-6 group is used, concrete sample early strength Rising is obvious, and 3d can reach more than the 80% of 28d intensity, but later strength increase is slow, and 28d compression strength compares mark Quasi- maintenance is low all the better, it is seen that steam curing is very big on the influence of concrete early curing, has on the contrary to later strength certain negative Face is rung.In addition, concrete curing 7d compares intensity with 14d and is not much different under identical care environments, it is seen that the maintenance of early period is non- It is often important.

(3) influence of the different conservation systems to concrete durability

Table 1-3 is impermeability, the anti-freezing property index of concrete under different conservation systems.

Concrete durability under table 1-3 difference conservation systems

It can see from table 1-3, similar rule are presented in the impermeability of concrete and anti-freezing property under different conservation systems Rule.Standard curing Under Concrete endurance quality is best, and natural curing Under Concrete endurance quality is worst.Contrast it From the point of view of his conservation system, construction " heating house method " maintenance effect is preferable, is differed when especially Cure-4 groups conserve 28d with standard curing Less, the endurance quality of concrete is relatively poor when using regenerative process and steam curing.

(4) influence of the different conservation systems to concrete shrinkage

Table 1-4 is the rate of self-contraction of concrete, drying shrinkage under different conservation systems.

Concrete shrinkage performance under table 1-4 difference conservation systems

It can see from table 1-4, each group concrete sample self-constriction is compared, standard curing and regenerative process, construction " heating house method " It is not much different, and concrete self-shrinkage is relatively large under steam curing environment, this is probably because the higher maintenance of steam curing Caused by temperature.And from the point of view of contrasting 28d drying contractions, steam curing group and standard curing group difference are little, this is because steam is supported Early strength of concrete quickly forms under retaining ring border, and early strength is higher, therefore early-age shrinkage is also smaller.And coagulation under regenerative process Soil shrinks increase, during construction " heating house method " drying shrink low all the better, during identical curing time, as Cure3 with Cure4 compares accumulation of heat The Cure1 and Cure2 of method reduce 10% or so.Early curing duration directly influences the dry of concrete as can be seen here Dry contraction, curing time is longer, and the dry contraction of concrete is smaller.

(5) influence of the different conservation systems to concrete creep

Table 1-5 is the 180d creep degrees and Creep Coefficient of concrete under different conservation systems.

Concrete creep performance under table 1-5 difference conservation systems

It can see from table 1-5, using the maximum of creeping of natural curing Cure-N groups, comparison with standard maintenance group adds 27.2%, comparison with standard of creeping when being conserved using regenerative process, construction " heating house method " maintenance increased, and the time of maintenance early period gets over It is short, creep bigger, maintenance 7d relatively conserves 28d and adds about 6-8%.And use two kinds of regenerative process, construction " heating house method " conservation systems When creeping for concrete be not much different, and be increased slightly when curing time is identical compared to standard curing.

And compare Cure5, Cure6 of steam curing group it can be found that the steam curing time is longer, creep bigger on the contrary, This is probably because steam-cured temperature is higher (commonly reaching more than 50 DEG C), and concrete aquation too fast in early days causes it Hydrated product can not preferably fill its internal structure so that the density inside concrete structure is bad on the contrary, and conserves temperature When spending relatively low, aquation is slower, and inside concrete micro-structure can be formed preferably, and structure density is more preferable on the contrary.Therefore Being risen using steam curing for concrete structure early strength has good effect, but temperature excessive (should not should not surpass 50 DEG C are crossed, general 35-40 DEG C or so desirable), and the time conserved is unsuitable long.

3rd, temperature influences research

Table 1-6 is the monitoring data of preceding 28d temperature under different conservation systems.

Preceding 28d temperature monitorings data under table 1-6 difference conservation systems

Mean temperature and intensity data during different larval instar under table 1-7 difference conservation systems

It can see from table 1-7 and Fig. 1-6~1-9, when curing temperature is relatively low, the compression strength of concrete each age is equal It is relatively low, or even it is unable to reach the requirement of design strength.And more above-mentioned four width picture can see, maintenance temperature when 3d, 7d age Degree is larger with the positive correlation of compression strength, and overall trend is that curing temperature is higher, and concrete crushing strength is also bigger；And arrive When 14d, 28d age, each data point distribution relatively dissipates, without evident regularity, concrete when being only 10 DEG C or so except curing temperature Bulk strength is relatively low, from the point of view of remaining each group, after maintenance mean temperature reaches 15 DEG C, the positive correlation of temperature and intensity become compared with Small, the discreteness of data becomes larger.

4th, relative humidity influences research

Table 1-8 is the monitoring data of preceding 28d humidity under different conservation systems.

Preceding 28d humidity detections data under table 1-8 difference conservation systems

Medial humidity and intensity data during different larval instar under table 1-9 difference conservation systems

It can see from table 1-8, table 1-9 and Fig. 1-10~1-13, during age 3d, 7d, each data point distribution relatively has rule Rule, humidity and intensity positive correlation are larger, and maintenance humidity is bigger, and concrete strength is higher；And in age 14d, 28d, individually Data point deviation is larger, and data point relative humidity in addition disclosure satisfy that positively related relation substantially with compression strength.

Comprehensive analysis, from the perspective of the selection of highlands concrete curing humiture, the humiture of early curing is non- Often important, especially preceding 7d, will directly influence the development of concrete strength.From the point of view of curing temperature, its value should not be excessive, but Be also unsuitable too low, otherwise will all influence the development of late strength of concrete, generally from the point of view of conserve mean temperature not preferably less than 15 DEG C, early curing can use 15-40 DEG C；Maintenance humidity is then the higher the better, not only contributes to the development of concrete strength, and Be conducive to be lifted its endurance quality, early period maintenance humidity not medial humidity not preferably less than 50% preferably less than in 80%, 28d.Compare From the point of view of, the importance of curing temperature is less than the humidity of maintenance, and the raising of maintenance humidity is conducive to later strength before concrete Overall lifting, and the raising of temperature is then the lifting for being more advantageous to concrete intensity early period.

2 low temperature difference environment lower prestress Construction Control research of embodiment

1st, the working performance under hydraulic oil low temperature

Following table is to test its dynamic viscosity data at different temperatures using different cultivars hydraulic oil.Thus table as it can be seen that Kinematic viscosity will greatly improve normal hydraulic oil at low temperature, its condensation point has just been basically reached less than -18 DEG C, and use Low Temperature Liquid During pressure oil, as the trend substantially risen is presented in the attenuating dynamic viscosity of temperature.It can be seen that hydraulic oil needs to select at low ambient temperatures Low temperature hydraulic oil, and the working performance of hydraulic oil will be entirely different than also with normal temperature phase under subzero temperature.Table 1-10 is without species Hydraulic oil kinematic viscosity at different temperatures data, therefrom it can be seen that, temperature reduces, and the kinematic viscosity of hydraulic oil is obvious Increase, during using normal hydraulic oil, even its condensation point has been arrived when temperature is less than -18 DEG C.

Dynamic viscosity (mm under table 1-10 difference hydraulic oil different temperatures²/s)

Hydraulic oil kind	-40℃	-25℃	-18℃	-10℃	0℃
						Commonly -1	-	-	3146	1907	536
Low temperature -2	-	1862	1324	718	283
						Low temperature -3	2948	1308	879	462	222

2nd, sensitiveness of the tensioning equipment to temperature

Hydraulic oil stickiness increase during low temperature, flowage friction coefficient increases in oil pump, jack when reaching same pressure value Pulling force often when demarcating not as it is big.This is because the calibration of jack is generally carried out in room temperature, when winter temperature reduces, Hydraulic oil becomes sticky, has an impact to the reading of oil meter, deviates calibration curve.It is that no several units carry out in practice of construction Calibration under low temperature, generally can be before tensioning to the hydraulic pressure in tensioning sump in order to ensure construction speed and tensioning quality Oil is heated, and or so general 1 hour before tensioning work starts is heated, and carries out preheating operation to jack. Heated in tensioning under fuel tank, until tensioning is completed.3rd, temperature and tensioning time stretch tension stress and presstressed reinforcing steel The influence of long value

As described above, the change of temperature will directly influence the performance of hydraulic oil, so that the normal work to tensioning equipment Make to produce certain influence.The shadow of temperature during it is therefore desirable to study tensioning for tension stress and Extension Values of Prestress Reinforcements Ring.Table 1-11 is that the steel strand wires of tensioning same size 100, it is extended when prestressed stretch-draw is carried out under varying environment temperature It is worth distribution situation of the percentage error in each section.Temperature is inquired into for Extension Values of Prestress Reinforcements by comparing the distribution situation Influence.

Extension Values of Prestress Reinforcements during 100% tentioning stroke under table 1-11 difference temperature

The distribution situation system in each section of elongation percentage error when Fig. 1-13~1-16 is tensioning under different temperature conditions Meter, can significantly see, when temperature is relatively low (- 16 DEG C), elongation percentage error negative section ratio is substantially more (87%), positive number section is less (13%), and such as (- 6~-4) this grade of accounting reaches 30%, (- 4~-2) then accounting 37%；Temperature For -4 DEG C when, negative section accounting 64%, positive number section accounting 36%, and as temperature raises, each section of elongation percentage error Distribution it is more average, positive negative accounting difference is smaller, and in normal distribution shape, at such as 6 DEG C, 19 DEG C, each section distribution is in obvious Centre is more, form that both ends are few.It can be seen from the above that relatively low temperature will influence the elongation of prestressed stretch-draw to a certain extent Error is measured, temperature is lower, and elongation is relatively less than normal, or even reaches the limit of elongation code requirement soon.And temperature is timing Tensioning is normal.It is therefore proposed that temperature is unsuitable too low during tensioning, should generally select to carry out tensioning in temperature for timing, to ensure tensioning Quality.

For influence of the research temperature to stretching force, three different temperature are selected to carry out tensioning equipment jack regression equation Calibration.

Jack demarcates regression equation under table 1-12 difference temperature

Table 1-13 difference temperature Regression equation oil pressure gauge 1- readings estimate load reading

Can see from table 1-12, the regression equation of jack is different under different temperature, and by table 1-13 and Fig. 1-17 can see, and temperature is lower, and when oil pressure gauge 1- readings are identical, the load reading of presumption is smaller.When stretching force is smaller Influence of the temperature to stretching force is little, and the higher influence of stretching force is then bigger, by taking oil pressure gauge 1- readings 40MPa as an example, at 20 DEG C Load reading 5534.0kN, and load reading 5454.3kN at -16 DEG C, compared to reducing 1.44%.The reduction of actual stretching force The reduction of Extension Values of Prestress Reinforcements certainly will be also resulted in.

It can be seen from the above that carry out that during prestressed stretch-draw tension stress and elongation can be influenced to a certain extent under subzero temperature, especially It is when temperature is very low.Therefore, when carrying out prestressed stretch-draw on plateau, should avoid constructing at a lower temperature, especially When temperature is less than subzero 10 DEG C, otherwise the calibration under low temperature is preferably carried out to jack, to avoid actual tension stress Construction quality hidden danger caused by deficiency.

In addition, the difference of tensioning time certainly will influence tension stress and Extension Values of Prestress Reinforcements, especially for plateau Area, the four seasons temperature difference is big, and Various Seasonal tensioning is not only related to presstressed reinforcing steel (steel strand wires) property of itself, is also relate to tensioning The working performance of equipment hydraulic oil, so as to directly influence tension stress and elongation.Therefore prestressing force is carried out in the winter time During drawing, it is proposed that the temperature higher period carries out tensioning (12 noon to 6 pm) in selecting one day, avoids night or gas Tensioning when temperature is relatively low；And should then select to carry out tensioning daytime in season in spring and autumn tensioning, night tensioning is avoided as far as possible, to ensure to open The quality of drawing.

In summary：

1st, with the rise of curing temperature, concrete drying shrinkage and creeping all increases；Humidity is bigger, concrete dehydration Speed is slower, and the dry contraction nature of concrete is smaller.In addition, creeping for the bigger concrete of humidity is also smaller；

2nd, for highlands prestressed structure, the early strength of concrete can be obviously improved using steam curing, greatly Shorten the construction period greatly, but the temperature conserved should not be too high, otherwise not only influences the development of later strength, can also be to a certain extent Influence concrete durability, it is proposed that general 35-40 DEG C or so desirable no more than 50 DEG C；For highlands concrete curing, from Intensity and the analysis of endurance quality index comprehensive, the effect of construction " heating house method " are better than regenerative process；

3rd, from the perspective of the selection of highlands concrete curing humiture, the humiture of early curing is extremely important, Especially preceding 7d, will directly influence the development of concrete strength.From the point of view of curing temperature, its value should not be excessive, but also not It is preferably too low, otherwise will all influence the development of late strength of concrete, generally from the point of view of conserve not preferably less than 15 DEG C of mean temperature, it is early Phase maintenance is 15-40 DEG C desirable；Maintenance humidity is then the higher the better, not only contributes to the development of concrete strength, and is conducive to Lift its endurance quality, early period maintenance humidity not medial humidity not preferably less than 50% preferably less than in 80%, 28d.From the point of view of comparing, support The importance of shield temperature is less than the humidity of maintenance, and the entirety that the raising of maintenance humidity is conducive to later strength before concrete carries Rise, and the raising of temperature is then the lifting for being more advantageous to concrete intensity early period；

4th, the height of temperature will directly influence the working performance of hydraulic oil for lifting jacks, and temperature reduces, and kinematic viscosity is significantly Improve.It is bright to study table 1-, carries out that during prestressed stretch-draw tension stress and elongation can be influenced to a certain extent under subzero temperature, especially It is when temperature is very low.Therefore, plateau carry out prestressed stretch-draw when, should avoid constructing at a lower temperature, especially when When temperature is less than subzero 10 DEG C, otherwise suggesting carrying out jack the calibration under low temperature, to avoid actual tension stress Deficiency causes the quality of stretching construction.And highlands winter carry out prestressed stretch-draw when, it is proposed that selection one day in temperature compared with The high period carries out tensioning (12 noon to 6 pm)；And should then select to carry out tensioning daytime in season in spring and autumn tensioning, Night tensioning is avoided as far as possible, to ensure the quality of tensioning.

3 raw material key index experimental study of embodiment

First, influence of the cement to concrete performance

1st, cement type

(1) cement type is to working performance of concrete and Effect on Mechanical Properties

Concrete mix and working performance are as shown in table 2-1, and mechanical performance of concrete is as shown in Fig. 2-1.

Table 2-1 concrete mixs (note：S- neat portland cements, PS- ordinary portland cements, KS- slag cements, FS- flyash Cement)

It can see from table 2-1, when the slump is identical, ordinary portland cement (PS) admixture dosage is for up to 1.4%, slag water Mud (KS), pulverized fuel ash cement (FS), admixture dosage 1.2%-1.3%, this illustrates to contain in slag cements, pulverized fuel ash cement Superfined flyash and slag micropowder have certain water-reduction, have when admixture dosage is smaller in the case of identical water consumption larger mixed The solidifying soil slump.

Different cement type mechanical performance of concrete ongoing change are as shown in Fig. 2-1, and concrete strength is pure during 7d ages Portland cement>Ordinary portland cement>Slag cements>Pulverized fuel ash cement, Slag concrete intensity is higher than pure with age during 28d Portland cement intensity, fly ash cement concrete intensity is minimum, and pulverized fuel ash cement influences to be mainly reflected on concrete strength In the later stage, concrete strength growth rate is larger after fly ash cement concrete 28d.

(2) influence of the cement type to concrete carbonization depth

It can see from Fig. 2-2, neat portland cement (S), ordinary portland cement (PS), slag cements in identical carbonization time (KS), in pulverized fuel ash cement (FS) concrete, the carbonation depth of fly ash cement concrete is maximum, and 7d carbonation depths reach 5.3mm, 14d carbonation depth reach 6.97mm；Neat portland cement concrete carbonization depth is minimum, and 7d carbonation depths reach 0.07mm, 14d carbonation depth reach 1.8mm；Ordinary portland cement, the concrete carbonization depth of slag cements are close, 7d carbonation depths point Not Wei 1.83mm, 1.73mm, 14d carbonation depths reach 4.2mm, 4.1mm.As carbonization time increases by four kinds of cement concrete carbonizations Depth increases, and concrete sample carbonation depth pace of change slows down after 14d, without significant changes.

(3) influence of the cement type to ion penetration resistance of concrete energy

Four kinds of different cement types can influence as Figure 2-3 ion penetration resistance of concrete.Different coagulating cements Native Anti-Chloride Ion Penetration is respectively slag cements>Ordinary portland cement>Pulverized fuel ash cement>Neat portland cement.28d curing ages Ordinary portland cement and Slag concrete have almost identical porosity, but slag admixture can adsorb Cl in slag cements^-Ion, Slag concrete has more preferable chloride-penetration resistance energy than ordinary portland cement concrete.28d fly ash cement concretes anti-chlorine from Sub- penetrating power is less than ordinary portland cement concrete the resistance of concrete to chloride ion penetration, main cause be it is flyash mixed in pulverized fuel ash cement and Though material can also adsorb Cl^-Ion, but ordinary portland cement concrete is smaller than fly ash cement concrete porosity, causes pulverized fuel ash cement Concrete the resistance of concrete to chloride ion penetration is less than ordinary portland cement concrete the resistance of concrete to chloride ion penetration.

(4) influence of the cement type to concrete antifreezing performance

Influence of the cement type to concrete antifreezing performance is as in Figure 2-4.From Fig. 2-in as it can be seen that Frozen-thawed cycled 300 times Afterwards, the relative dynamic elastic modulus of the concrete of different cement types are all higher than 80%, and the opposite of each cement type concrete is moved Property modulus difference it is smaller, it is seen that cement type on concrete antifreezing performance influence be not very notable.

2nd, cement fineness

(1) cement fineness is to working performance of concrete and Effect on Mechanical Properties

Cement fineness influences as shown in table 2-3 working performance of concrete, as Ball-milling Time increases, ordinary portland cement particle Fineness is gradually reduced, i.e., is gradually reduced than the increase of table 2- areas, concrete batching system mobility, the not levigate ordinary portland cement slump For 200mm, the ordinary portland cement slump of ball milling 1500s is 185mm.

As shown in Figure 2-5, as seen from the figure, different fineness cement mixes different cement fineness mechanical performance of concrete ongoing change Solidifying soil is gradually increased as curing time increases degree of hydration, and concrete crushing strength gradually increases, during identical maintenance 7d ages As cement granules fineness increase concrete crushing strength gradually increases, ball milling 1500s cement concrete strengths are not higher than levigate Cement concrete strength, concrete curing later stage increase more as curing time increases the thinner late strength of concrete of cement granules Slowly, influence of the cement granules fineness slightly to concrete strength is mainly reflected in the later stage.

Table 2-2 concrete mixs

Note：Wherein 14.958um is non-grinding fine cement (335m²/ kg), 13.145um is the cement (373m of ball milling 600s²/ Kg), 12.076um is the cement (402m of ball milling 1500s²/kg)。

(2) cement fineness influences concrete carbonization depth

Influence of the cement fineness to concrete carbonization depth is as shown in figures 2-6：As the different cement of carbonization time growth are thin Degree concrete carbonization depth all increases, and non-grinding fine cement concrete carbonization depth is maximum, and 7d carbonation depths reach 2.13mm, 14d Carbonation depth reaches 2.76mm, and 28d carbonation depths reach 4.26mm；The cement concrete 7d carbonation depths of ball milling 600s reach 1.54mm, 14d carbonation depth reach 2.17mm, and 28d carbonation depths reach 4.04mm, ball milling 1500s cement concrete 7d carbonation depths Reach 0.2mm, 14d carbonation depths reach 0.96mm, and 28d carbonation depths reach 2.5mm, with cement granules in identical carbonization time Fineness increase, concrete carbonization depth are constantly reduced.

(3) cement fineness influences Chloride Diffusion Coefficient in Concrete

Different fineness cement concrete Anti-Chloride Ion Penetration as illustrated in figs. 2-7, is mixed as cement granules fineness increases Solidifying soil chloride diffusion coefficient reduces degree unobvious, and Chloride Diffusion Coefficient in Concrete is maintained at 5 × 10^-12m²/ s, concrete When conserving 28d ages, as cement granules fineness increase concrete crushing strength gradually increases, maturing hole rate subtracts It is few, cause as cement fineness increase ion penetration resistance of concrete can be continuously increased.

(4) influence of the cement fineness to concrete antifreezing performance

Different fineness Cement Concrete Frost Resistance can be as illustrated in figs. 2 through 8.From Fig. 2-in it was found from, after 300 Frozen-thawed cycleds, Three kinds of different fineness (14.958um, 13.145um and 12.075um) cement concrete relative dynamic elastic modulus are respectively 86%, 91% and 86%.The trend for first increasing and reducing afterwards is presented with the increase of cement fineness for concrete relative dynamic elastic modulus, i.e., Concrete antifreezing performance reduces afterwards as the increase of cement fineness first increases.Therefore, in order to ensure the durability of concrete, cement Fineness will control within the specific limits.

2nd, influence of the mineral admixture to concrete performance

This item experimental study different cultivars of flyash (high calcium, low calcium) and different brackets (I grades, II grades) are to concrete The influence of working performance, mechanical property, carbonation properties, resisting chloride ion penetration performance and anti-freezing property.

1st, high calcium, Class F fly ash

(1) high calcium, Class F fly ash are to working performance of concrete and Effect on Mechanical Properties

See from table 2-3, Fig. 2-9, two kinds of admixture low calcium, high calcium flyash concrete initial flow degree all 190~ 200mm or so, low calcium, high-calcium fly ass influence working performance of concrete little.As curing age increases, admixture low calcium, The concrete crushing strength of high-calcium fly ass gradually increases, in identical curing age, high-calcium fly ash concrete mechanical property warp Shi Bianhua is more than Class F fly ash concrete, and high-calcium fly ash concrete later strength growth rate is than Class F fly ash concrete It hurry up.

Table 2-3 concrete mixs

(2) high calcium, Class F fly ash influence concrete carbonization depth

Mix low calcium, high-calcium fly ass concrete carbonization depth as shown in figs. 2-10, as carbonization time increases, mix low Calcium, high-calcium fly ash concrete carbonation depth all increase.High-calcium fly ash concrete carbonation depth is maximum, and 7d carbonation depths reach 2.2mm, 14d carbonation depth reach 2.76mm, and 28d carbonation depths reach 5.58mm, and Class F fly ash concrete seven d carbonation depths reach 1.542mm, 14d carbonation depth reach 2.06mm, and 28d carbonation depths reach 4.03mm.

(3) high calcium, Class F fly ash influence Chloride Diffusion Coefficient in Concrete

It can be seen that, the influence unobvious of low calcium, high-calcium fly ass to Chloride Diffusion Coefficient in Concrete are mixed from Fig. 2-11, Chloride Diffusion Coefficient in Concrete is maintained at 5 × 10^-12m²/ s, low calcium, high-calcium fly ass can adsorb Cl^-Ion reduces concrete Chloride diffusion coefficient, the concrete ratio of high-calcium fly ass is filled during 28d ages, and to mix Class F fly ash porosity small, causes to mix The Chloride Diffusion Coefficient in Concrete for increasing calcium fly ash is relatively small.

(4) influence of high calcium, Class F fly ash to concrete antifreezing performance

Mix low calcium, result such as Fig. 2-12 of high-calcium fly ash concrete relative dynamic elastic modulus after 300 Frozen-thawed cycleds It is shown：Admixture high-calcium fly ass is all higher than 80% than the value of the relative dynamic elastic modulus of Class F fly ash, and fills high calcium fine coal Grey concrete fills the frost resistance of high-calcium fly ash concrete better than low calcium ash, this is mainly height compared with the height of admixture low calcium ash The secondary hydration degree of calcium fly ash is more than low calcium ash, so that the concrete ratio for causing to fill high-calcium fly ass mixes Class F fly ash Porosity is small, thus its frost resistance is more excellent.

2nd, I grades, II grades of flyash

(1) quality of fly ash (I grades, II grades) is to working performance of concrete and Effect on Mechanical Properties

Keep gel material content, water-cement ratio, admixture dosage Stock allotment right, the constant feelings of the concrete mix slump Under condition, I grades, II grades of flyash to working performance of concrete and Effect on Mechanical Properties, as shown in table 2-4, Fig. 2-13.Fill I Level, the different quality flyash concrete initial flow degree of II grades of two kinds of flyash are all in 195mm or so, and quality of fly ash is to coagulation Native working performance influences not influence.Admixture I grades, II grades of flyash concrete mechanical property ongoing change as shown in Fig. 2-13, Gradually increase as curing age increase fills different quality flyash concrete compression strength, I grades of powder in identical curing age The mechanical property ongoing change of coal ash concrete is more than II grades of flyash concretes, but is not much different.

Table 2-4 concrete mixs

(2) quality of fly ash (I grades, II grades) influences concrete carbonization depth

I grades of admixture, the concrete carbonization depth of II two kinds of flyash of level are mixed as shown in Fig. 2-14 as carbonization time increases Add I grades, two kinds of flyash concrete carbonation depths of II levels all increase, in identical carbonization time, fill two kinds of I grades, II levels fine coal The carbonation depth of the concrete of ash has almost no change, and 7d carbonation depths are respectively 0.35mm, 0.4mm, and 14d carbonation depths are distinguished For 1.067mm, 1.167mm, 28d carbonation depths are respectively 4.6mm, 4.7mm.

(3) quality of fly ash (I grades, II grades) influences Chloride Diffusion Coefficient in Concrete

From Fig. 2-15, it can be seen that, I grades of admixture, influence of the two kinds of flyash of II levels to Chloride Diffusion Coefficient in Concrete are not Substantially, Chloride Diffusion Coefficient in Concrete is maintained at (3.5-4) × 10^-12m²Between/s, Powder ash adsorption Cl^-Ion reduces coagulation Native chloride diffusion coefficient, causes I grades of admixture, the Chloride Diffusion Coefficient in Concrete of II two kinds of flyash of level relatively small.

(4) influence of the quality of fly ash (I grades, II grades) to concrete antifreezing performance

Mix result such as Fig. 2-16 institutes of I grades, II grades flyash concrete relative dynamic elastic modulus after 300 Frozen-thawed cycleds Show：The value of I grades of flyash of admixture and II grades of flyash concrete relative dynamic elastic modulus is respectively 93.5% and 84.3%, very It is obvious to can be seen that the frost resistance for mixing I grades of flyash concretes is more than the concrete for mixing II grades of flyash.This is because I grades of fine coal Than II grades flyash of grey activity are big, and later-stage secondary degree of hydration is larger so that and concrete density increase, porosity reduce, from And cause the anti-freezing property increase of concrete.

3rd, influence of the additive to concrete performance

Additive not only has important influence to concrete to the working performance of concrete, but also to the durability of concrete Also there is extremely important influence.The different cultivars and different addition quantity of this item experimental study additive are to workability of concrete The influence of energy, mechanical property, carbonation properties, resisting chloride ion penetration performance and anti-freezing property.

1st, additive kind

(1) additive kind is to working performance of concrete and Effect on Mechanical Properties

It can see from table 2-5, high-efficiency water-reducing agent of poly-carboxylic acid volume minimum 1.4% (total pulvis is 0.28%) is high Dense naphthalene water reducer volume reaches 1.0%, and low dense naphthalene water reducer volume reaches 2.3%, could keep concrete initial flow Spend for 180-220mm.Polycarboxylic acids (PCA) water-reducing agent is best to concrete slump retentivity, there is concrete fluidity after 1h Concrete fluidity is in 150cm or so after 195cm or so, naphthalene system (highly concentrated, low dense) high efficiency water reducing agent 1h.Polycarboxylic acids (PCA) High efficiency water reducing agent has the characteristics that volume is low and water-reducing effect is good, and workability when going out machine of concrete is good, and no isolation, excreting water phenomenon go out It is existing.

Table 2-5 concrete mixs

As shown in Fig. 2-17, admixture variety classes high efficiency water reducing agent concrete different larval instar compression strength all increases, and mixes PCA High efficiency water reducing agent concrete crushing strength is 32.3MPa, 45.9MPa, 56.6MPa, mixes highly concentrated naphthalene water reducer concrete anti-compression Intensity is 27.7MPa, 43.70MPa, 52.2MPa, mix low dense naphthalene water reducer concrete crushing strength for 27.5MPa, 42.5MPa and 49.0MPa, admixture variety classes water-reducing agent concrete 3d intensity can reach 28d intensity 50%~90%, concrete Later strength also has growth trend.Different high efficiency water reducing agent early strength of concrete development speeds are polycarboxylate water-reducer>It is highly concentrated Naphthalene water reducer>Low dense naphthalene water reducer.

(2) additive kind influences concrete carbonizing performance

Different water-reducing agent concrete carbonization depths are filled as shown in Fig. 2-18, as carbonization time increases different efficient diminishings Agent concrete carbonization depth all increases.Low dense naphthalene water reducer concrete carbonization depth is maximum, and 7d carbonation depths reach 2.43mm, 14d carbonation depths reach 3.53mm, and 28d carbonation depths reach 5.07mm；Highly concentrated naphthalene water reducer concrete seven d carbonation depths reach 0.73mm, 14d carbonation depth reach 2.13mm, and 28d carbonation depths reach 4.33mm, mix polycarboxylate water-reducer concrete carbonization depth most Small, 7d carbonation depths reach 0.23mm, and 14d carbonation depths reach 1.8mm, and 28d carbonation depths reach 3.97mm.

(3) additive kind influences Chloride Diffusion Coefficient in Concrete

From Fig. 2-19 it can be seen that, mix low dense naphthalene water reducer concrete chloride ion diffusion coefficient be up to 2.67 × 10^-11m²/ s, mixes highly concentrated naphthalene water reducer concrete chloride ion diffusion coefficient for 6.58 × 10^-12m²/ s, mixes polycarboxylic acids diminishing Agent concrete chloride ion diffusion coefficient is 2.196 × 10^-12m²/s.When conserving 28d ages, admixture polycarboxylic acid concrete resists Compressive Strength ratio mixes naphthalene system (low dense, highly concentrated) water-reducing agent concrete crushing strength height, and concrete pore rate is small, chloride diffusion coefficient Smaller.

(4) influence of the additive kind to concrete antifreezing performance

The different Fresh Concrete with Admixtures of three kinds of admixture are after 300 Frozen-thawed cycleds, and each concrete relative dynamic elastic modulus are as schemed Shown in 2-20.From Fig. 2-in can be seen that, fill that the relative dynamic elastic modulus of polycarboxylic acid concrete are maximum, and incorporation naphthalene system is (low dense) mixed Solidifying soil relative dynamic elastic modulus are minimum, and between, that is, the frost resistance for mixing different Fresh Concrete with Admixtures is for naphthalene system (height)：Poly- carboxylic Acid>Naphthalene system (height)>Naphthalene system (low).

2nd, admixture dosage

(1) admixture dosage is to working performance of concrete and Effect on Mechanical Properties

From table 2-6, Fig. 2-21 as can be seen that as PCA high-efficiency water-reducing agent of poly-carboxylic acid volume increases, concrete slump has Proportional increased trend, during volume 1.0%PCA high-efficiency water-reducing agent of poly-carboxylic acid, concrete slump 100mm, with efficient The increase of water-reducing agent volume, when PCA high-efficiency water-reducing agent of poly-carboxylic acid volume is 1.2%, the concrete slump for mixing PCA increases from 100mm 190mm is added to, continues to increase PCA high-efficiency water-reducing agent of poly-carboxylic acid volumes, when volume is more than 1.4%, PCA high-efficiency water-reducing agent of poly-carboxylic acid For cement granules dispersiveness improve unobvious, main cause be volume to anion table 2- faces activity after 1.4% in cement Absorption on particle table 2- faces substantially completely, reaches saturation absorption point.Polycarboxylic acids (PCA) high efficiency water reducing agent has volume The characteristics of low and water-reducing effect is good, it is good to mix the concrete workability of PCA high-efficiency water-reducing agent of poly-carboxylic acid, does not isolate, not bleeding.

Table 2-6 concrete mixs

As shown in Fig. 2-22, admixture different addition quantity high efficiency water reducing agent concrete different larval instar compression strength all increases, and mixes 1.0%PCA high efficiency water reducing agents concrete crushing strength is 30,36.4,53.0MPa, mix 1.2%PCA high efficiency water reducing agent concrete Compression strength is 26.7,35.7,49.5MPa, mix 1.4%PCA high efficiency water reducing agents concrete crushing strength for 24.2,31.5, 45.3MPa, different addition quantity PCA high efficiency water reducing agent early strength of concrete have developed rapidly, and 3d intensity can reach 28d intensity 50%-90%, late strength of concrete also have growth trend.With the increase of PCA high efficiency water reducing agents volume, in identical curing age In concrete crushing strength have downward trend, its main cause be with PCA high efficiency water reducing agents volume increase, the efficient diminishings of PCA Deferred action increase of the agent to concrete, generates cement hydration process larger inhibitory action.

(2) admixture dosage influences concrete carbonizing performance

The concrete carbonization depth of the PCA high efficiency water reducing agents of different addition quantity is filled as shown in Fig. 2-23, with carbonization time Increase, the concrete carbonization depth of different addition quantity PCA high efficiency water reducing agents all increases.Mix 1.4%PCA high efficiency water reducing agent concrete carbon It is maximum to change depth, 7d carbonation depths reach 4.6mm, and 14d carbonation depths reach 9.4mm, and 28d carbonation depths reach 11.17mm；Mix 1.0% PCA high efficiency water reducing agents concrete carbonization depth is minimum, and 7d carbonation depths reach 1.32mm, and 14d carbonation depths reach 5.1mm, 28d carbon Change depth and reach 7.2mm, as PCA high efficiency water reducing agents volume increases, concrete carbonization depth gradually increases, main cause be with The increase of PCA high efficiency water reducing agents volume, concrete retarding effect increase, cement hydration process generate suppression, hardened concrete hole The increase of gap rate.

(3) admixture dosage influences Chloride Diffusion Coefficient in Concrete

It can see from Fig. 2-24, with the increase of PCA high efficiency water reducing agents volume, the chloride permeability diffusion coefficient of concrete Gradually increase, mixes 1.0%PCA high efficiency water reducing agent concrete chloride ion diffusions coefficient minimum, is 4.18 × 10^-12m²/ s, When PCA water-reducing agents volume is 1.4%, concrete chloride ion diffusion coefficient is 7.09 × 10^-12m²/s.Different addition quantity PCA high When imitating water-reducing agent concrete curing 28d ages, as PCA high efficiency water reducing agents volume reduces, the deferred action of concrete reduces, and mixes Solidifying soil pores rate is small, chloride permeability diffusion coefficient smaller.

(4) influence of the admixture dosage to concrete antifreezing performance

The concrete of different addition quantity additive is after 300 Frozen-thawed cycleds, and relative dynamic elastic modulus are as shown in Fig. 2-25.From Fig. 2-in can be seen that, when admixture dosage is respectively 1.0%, 1.1%, 1.2% and 1.4%, concrete is with respect to dynamic elasticity mould Amount is respectively 85%, 92%, 89% and 81%, i.e. concrete relative dynamic elastic modulus are in the increase of admixture dosage Now first increase the trend reduced afterwards.Therefore, in order to ensure concrete antifreezing performance, the volume of additive need to be controlled in appropriate model In enclosing, the increase of admixture dosage can increase the risk of concrete delamination isolation, the density of concrete be influenced, so as to reduce The anti-freezing property of concrete.

4th, influence of the coarse aggregate to concrete performance

(1) influence of the coarse aggregate grain size to concrete performance.It can see from table 2-7, the maximum particle diameter of coarse aggregate is bigger Concrete slump is generally also bigger, this is because its table 2- areas are relatively smaller when coarse aggregate grain size is larger, is wrapped in rough set Expect that the screed in table 2- faces is thicker, so as to be conducive to the mobility of concrete；From another angle analysis, the particle diameter to gather materials is got over Greatly, its reduction more corresponding than table 2- areas, required cement slurry volume are accordingly reduced, under certain workability and cement consumption, then Water consumption can be reduced and improve concrete strength.In this sense, the particle diameter to gather materials should try one's best select it is larger, but Not it is the bigger the better, under the probability of particle diameter existing defects more inside bulky grain is bigger, while particle is during the concrete mixing Heavy speed is faster, and pouring increases its inhomogeneities with being easy to produce isolation in transportational process, and molding difficulty of vibrating can increase, Influence the comprehensive performance of concrete, this point from table 2- it can be seen that, concrete crushing strength is anti-during maximum particle diameter increase And have a declining tendency；Meanwhile the increase of coarse aggregate maximum particle diameter also contributes to reduce the dosage of cement and water, reduces the heat of hydration And volume change, so as to improve concrete density and cracking danger can be reduced (for mass concrete).From table 2-4.1- 18 can see, and as coarse aggregate grain size increases, the drying contraction of concrete diminishes, this is because coarse aggregate is as concrete Skeleton, when particle diameter increase, are more advantageous to the overall anti-contracility of concrete.

Therefore coarse aggregate maximum particle diameter select depending on actual conditions, when works volume is larger (such as cushion cap), And reinforcing bar it is not close when, 31.5-40mm may be selected in coarse aggregate maximum particle diameter, and when structural concrete strength is higher, mixed to be lifted The comprehensive performance of soil is coagulated, 25mm may be selected in coarse aggregate maximum particle diameter.

Influence of the table 2-7 coarse aggregate grain sizes to concrete performance

(2) table 2-8 is affecting laws of the coarse aggregate elongated particles to workability of concrete, mechanical property.

Influence of the table 2-8 coarse aggregates elongated particles to concrete performance

With the raising of elongated particles, working performance of concrete is deteriorated, and compression strength is on a declining curve, and concrete passes through Relative resilient modulus also decreases (but unobvious, influence degree are smaller) after crossing 100 Frozen-thawed cycleds.Elongated particles reach During to 19%, all substantially reduced when the fresh concrete slump, water-retaining property and cohesiveness are compared with 5%, and isolation bleeding occur Phenomenon；When elongated particles are 5-14%, concrete crushing strength change is little, when elongated particles reach 19%, pressure resistance Degree have dropped 10% or so.

Working performance influence of the coarse aggregate elongated particles on concrete is very big, this is because coarse aggregate is round, particle shape is got over Rule, frictional resistance is smaller, and the slump and divergence of concrete are also bigger, easy to pump and construct.

Elongated particles are higher, and concrete strength is lower, this is because during concrete vibrating, moisture is easy to from strip With flat it is thick gather materials nearby secrete, interface area Behavior of Hardened Cement Paste defect is more, and easily forms crack.The coarse aggregate of gill shape is got over Height, the position of easily aggregation moisture film is more in concrete, and original fracture is also more, in addition the intensity of gill shape coarse aggregate itself also compared with It is low, therefore flat-elongated particles content is higher, concrete crushing strength is lower.

And from the point of view of anti-freezing property, each group concrete relative dynamic elastic modulus difference after 100 Frozen-thawed cycleds, But relatively from the point of view of difference it is little, it can be seen that influence of the coarse aggregate elongated particles to concrete antifreezing performance is smaller.It is and thick Gathering materials, middle flat-elongated particles content is more, and concrete early-age shrinkage is bigger.This is because relative to multi-angular, subsphaeroidal coarse aggregate For, the intensity of gill shape coarse aggregate is relatively low, and the rejection ability shunk to Behavior of Hardened Cement Paste is also lower.

(3) mechanical property of the level pairing concrete of coarse aggregate has and obviously influences, and good the gathering materials of grading has Larger bulk density and less voidage.In the case where other conditions are identical, the small collection of large bulk density, voidage Material, institute's concrete batching can obtain higher intensity and compactness.According to maximum density curve theory, solid particle presses granularity Size, well-regulated assembled arrangement, thickness collocation, can obtain density maximum, the mixture of gap minimum.Therefore.Stone Bulk density is gathered materials ratio there are a suitable thickness, and the bulk density and most of maximum can be obtained in gathering materials for this ratio Small voidage, obtains highest concrete strength.

(4) rubble, cobble and crushing gravel have obvious difference for the performance of concrete.Level is used in this experiment Match somebody with somebody, rubble, cobble and the crushed-gravel similar in index such as clay content, elongated particles are studied accordingly, be specifically shown in Table 2-9.

Influence of the table 2-9 coarse aggregates kind to concrete performance

Note：Crushed-gravel (55%) represents 2- crushing gravels and reaches the ratio of 2 and the above plane of disruption as 55%.

It can see from table 2-9, with respect to rubble, the working performance of boulder concrete is more preferable, and the slump significantly improves, still Its intensity is relatively low, and 28d compression strength reduces about 12%.And cobble is after broken, the mechanical property of institute's mixing concrete obtains Improvement is arrived, when wherein the plane of disruption reaches 85%, 28d compression strength, flexural strength improve more 10%.And from endurance quality From the point of view of, the relative resilient modulus difference after 100 freeze thawing is also smaller with crushed stone concrete for crushing gravel.Therefore, it is as long as broken Face reaches certain ratio, and crushed-gravel concrete and ordinary gravel concrete difference are smaller, are fully able to meet the requirements.

(5) test, mainly have to draw a conclusion more than：

1. the maximum particle diameter of coarse aggregate is bigger, concrete slump is bigger, but the selection of its particle diameter needs to combine actual feelings Depending on condition, when works volume is larger (such as cushion cap), the optional 31.5-40mm of coarse aggregate maximum particle diameter, and when structural concrete is strong When degree is higher, to lift the comprehensive performance of concrete, coarse aggregate maximum particle diameter can use 25mm even 20mm；

2. coarse aggregate elongated particles are directly related to the workability and mechanical property of concrete, advised with reference to respective standard Model, concrete elongated particles should be controlled within 15%, and high performance concrete elongated particles should try one's best control 10% Within；

3. when resource is limited, it may be considered that crushing gravel substitution rubble is applied in Medium and low intensity grade concrete, but It is to need strictly to control its plane of disruption and particle shape, to ensure the performance of concrete.

5th, influence of the fine aggregate to concrete performance

Fig. 2-26 to 29 be sand modulus of fineness and clay content to the affecting laws of concrete performance, wherein fineness mould Number takes 2.5,2.7,2.9,3.2, and sand clay content takes 1.5%, 2.3%, 2.8% and 3.5%.

Analyzed from workability, all in all with the raising of sand fineness modulus, concrete slump is bigger, this is because Sand is thinner, and its table 2- areas are bigger, and in the case where cement mortar dosage is certain, the slurry for being wrapped in sand table 2- faces is thinner mixed Solidifying soil is streaky dry thick, and the slump is also smaller.And from the point of view of mechanical property, influence of the sand fineness modulus to C30 concrete It is smaller, and then have obvious influence on the intensity of C50 concrete, sand is thinner, and the compression strength of concrete is smaller, when fineness mould Number from 2.9 be reduced to 2.5 when, concrete 28d compression strength reduces 3.8MPa.

Therefore, the bigger concrete strength of sand fineness modulus is often higher, and the slump is also bigger, but modulus of fineness is unsuitable It is excessive.From the point of view of this experiment, when modulus of fineness is from 2.9 to 3.2 when preparing C50 concrete, its slump, mechanical property are without bright Aobvious change (modulus of fineness is excessive, and sand voidage can increase, and the slurry amount that filling gap needs also can substantially increase), and coagulation Native cohesiveness and water-retaining property are often deteriorated, therefore in highlands concrete batching, consider concrete workability, Mechanical property and endurance quality, sand fineness modulus are advisable with controlling 3.0 or so.

Table 2-10 clay contents influence C50 endurance performance of concrete

Fig. 2-30 to 33 is influence of the sand clay content to concrete performance, its affecting laws is with stone clay content to coagulation The influence of soil nature energy is more similar.When sand clay content be 1.5% when concrete slump compared with clay content 3.5% when improve 20% or so.This is because high-efficiency water-reducing agent of poly-carboxylic acid, belongs to table 2- faces activating agent, activity is very strong, and the soil tool in aggregate There is interlayer structure, can largely adsorb polycarboxylate dehydragent molecule, so that water-reducing agent loses activity, and poly- shuttle acid water-reducing agent Volume again very little, so seeming particularly sensitive to the cement content in aggregate.There is research table 2- bright, use the higher collection of clay content During material, to reach identical fluidity, the volume of polycarboxylate water-reducer is than using the low raising 30~50% of gathering materials of clay content.

And sand clay content is higher, the intensity of concrete is also lower, from Fig. 2-in it can be seen that, for C50 concrete, contain Compression strength is only 53.6MPa when mud amount reaches 3.5%, with respect to clay content be 1.5% when reduce 12% or so.This is Because the mud pellet footpath very little in natural sand, the table 2- faces that gather materials easily are wrapped in, hinder the bonding gathered materials between Behavior of Hardened Cement Paste, are formed soft Weak boundary layer, becomes the weak area in concrete, and when being subject to external force to destroy, the weak area of concrete is easily destroyed, causes The strength character of concrete reduces.

In addition, it can be seen that, with the raising of clay content, concrete durability is gradually deteriorated, clay content from table 2-10 For 1.5% when, concrete Relative dynamic modulus of elasticity still has 68.5% after 300 Frozen-thawed cycleds, it is seen that its frost resistance can reach The standard of F300, and when clay content reaches 3.5%, concrete Relative dynamic modulus of elasticity is only 47.5% after 300 Frozen-thawed cycleds, Anti-freezing property is decreased obviously.And from the point of view of 60d dryings are shunk, add 37% or so when clay content 3.5% is with respect to 1.5%.This Higher mainly due to clay content, the structure of concrete gets over leakiness, and the caking property of inside concrete is poorer, therefore durability It is poorer.

(3) test, mainly have to draw a conclusion more than：

The clay content of sandstone will directly influence workability, mechanical property or even the endurance quality of concrete, when sand contains Mud amount reaches 3.5%, and workability, mechanical property and the endurance quality of concrete all decline substantially, from matching somebody with somebody for high performance concrete Controlling angle, sand clay content are preferably controlled within 2%, to ensure the endurance quality of concrete；

Influence of the modulus of fineness of sand to the workability of concrete, mechanical property is relatively large.Sand is thicker, concrete The slump is bigger, and intensity is also higher.Therefore highlands high performance concrete sand fineness modulus is preferably controlled 3.0 or so, no It is preferably excessive or too small.The modulus of fineness scope of sand used in normal concrete can suitably relax, general it is contemplated that taking 2.5- 3.0。

6th, concrete mix optimization design research under low temperature difference environment

This subitem combines multigroup match ratio under Qinghai Area actual conditions design tri- strength grades of C30, C40, C50, main Study water-cement ratio (0.31-0.48), cementitious material (350-530kg/m³), doping quantity of fly ash (0-30%), sand coarse aggregate ratio (36- Etc. 42%) influence of the key index to concrete performance, specific match ratio are shown in Table shown in 2-11.It is main to investigate workability of concrete Energy, mechanical property, cracking resistance and anti-freezing property.

Concrete mix optimization design match ratio under table 2-11 low temperature, big temperature difference environment

(1) influence of the water-cement ratio to concrete performance

In the case of not fly ash, 0.48,0.45,0.40,0.37 and 0.34 5 kind of water-cement ratio pair have mainly been investigated The influence of concrete performance.

1st, influence of the water-cement ratio to working performance

The slump of different water-binder ratios concrete is as shown in Fig. 2-34.It can be seen that by Fig. 2-34, each group concrete slump It is all higher than more than 170mm, it is seen that the working performance of different strength concrete is satisfied by construction requirement.In addition, from Fig. 2-34 In it is also seen that concrete slump increased with the increase of water-cement ratio, this is mainly the increasing of Free water in concrete Add and concrete flowability is increased.

2nd, influence of the water-cement ratio to mechanical property

Influence of the water-cement ratio to mechanical performance of concrete is as shown in Fig. 2-35, as can be seen from Figure, the condition of identical water-cement ratio Under, concrete crushing strength increases with the increase of curing age, and presentation growth rate early period is fast, and the later stage gathers way Slow rule.When water-cement ratio is respectively 0.48,0.45,0.40,0.37 and 0.34,7d pressure resistances are respectively 28d compression strength 70.7%, 72.0%, 74.6%, 76.9% and 72.5%, 28d compression strength be respectively 59.9MPa, 54.2MPa, 47.6MPa, 40MPa and 34.8MPa, can meet concrete design strength.

In addition, by Fig. 2-it is also seen that under the conditions of identical age, concrete crushing strength, flexural strength and move Property modulus reduced with the increase of water-cement ratio, this mainly due to water-cement ratio increase can increase hardening after concrete hole Rate, so that concrete density is reduced, so that the rule declined is presented in concrete strength.Wherein C30 concrete water-cement ratios with 0.45 or so is advisable, and C40 concrete is advisable with 0.40 or so, and C50 is then advisable with 0.34 or so.

3rd, influence of the water-cement ratio to cracking resistance

Influence of the water-cement ratio to crack-resistant performance of concrete is as shown in Fig. 2-38.It can be seen that from figure, crack index and cracking face Both evaluation indexes of product have good correlation, and crack index and area of cracks increase with the increase of the ratio of mud, i.e., The trend of reduction is presented with the increase of water-cement ratio for the crack resistance of concrete.In addition, by Fig. 2-it is also seen that with the ratio of mud Reduction, crack index and area of cracks evaluation index reduce amplitude and reduce.

4th, influence of the water-cement ratio to anti-freezing property

Using the concrete of different water-binder ratios after 300 Frozen-thawed cycleds, each relative dynamic elastic modulus are as shown in Fig. 2-39. As seen from the figure, when water-cement ratio is respectively 0.48,0.45,0.40,0.37 and 0.34, concrete is opposite after 300 Frozen-thawed cycleds Dynamic modulus of elasticity is respectively 65%, 72.1%, 77%, 83.5% and 88.3%, i.e., with the increase of water-cement ratio, concrete warp Relative dynamic elastic modulus, which are presented, after 300 Frozen-thawed cycleds significantly reduces trend, this is because the increase of water-cement ratio reduces concrete Density, so as to there is more Free waters to enter inside concrete, so that under Frozen-thawed cycled, with the crystallographic expansion of Free water, So that concrete is deteriorated in swelling stress effect repeatedly.Therefore, in Qinghai Province area low temp area, often contacted with water Structure need to use the concrete of low water binder ratio.

(2) influence of the gel material content to concrete performance

Using flyash as admixture, flyash equivalent substitutes 20% cement, controls water-cement ratio to immobilize for 0.34, By gel material content from 350kg/m³~500kg/m³Change is to working performance of concrete, mechanical property, cracking resistance and resists Freeze the influence of performance.

1st, gel material content is to working performance of concrete and Effect on Mechanical Properties

Research match ratio and working performance of concrete of the gel material content to concrete performance are as shown in table 2-13.By scheming Understand, using flyash as admixture, flyash substitution cement is 20%, as gel material content reduces admixture dosage Gradually decrease, concrete batching system initial flow degree is maintained at 200-220mm, but concrete work state is deteriorated.

Flyash is influenced as shown in Fig. 2-40,41 mechanical performance of concrete as admixture, gel material content, with Curing age increase, degree of hydration are gradually increased, and different gel material content concrete crushing strengths gradually increase, identical maintenance As the total dosage increase concrete crushing strength of folk prescription concrete gel material is reduced in age.And the situation that water-cement ratio is constant Under, with the raising of gel material content, the change of concrete dynamic modulus of elasticity is not much different.It can be seen from the above that the mechanics of concrete Performance is often depending on water-cement ratio, and on the premise of water-cement ratio is constant, it is little with the relation of gel material content.

Table 2-13 concrete mixs

2nd, gel material content influences crack-resistant performance of concrete

Gel material content influences as shown in Fig. 2-42 crack-resistant performance of concrete.As seen from the figure, from crack index and opening Broken face accumulates two evaluation indexes can, hence it is evident that finds out, when cementitious material is 460kg/m³When, crack-resistant performance of concrete is optimal, When this is mainly due to gel material content increase, free water amount is reduced in one side concrete, this is to crack-resistant performance of concrete It is positive-effect；On the other hand, cementitious material increase concrete material chemical shrinkage, this is negative effect to crack-resistant performance of concrete, Optimal gel material content is occurred as soon as under two aspects are comprehensive.Therefore, it is preferably controlled in for C50 concrete gel material dosages 500kg/m³Within, the risk of concrete bracing can be reduced.

3rd, gel material content influences concrete antifreezing performance

Gel material content influences as shown in Fig. 2-43 concrete antifreezing performance.From figure it will be evident that with gelling The reduction of material utilization amount, concrete relative dynamic elastic modulus after 300 Frozen-thawed cycleds reduce, when gel material content is respectively 500kg/m³、460kg/m³、 400kg/m³And 350kg/m³When, relative dynamic elastic modulus are respectively 95%, 92%, 86% and 82%, i.e., with the increase of gel material content, concrete frost resistance increase.This is mainly to form aquation after cementitious material aquation Result of the product to Concrete Filled densification.

The research of influence of the comprehensive gel material content to concrete performance, it is mixed in design from the point of view of gel material content Carried out during solidifying soil match ratio in strict accordance with the design method of high performance concrete, it is stringent to control water-cement ratio and cementitious material to use Amount, C30 strength grades concrete gel material are controlled in 380kg/m³Within, the control of C40 strength grades concrete gel material In 420kg/m³Within, and C50 concrete gel materials dosage is then no more than 500kg/m³.With the raising of gel material content, Concrete strength is continuously improved.

(3) influence of the doping quantity of fly ash to concrete performance

To three kinds of different strength concretes, it have studied substitute 0%, 15% and 30% cement with flyash equivalent respectively Concrete performance affecting laws.

1st, influence of the doping quantity of fly ash to working performance of concrete and mechanical property

Each group working performance of concrete is as shown in table 2-14.From the point of view of C30~C50 working performance of concrete, with fine coal The raising of grey volume, the reduction that concrete sand ratio all can be appropriate, volume, which reaches 30%, which less mixes group sand coarse aggregate ratio, can reduce by 2~4 hundred Branch, and do not influence its working performance completely.When doping quantity of fly ash is 15%, due to the particle shape effect of flyash, mix Solidifying geotechnique makees functional, and water-retaining property and cohesiveness can be significantly improved；After doping quantity of fly ash reaches 30%, mix The solidifying soil slump has still been lifted, but when its water-retaining property and adhesive aggregation performance compared with doping quantity of fly ash are 15% has but dropped It is low, or even there is micro excreting water phenomenon.It can be seen from the above that doping quantity of fly ash is not the higher the better, in general flyash has One the optimum mix amount, from the point of view of this item experiment, the volume of flyash should try one's best control within 30%, generally from the point of view of it is left with 15% The right side is advisable.

Working performance of concrete under table 2-14 low temperature, big temperature difference environment

Each group working performance of concrete is as shown in table 2-15 and table 2-16.Wherein table 2-15 is coagulation under the conditions of standard curing Each age compression strength of soil, table 2-17 is to be directed to engineering site actual environment, and each age under C50 concrete cured under same condition is resisted Compressive Strength testing research.

The concrete crushing strength rule of development-standard curing under table 2-15 low temperature, big temperature difference environment

The concrete crushing strength rule of development-cured under same condition under table 2-16 low temperature, big temperature difference environment

Note：1. data represent the percentage that 2- concrete seven d compression strength accounts for 28d compression strength in bracket；

2. first 7 days use field curing using covering+watering maintenance, later stage.

From table 2-16 as it can be seen that under standard curing environment, when not fly ash, concrete seven d intensity can reach 28d The 75% of intensity, when doping quantity of fly ash reaches 30%, 7d intensity is only capable of reach 28d 65%.Compared to benchmark not fly ash From the point of view of group, 7d compression strength is reduced within 10% when doping quantity of fly ash is 15%, and compression strength reduces when volume is 30% Nearly 20%.And from the point of view of 28d intensity, during doping quantity of fly ash 15%, concrete strength reduces by 5% or so, and intensity drops during volume 30% Low 5-10%.Influence of the flyash for early strength of concrete as can be seen here is larger later strength to be influenced opposite It is smaller, the development speed of its later strength will apparently higher than not fly ash group, especially volume when within 15% concrete All it is fully able to reach design requirement.From Fig. 2-45 and Fig. 2-46 can also, it is evident that the incorporation of flyash to agent on crack resistance of concrete Folding intensity and dynamic modulus of elasticity have a significant impact, and volume is bigger, and influence is also bigger, and it is then smaller more to arrive consequent effects.

As it can be seen that concrete 28d intensity is compared with standard curing condition under cured under same condition from table 2-17 and Fig. 2-46 Decrease.Due to being within first 7 days covering+water seasoning, the basic guarantee humiture of concrete, therefore its strength development compared with It hurry up, the intensity that lower concrete is supported with marking is suitable.And the later stage due to slow for outdoor cured under same condition, its strength development, and compare Mark supports and then reduced by only 5%-10% or so.Early curing is for the importance of concrete, especially preceding 7d, health as can be seen here The reinforcement of measure can strengthen the development of concrete intensity early period, so as to ensure the later strength of concrete.Especially for height Original area, dry, temperature is low, strength development is slow, therefore early stage health seems increasingly important, ensures concrete water early period The humiture that changing needs can greatly promote the development of its early strength, so as to advantageously ensure that final strong of concrete structure Degree.

2nd, influence of the doping quantity of fly ash to crack-resistant performance of concrete

Influence of the doping quantity of fly ash to crack-resistant performance of concrete is studied, this experiment selection water-cement ratio is 0.33, flyash mixed Amount is respectively 0%, 10%, 15% and 30%.Specifically coordinate such as shown in table 2-4.2-11, wherein 33KB, 33F10,33F15 With 33F20 respectively table 2- show doping quantity of fly ash be respectively 0%, 10%, 15% and 30%, 33F10S10 table 2- show flyash and Ground slag respectively substitution 10%, is mixed again.

Influence of the different doping quantity of fly ash to crack-resistant performance of concrete is as shown in Fig. 2-47.Flyash and ground slag incorporation Afterwards, the cracking resistance of concrete can be greatly improved, but as doping quantity of fly ash further increases, increases to 20% from 15% When, the lifting effect unobvious to crack-resistant performance of concrete.

Influence match ratio of the table 2-17 flyash to crack-resistant performance of concrete

3rd, influence of the doping quantity of fly ash to concrete antifreezing performance

Experiment is carried out to tetra- groups of concrete antifreezing performances of 33KB, 33F10,33F15 and 33F20 in table 2-17 match ratios to grind Study carefully, its result is as shown in Fig. 2-48.From figure as it can be seen that concrete is after 300 Frozen-thawed cycleds, relative dynamic elastic modulus are with fine coal The trend for first increasing and reducing afterwards is presented in the increase of grey volume, and wherein doping quantity of fly ash is optimal for 15%.It is this is because flyash mixed When amount is less than 15%, the increase of doping quantity of fly ash is under the action of secondary hydration so that concrete density increase；Work as flyash When volume is more than 15%, since cement consumption is reduced in cementitious material, concrete early hydration product reduces so that concrete hole Gap rate increase, so as to reduce the frost resistance of concrete.

Therefore, in low, the dry highlands of temperature, it is contemplated that early strength of concrete effective development, in conjunction with Consider affecting laws of the flyash to concrete anticracking and anti-freezing property, it is proposed that doping quantity of fly ash is in C50 grade concretes 15% or so.

(4) influence of the sand coarse aggregate ratio to concrete performance

For C50 strength grade concrete, fixed water-cement ratio is 0.35, is considered as 33%, 36%, 39% and 42% and grinds Study carefully influence of the sand coarse aggregate ratio to concrete performance.Specifically coordinate such as shown in table 2-18.

Table 2-18 concrete mixs

1st, influence of the sand coarse aggregate ratio to working performance of concrete and mechanical property

Sand coarse aggregate ratio is shown in Table working performance of concrete shown in 2-19, influence of the sand coarse aggregate ratio to mechanical performance of concrete such as Fig. 2-51 institutes Show.By table 2-19 as it can be seen that being reduced with the sand coarse aggregate ratio increase concrete mix slump, concrete batching system workability improves.With Curing age increase, different sand coarse aggregate ratio dosage concrete crushing strengths increase, as sand coarse aggregate ratio increases concrete in identical curing age Compression strength, flexural strength, dynamic modulus of elasticity first increases and then decreases variation tendency, there are an optical sand percentage value.

2nd, influence of the sand coarse aggregate ratio to crack-resistant performance of concrete

Influence of the sand coarse aggregate ratio to crack-resistant performance of concrete is as shown in Fig. 2-52.As seen from the figure, crack index and area of cracks two A cracking resistance evaluation index increases trend afterwards as sand coarse aggregate ratio increase presents first to reduce, and wherein sand coarse aggregate ratio is optimal for 0.39.There are one Optical sand percentage makes crack-resistant performance of concrete optimal.

3rd, influence of the sand coarse aggregate ratio to concrete antifreezing performance

Influence of the sand coarse aggregate ratio to concrete antifreezing performance is as shown in Fig. 2-53.By figure it will be evident that concrete is moved relatively Property modulus occur first increase the trend that reduces afterwards with sand coarse aggregate ratio increase, when sand coarse aggregate ratio for 0.39 when, concrete is through 300 Frozen-thawed cycleds Relative dynamic elastic modulus are maximum afterwards, i.e., anti-freezing property is optimal.

Experiment of the comprehensive sand coarse aggregate ratio to the affecting laws of working performance of concrete, mechanical property, cracking resistance and anti-freezing property Research and analyse, sand coarse aggregate ratio it is too small or it is excessive have detrimental effect to concrete performance, there are optical sand percentage.Therefore, in concrete During mix-design, optical sand percentage can be selected.For C50 concrete sand ratios under low temperature difference environment, it is proposed that selection 0.39 or so, if using coarse sand in engineering, sand coarse aggregate ratio can get 0.41, and according to fine sand, then sand coarse aggregate ratio is no more than 0.40.

(5) influence of the altitude environment to concrete performance

Highlands temperature is low, and the temperature difference is big, and Frozen-thawed cycled is serious, it is therefore necessary to which the frost resistance of concrete is ground Study carefully.And plateau air pressure is smaller, therefore may produce compared to its stability to bubble in concrete under normal barometric pressure certain Influence.

This subitem uses the concrete of C50 strength grades, coordinates such as table 2-19.

Table 2-19 concrete mixs

Note：Wherein additive 1 is polycarboxylate water-reducer, and additive 2 is air entraining agent.

By being shown in Table 2-20 to working performance of concrete test result.

The working performance and anti-freezing property of concrete under table 2-20 difference conditions of molding

Note：The condition of molding on plateau is about 3500 meters of height above sea level.

From table 2-20 and 15, it can be seen that, after being mixed with 0.03% air entraining agent in concrete, the air content of concrete is all Obvious increase has been obtained, and concrete relative dynamic elastic modulus are also apparent raising after 300 Frozen-thawed cycleds, agent on crack resistance of concrete Freeze performance to be obviously improved.

No matter air entraining agent is mixed, molding concrete 's air-containing is relatively small under high conditions, by taking C50 as an example, its In for not mixing air entraining agent group C50-1, concrete 's air-containing reduces 22.2% compared to Plain under altitude environment, and mixes air entraining agent Group C50-2, the air content of concrete reduces 27.1% compared to Plain under altitude environment.And the reduction of air content is also brought at the same time The reduction of concrete antifreezing performance.This, as a kind of table 2- faces activating agent, is by reducing liquid mainly due to air entraining agent Table 2- faces tension force be easily formed bubble, and table 2- faces tension force is liquid table 2- surface layers is produced since molecular attraction is unbalanced The raw tension force acted on along table 2- faces in any boundary line, is typically due to environment difference, the molecule in interface is with being in phase sheet When internal molecule institute stress is that different air pressures reduce, the gas molecule spacing increase in air, attraction weakens, and liquid Volume density is influenced very little by air pressure, and the molecule being now on liquid-gas interface is subject to the pulling force of fluid molecule obviously Higher than normal pressure situation, i.e., the table 2- faces tension value of liquid is bigger than normal under low pressure, thus equivalent to the bleed energy for weakening air entraining agent Power, so as to cause bleed effect to decline, concrete 's air-containing reduces.

(6) influence of the raw material to concrete shrinkage and creep

(1) testing program

Investigation strength grade of concrete is C50, by varying the Stock allotment right of concrete, investigates the ratio of mud, flyash Affecting laws of the factors such as volume, sand coarse aggregate ratio to concrete shrinkage and creep.Experiment coordinates such as shown in table 2-21.This item is by scene Raw material return Nanjing and carry out experimental study.Specific research index is 28d self-constrictions, 60d dries contraction, 180d creep degrees and Xu Variable coefficient.

Concrete shrinkage and creep match ratio under table 2-21 low temperature difference environment

(2) influence of the water-cement ratio to concrete shrinkage and creep

Influence of the water-cement ratio to self-constriction：Influence of the water-cement ratio to self-constriction is as shown in Fig. 2-54.As seen from the figure, water-cement ratio Be reduced to 0.35,0.33,0.31 and 0.29 respectively from 0.37, concrete self-shrinkage increases respectively to 122 from 104,165,196, 204, i.e. concrete self-shrinkage value increases with the reduction of water-cement ratio.Water-cement ratio decides mortar architecture solid phase and liquid phase Relative volume content.With the aquation of glue material, solid volume increase, liquid phase volume reduces, and reduces the gap of water mudrock structure And become closely knit.The smaller gap for needing solid phase to fill of water-cement ratio is also smaller, then thin for the concrete of big water-cement ratio Kong Duo, gross porosity are few, while the degree of refinement in gap is also higher, and concrete critical radius is just smaller, and the self-constriction of generation is just bigger.

Water-cement ratio is to the dry influence shunk：Influence of the water-cement ratio to concrete drying shrinkage is as shown in Fig. 2-55.By scheming Understand, when water-cement ratio is reduced to 0.35,0.33,0.31 and 0.29 respectively from 0.37, coagulation drying is shunk to be reduced to respectively from 282 265th, 244,241,236, i.e. concrete drying shrinkage reduces with the reduction of water-cement ratio.This is because：It is dry to shrink mainly It is to shrink caused by pore detail dehydration, the increase of water-cement ratio not only increases the porosity of material, and increases the company in hole The general character, the migration in portion from the inside of such pore water or evaporation rate will increase, so as to cause cement-based material to be dried Shrink increase.

Influence of the water-cement ratio to creeping：Influence of the water-cement ratio to concrete creep is as shown in Fig. 2-56.According to national regulation 《Standard for test methods of longterm performance and durability of ordinary concrete》(GBJ 82-8) tests the creep degree of concrete, concrete glue Than being respectively 0.4,0.35,0.31.As seen from the figure, water-binder ratio is bigger, and creep degree is bigger, when the ratio of mud is 0.35 320d creep degrees are 48.94 × 10^-6/ MPa, 320d creep degrees reach 69.01 × 10 when the ratio of mud is 0.4^-6/ MPa, adds 41.0%.

Table 2-22 different water-binder ratios concrete 180d Creep Coefficients

Water-cement ratio	180d Creep Coefficients
		0.4	5.36
0.35	3.23
		0.31	3.03

(3) influence of the doping quantity of fly ash to concrete shrinkage and creep

Influence of the flyash to self-constriction：Influence of the flyash to self-constriction is as shown in Fig. 2-57.As seen from the figure, each group is tried Part Early self-shrinkage value increases sharply, and with the growth of age, each group self-shrinking value gradually tends towards stability；The incorporation of flyash, Reduce the self-constriction of concrete；During doping quantity of fly ash 10%, 15% and 20%, self-constriction reduces reduce 13.3% respectively, 21.4% and 31.0%, double-doped flyash and slag powders it is each 10% when, self-desiccation shrinkage value reduces 27.1%.

Since flyash activity is relatively low, reaction takes a long time completely, therefore when with coal ash instead cement, will subtract Few aquation phase amount, increase constraint phase amount, and the fly ash grain elasticity modulus of glass phase is higher, and these are all received to reducing Contracting is favourable.When substitution rate is relatively low, the diluting effect of flyash makes the actual ratio of mud increase of cement, and Among Cement Hydration Degree improves, real It will not have much impact to the quantity of aquation phase on border, i.e., contraction will not be largely reduced because of the incorporation of flyash.

Flyash is to the dry influence shunk：Flyash is to the dry influence shunk as shown in Fig. 2-58.As seen from the figure, powder The incorporation of coal ash, reduces the dry contraction of concrete, and drying shrinkage reduces with the increase of doping quantity of fly ash, doping quantity of fly ash 10%th, 15% and 20% when, dry shrink reduces by 10%, 17% and 21% respectively.Double-doped flyash and slag powders it is each 10% when, Shrinkage value reduces 20%.

Influence of the flyash to creeping：Flyash is to the influence crept as shown in Fig. 2-59.Fig. 2-59 is water-cement ratio 0.35, The creep degree changing rule of concrete when doping quantity of fly ash is 0%, 15%, 30%, as seen from the figure, when doping quantity of fly ash is 15% When, significantly reduced compared to creep degree when not mixing, but when volume reaches 30%, Xu when concrete creep degree is with respect to volume 15% Variation then changes less.The reason is that the elasticity modulus of fly ash grain is with respect to cement granules bigger, during its volume 15%, its micro- collection Material effect can be played preferably, so as to suppress creeping for concrete.And when doping quantity of fly ash reaches 30%, it is to concrete The inhibitory action crept then unobvious, this is probably since the compactness of concrete inner structure is tended not to flyash The raising of volume and improve, wherein there is the optimal value of a volume, will not be lifted more than concrete density after this value Even decline.Some researches show that when doping quantity of fly ash reaches 60%, creeping for concrete greatly improves on the contrary, this and powder The situation that coal ash is combined with basal body interface has direct relation.

Table 2-23 difference doping quantity of fly ash concrete 180d Creep Coefficients

FA%	180d Creep Coefficients
		0	3.61
15	3.73
		30	4.58

(4) influence of the sand coarse aggregate ratio to concrete shrinkage and creep

For C50 strength grade concrete, fixed water-cement ratio is 0.35, is considered as 33%, 36%, 39% and 42% and grinds Study carefully influence of the sand coarse aggregate ratio to concrete performance.Specifically coordinate such as shown in table 2-24.

Table 2-24 concrete mixs

Influence of the sand coarse aggregate ratio to self-constriction：Influence of the sand coarse aggregate ratio to concrete self-shrinkage is as shown in Fig. 2-60.Can from Fig. 2-60 Find out, when sand coarse aggregate ratio increases to 36%, 39% and 42% from 33%, concrete 180d self-shrinking values increase to 238 from 217, 265th, 284, i.e. concrete self-shrinkage increases with the increase of sand coarse aggregate ratio, this causes the body of coarse aggregate mainly due to sand coarse aggregate ratio increase Fraction reduces, so as to weaken to the inhibition of concrete shrinkage, final table 2- is now self-constriction increase.

Sand coarse aggregate ratio is to the dry influence shunk：Influence of the sand coarse aggregate ratio to concrete drying shrinkage is as shown in Fig. 2-61.Can from figure Go out, when sand coarse aggregate ratio increases to 36%, 39% and 42% from 33%, concrete 180d drying shrinkage values increase to 284 from 261, 305th, 321, i.e. concrete drying shrinkage increases with the increase of sand coarse aggregate ratio, this causes coarse aggregate mainly due to sand coarse aggregate ratio increase Volume fraction reduces, so as to weaken to the inhibition of concrete shrinkage, final table 2- is existing to be increased for dry shrink.

Influence of the sand coarse aggregate ratio to creeping：Influence of the sand coarse aggregate ratio to concrete drying shrinkage is as shown in Fig. 2-62.Fig. 2-62 is glue Than 0.35, the creep degree rule of development of concrete during sand coarse aggregate ratio 36%, 39%, 42%.It can be seen from the above that sand coarse aggregate ratio creeps concrete Degree has certain influence, but influence degree is smaller for opposite water-cement ratio and flyash.Wherein sand coarse aggregate ratio 36% when coagulation Native creep degree is minimum, is 44.8 × 10^-6/ MPa, and when sand coarse aggregate ratio reaches 42%, creep degree then increases to 51.37 × 10^-6/ MPa, This is because sand coarse aggregate ratio is smaller, the ratio of coarse aggregate is relatively bigger in concrete, and skeleton of the coarse aggregate as concrete, its content It is bigger, it is also bigger to the inhibitory action of concrete shrinkage and creep, therefore sand coarse aggregate ratio is bigger, concrete creep is bigger.

Table 2-25 difference sand coarse aggregate ratio concrete 180d Creep Coefficients

Sp%	180d Creep Coefficients
		36	3.46
39	3.73
		42	3.96

Claims (7)

1. concrete construction method under a kind of low temperature difference environment, includes successively：The preparation of concrete, the transport of concrete, The tensioning of deformed bar, the binding of reinforcing bar, the pouring of concrete, the maintenance of concrete, it is characterised in that：

Wherein, the tensioning of deformed bar, process conditions are：Before tensioning, 1h is heated to the hydraulic oil in tensioning sump, and Jack is preheated；Tensioning selection carries out more than -5 DEG C, in tensioning, is heated under fuel tank, until tensioning is completed；

Wherein, the maintenance of concrete uses construction " heating house method ", and process conditions are：Concrete conserves in brooder, is set in brooder Stove or warm-air drier, more than 80%, maintenance 8-28d humid controls exist 7d humid controls temperature control before 15-40 DEG C, maintenance More than 50%；Steel form wraps up concrete, then insulating layer is set outside steel form, and form removal after 24h, uses plastics immediately after form removal Cloth, blanket or tarpaulin parcel conserve 28 days.

2. concrete construction method under a kind of low temperature difference environment according to claim 1, it is characterised in that：It is described mixed Solidifying soil is at least made of the component of following parts by weight：Cement, coarse aggregate, fine aggregate, mineral admixture, additive；The concrete In, gel rubber material dosage is 350kg/m³~500kg/m³, it is preferable that gel rubber material dosage is 400kg/m³~500kg/m³, more Preferably, C30 strength grades concrete gel material dosage is 380kg/m³, C40 strength grade concrete gel material dosages For 420kg/m³, C50 concrete gel materials dosage is 500kg/m³；

Sand coarse aggregate ratio is 33-42%, it is preferable that sand coarse aggregate ratio 39-41%, it is highly preferred that sand coarse aggregate ratio is 39%；

Mineral admixture volume is 0-30%, it is preferable that mineral admixture volume is 0-15%, it is highly preferred that mineral admixture Volume is 15%；

The volume of additive is 1.0~1.4%, preferably 1.0%；

Water-cement ratio is 0.34-0.48, it is preferable that water-cement ratio 0.34-0.40, it is highly preferred that C30 water-binder ratios are The water-cement ratio of 0.45, C40 concrete is that 0.40, C50 water-binder ratios are 0.34.

3. concrete construction method under a kind of low temperature difference environment according to claim 2, it is characterised in that：The water Mud is portland cement, ordinary portland cement, KS- slag cements, preferably FS- pulverized fuel ash cements, KS- slag cements；The cement Fineness is 280~402m²/ kg, preferably 335~402m²/kg。

4. concrete construction method under a kind of low temperature difference environment according to claim 2, it is characterised in that：It is described thick For the particle diameter to gather materials between 20-40mm, coarse aggregate elongated particles are 5-14%.

5. concrete construction method under a kind of low temperature difference environment according to claim 2, it is characterised in that：It is described thin The particle diameter to gather materials is between 0.16~5mm, its modulus of fineness is 2.5-3.2, clay content 1.5-3.5%, it is preferable that fineness mould Number is 3.0, clay content 2%.

6. concrete construction method under a kind of low temperature difference environment according to claim 2, it is characterised in that：The ore deposit Polymer blends material for flyash, graining blast-furnace cinder micro-powder, silicon ash, zeolite rock powder, agstone, one kind in natural volcanic ash or It is several, preferably Class F fly ash or high-calcium fly ass, more preferably high-calcium fly ass, most preferably I grades of high-calcium fly ass.

7. concrete construction method under a kind of low temperature difference environment according to claim 2, it is characterised in that：It is described outer Agent is added to include the one or more in water-reducing agent, adjustable solidification agent, waterproofing agent, air entraining agent；The water-reducing agent include polycarboxylate water-reducer, Naphthalene water reducer, preferably polycarboxylate water-reducer；The volume of the water-reducing agent is 1.0~1.4%, preferably 1.0%.