CN103787628A - Preparation method of low-temperature early strength concrete for high cold permafrost region tunnel - Google Patents
Preparation method of low-temperature early strength concrete for high cold permafrost region tunnel Download PDFInfo
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Abstract
The invention discloses a preparation method of low-temperature early strength concrete for a high cold permafrost region tunnel, which comprises the following steps: selection of formula materials of the low-temperature early strength concrete, proportion design, stirring, transportation, pouring, mould removal, maintenance and quality inspection and control, wherein the proportion is designed as follows: the water-cement ratio is 0.43-0.48, the cement dosage is 360-400kg/m<3>, the sand ratio is 38-42%, the water dosage is 165-180, the dosage of a composite early strength water reducing agent is 3% of the cement dosage, and the dosage of an anti-freezing agent is 3% of the cement dosage at -15 DEG C. A routine test and a low-temperature test are made in proportion design. By adopting the method disclosed by the invention, the concrete has the ability of supporting the surrounding rock within the set time under a low-temperature condition, the time limit that a frozen-soil tunnel is only suitable for cold season construction is overcome, various heating measures are adopted on the construction site, the construction of plateau frozen-soil tunnels can be realized all year round, and the aims of economical efficacy and controllable quality are achieved.
Description
Technical field
the technology of the present invention relates to tunnel concrete construction field, particularly relates to a kind of for highland and severe cold tunnel ever frost section, tunnel portal and exposed structure concrete construction concrete formulating method.
Background technology
4715 meters of La Shan tunnel, Hubei Province total lengths, Sui Zhi district belongs to high mountain in periglacial and structural erosion, and topographic relief is larger, and height above sea level, between 4300-4600m, belongs to Permafrost Area, and barrel top covers ever frost layer, permafrost region upper limit 1.4-1.8m; Lower limit 35-36m, top frozen water stores ever frost layer is to contain the gravelly soil of mild clay take many ice, Fu Bing, full freezing soil as main; Average temperature of the whole year-4.2 ℃, La Shan tunnel, Hubei Province, 26.6 ℃ of Extreme Maximum Temperatures, the extreme lowest temperature-48.1 ℃.
under severe like this condition, carry out a Permafrost Area concrete construction technology difficult problem urgently to be resolved hurrily.La Shan tunnel, Hubei Province ever frost section is designed to low-temperature high-early strength concrete, require the heat minimum of bringing into should guarantee to build in concrete construction time to make hydration heat temperature rise unlikely to frozen soil layer structure generation destruction, guarantee that again concrete can normally harden and before temperature is down to subzero temperature, reach freeze proof critical strength under cold condition.
if manifest and can not meet the requirement of concrete low-temperature high-early strength according to design of common concrete proportioning and construction, taking low-temperature high-early strength concrete technology is the important measures concerning La Shan tunnel, Hubei Province frozen soil section construction safety, quality, duration and benefit.
Summary of the invention
the technical problem that the technology of the present invention will solve is: a kind of low-temperature high-early strength concrete formulating method for tunnel, high and cold Permafrost Area is provided, concrete is reached at cold condition, in the specified time and support the ability of country rock, realize economic efficacy and quality controllable object.
the technical solution adopted in the present invention is:
comprise that the concrete formula materials of low-temperature high-early strength selects, mix-design, stirs, transports, builds, form removal and maintenance, quality test and control; Wherein mix-design is:
(1) water cement ratio: 0.43-0.48;
(2) cement consumption: 360-400kg/m3;
(3) sand coarse aggregate ratio: 38-42%;
(4) water consumption: 165-180;
(5) slump: 160-200mm;
(6) composite high-early strength water reducer volume: account for cement mixing content 3%;
(7)-15 ℃, the amount of blended concrete antifreezing agent: account for cement mixing content 3%.
when mix-design, do routine test and low-temperature test; Routine test is: in the time of trial mix concrete, select sand, rubble, cement to be all controlled at 5-10 ℃, calculate with regulating the mode of water temperature that Concrete temperature is controlled to 8-13 ℃ of left and right by thermal technology, make normal curing in 3,7,28 days and real curing and protect ultimate compression strength test block, ultimate compression strength is done to growth comparative analysis, make impervious test block simultaneously and do anti-permeability performance test; Low-temperature test is: trial mix is made corresponding test block and carried out subzero temperature test, and the test block after moulding is first treated its initial set at the indoor standing 2-4 hour of 20 ℃, then puts into and takes out afterwards for 7 days of cryostat maintenance, proceeds to mark and supports chamber continuation maintenance 28 days, 56 days; Cryostat temperature is got-15 ℃ according to site environment temperature and site operation measure.
stir, transport, build, form removal and maintenance comprise following content:
1) mixing station setting: with two HD900 type forced mixer central mix concretes, and be equipped with 2 ZL50 type shovel loader material loadings, 6 8m3 concrete delivery trucks transport, and mixing station throughput can reach 60m3/h;
2) starting material insulation: whipping device, admixture are placed in airtight color steel room, sand, building stones classification, a point storehouse are stacked in steel construction heat preservation greenhouse; Adopt the heat supply respectively of two coal burning boilers, wherein the boiler of 5 tons is the heating of concrete mixing water specially, and mixing water heating and temperature control is at 30-60 ℃; It is sand, building stones, admixture, mechanical means Heat preservation that the boiler of 10 tons is taked the mode of pipe heat-transfer, radiator, and temperature maintains 5-10 ℃;
3) concrete mixing: before each concrete mixing, carry out water ratio detection from the sampling of fine aggregate feed bin upper, middle and lower and average, and construction proportioning related data is confirmed; Cement, admixture and water, aggregate after heating should measure respectively, and its error in dipping is controlled at: cement, water, admixture are 1%, and aggregate is 2%; Should adjust feeding sequence when water temperature during higher than 60 ℃, make water first with aggregate premixing and then drop into cement, admixture formally stirs; The concrete-agitating time should be lower than 120S; Consider that concrete has calorific loss in transportation, is controlled at 10-15 ℃ by concrete out-of-machine temperature;
4) concrete transportation with build: take concrete delivery truck transportation, add the cotton stay-warm case of making of one layer of heat preservation outward at stirring barrel of concrete transport vehicle; In concrete transportation process, should keep slowly running of 2-4r/min, should build immediately after being transported to the scene of building, the residence time can not exceed 2 hours.When casting concrete, should measure concrete molding temperature, guarantee that temperature maintains 5-10 ℃, the symmetrical placement layer by layer in both sides, every layer thickness is preferably 30cm-50cm, and makes firm by ramming closely knit with poker vibrator;
5) concrete form removal and maintenance: concrete composition material is heated to rear stirring, concrete is leaving Yu Wen after transportation is vibrated, concrete after building around covers with lagging material, utilize the heat of the remaining temperature of concrete and hydration heat of cement, make the concrete sclerosis gradually in Slow cooling process after building, reached in the past freeze proof critical strength when concrete drops to 0 ℃.
low-temperature high-early strength once lining concrete reaches 70% form removal of design strength, more than length of time 48h; Under subzero temperature condition, forbid in concrete surface watering, and curing temperature must not be lower than the temperature of frostproofer regulation; In the time that concrete surface and the extraneous temperature difference are greater than 20 ℃, should adopt immediately plastics film parcel Concrete Anti sealing to divide evaporation, then add lagging material and cover and make its slow cooling maintenance 7-14 days.
the content of quality test and control is: 1) raw material quality check; 2) concrete work performance check; 3) temperature measuring and control; 4) maturing quality test.
before raw material quality check comprises use, grating, silt content, faller gill shape granule content are rechecked; Also comprise admixture test, detect the water-reducing rate of admixture, the antifreezing effect of frostproofer.
the check of concrete work performance comprises the check fresh concrete slump, observes concrete glutinous poly-property, water-retentivity; Detect air content that concrete arrives working-yard whether within 4%-6% scope.
temperature measuring and Control the content comprise: temperature, raw material temperature, concrete out-of-machine temperature in free air temperature, stirring station, build the temperature of making rear temperature firm by ramming, building post-hardening.
maturing quality test be included in build on-the-spot randomly draw to make with proportioning concrete by every shift or 100m3 be no less than one group of standardized test sample of maintenance, also should make the strength of mould stripping that protects with structure real curing, f-7+28 days, 28 days test specimens; Produce impervious, freeze-thaw-circulation test specimen by standard, all kinds of test specimen performance test results and design requirements are contrasted and carry out qualification determination.
low-temperature high-early strength mix Design principle: first meet design document ultimate compression strength, impervious and freeze-thaw-cycle indicator requirement; Its less important assurance concrete obtains enough freeze proof critical strengties at the appointed time, makes it not suffer freeze injury; Serviceability and strength of mould stripping will meet pumping concrete construction requirement again; Will consider the impact on frozen soil of heat that concrete discharges in process of setting, simulated field execution conditions and weather condition carry out the concrete preparation of low-temperature high-early strength simultaneously.
for guaranteeing to go out qualified concrete according to design document requirement mixing, aspect concrete mixing station setting, starting material insulation, formulating detailed planning, and at low-temperature high-early strength concrete mixing, transport, build, maintenance, the surely corresponding measure of quality check system.
the technology of the present invention in actual use, has following actual effect:
(1) solved normal concrete and do not taked Insulation normally to build at cold condition, built rear concrete and cannot reach at the appointed time freeze proof critical strength and form the problem that supports country rock ability.
(2) overcome the only suitable limitation of the time at construction in cold season of frozen soil tunnel in the past, realized Plateau permafrost tunnel and all can construct the whole year.
(3) avoided taking normal concrete when construction scene to set up brooder insulation makes envrionment temperature while that raises produce heat when concrete coagulation in the hole in, cause frozen soil section preliminary bracing frozen soil layer generation behind to be melted and cause that freeze thawing circle expands, and guarantees construction quality and the safety of frozen soil section.
(4) insulation, intensification measure can not taked in scene when concrete placement, have reduced the production cost that auxiliary construction Insulation increases.
(5) concrete demoulding time advance, has shortened the lining trolley turnover time, meets the construction principle of frozen soil section " fast supporting, tight lining cutting ", has guaranteed the realization of interim duration target simultaneously.
figure of description:
fig. 1 is that real curing of the present invention protects m-strength relationship graphic representation of 5 ℃ of concrete molding temperatures-time;
fig. 2 is that real curing of the present invention protects m-strength relationship graphic representation of 10 ℃ of concrete molding temperatures-time;
fig. 3 is that real curing of the present invention protects 5 ℃ of concrete m-strength relationship graphic representation of molding temperature-time.
embodiment:
embodiments of the invention: comprise that for the low-temperature high-early strength concrete formulating method in tunnel, high and cold Permafrost Area the concrete formula materials of low-temperature high-early strength selects, mix-design, stirs, transports, builds, form removal and maintenance, quality test and control.
one, raw material selection
1, admixture: select the Shanxi liquid compound early strength water-reducing agent of letter Xiang HXFDN (to comprise diminishing component, accelerating component, bleed component, determine that through testing air content is controlled within the scope of 4%-6% according to code requirement), make in 1:2 ratio is composite with polycarboxylate high performance water-reducing agent and hardening accelerator, its water-reducing rate reaches more than 25%, not only can improve concrete serviceability, also reduced the liquid water in concrete mix, concrete early strength under cold condition of mixing general water reducer and not mixing water reducer increasess slowly, can not meet the requirement of low-temperature high-early strength concrete, concrete early strength rate of increase under cold condition of mixing polycarboxylate high performance water-reducing agent is still very high, and polycarboxylate high performance water-reducing agent itself possesses air-entraining function, can in concrete, introduce a large amount of micro-bubbles reduce concrete in freeze-thaw cycle because volumetric shrinkage changes the destroying concrete structure causing, strengthen concrete Frost Resistance energy.Its accelerating component can accelerate hydrated reaction of cement, shortens concrete coagulating time raising early strength and allows to obtain as soon as possible freeze proof critical strength value.(performance index are in table 1)
2, frostproofer: according to Hubei Province La Shan temperature condition and construction environment, select Shanxi letter Xiang HXFDJ(-15 ℃) frostproofer, antifreeze composition can make the water molecules in concrete be unlikely to congeal into ice or few freezing in subzero temperature condition, ensures enough liquid water molecules and makes concrete under subzero temperature condition, normal aquation form gain in strength.(performance index are in table 2)
3, cement: according to the concrete construction characteristic of low-temperature high-early strength and requirement, the concrete of subzero temperature condition construction should preferentially be selected cement type or the model that thermal value is large, hydration reaction is fast, early strength is high, through overtesting, than choosing, we select the gold circle board normal silicate short-term strength cement (P.O42.5R) of Xining production; This cement has good adaptability through test with admixture, and its early strength is high, time of coagulation is fast, meets low-temperature high-early strength early age strength of concrete and increases fast requirement.(performance index are in table 3)
4, by investigation, sampling test comparison on the spot, select washing river, sand field, blue or green root river sand, this chiltern ground, Sha Chang river is hard, grating good (II district sand), particle cleaning, and indices all meets JTG F60-2009 " highway tunnel construction technical specifications " requirement.
, select the rubble of the 5-31.5 ㎜ producing along prosperous rubble field, this rubble adopts two-stage crushing 5-20 ㎜, two kinds of specification single-stage rubbles of 16-31.5 ㎜, through press 4:6 than the synthetic 5-31.5 ㎜ continuous grading of row, the concrete that assurance prepares out has good workability; Indices all meets JTG F60-2009 " highway tunnel construction technical specifications " requirement.
, Sui Zhi district river water, meet the requirement of concrete mixing water through check.
two, mix-design
1, low-temperature high-early strength mix Design, first must meet design document ultimate compression strength C30, impervious S10 and freeze-thaw-circulation F300 grade standard; Its less important assurance concrete obtains enough freeze proof critical strengties at the appointed time; According to JTG/T F50-2011 " highway bridge and culvert construction technique normalizing " requirement, adopt the concrete of silicate cement or ordinary Portland cement preparation, can not suffer freeze injury reached 12MPa before ultimate compression strength reaches design strength value 40% before; The on-the-spot temperature condition of our construction simulation, carries out the adjustment of C30 low-temperature high-early strength mix Design by following parameter area for this reason.
water cement ratio (W/C): 0.43-0.48
(2) cement consumption (C): 360-400kg/m3
(3) sand coarse aggregate ratio (SP): 38-42%
(4) water consumption (W): 165-180
(5) slump: 160-200mm
(6) composite high-early strength water reducer volume: cement mixing content 3%
(7) the amount of blended concrete antifreezing agent (15 ℃): cement mixing content 3%
2, cold test: examination timing we according to Hubei Province La Shan constructing tunnel and mixing station heat-retaining condition, in the time of trial mix concrete, select sand, rubble, cement to be all controlled at 5-10 ℃, calculate with regulating the mode of water temperature that Concrete temperature is controlled to 8-13 ℃ of left and right by thermal technology, make normal curing in 3,7,28 days and real curing and protect ultimate compression strength test block, ultimate compression strength is done to growth comparative analysis; Make impervious test block simultaneously and do anti-permeability performance test.
, low-temperature test: trial mix is made corresponding test block and is carried out subzero temperature test, test block after moulding is first treated its initial set at the indoor standing 2-4 hour of 20 ℃, then put into and take out afterwards for 7 days of cryostat (cryostat temperature is got-15 ℃ according to site environment temperature and site operation measure) maintenance, proceed to mark and support chamber continuation maintenance 28 days, 56 days.As f-7+56≤f28 and f28≤fp (intensity is joined in examination), and simulated field temperature condition is made with the test block of condition strength of mould stripping as striking time foundation, concrete impermeability, freeze-thaw-cycle performance meet design requirement simultaneously, this proportioning can be used for construction, otherwise should re-start mix-design.
, determine theoretical proportioning: according to design and construction requirement, by above-mentioned definite parameter area, Related Formula with " design of common concrete proportioning rules " calculates preliminary proportioning, try to join with preliminary proportioning, and join concrete serviceability according to examination and carry out suitable adjustment and draw theoretical proportioning, theoretical proportioning is kept in the constant situation of water consumption, carry out upper and lower water cement ratio and float 0.05 with reference to Mix Ratio Test, compressive strength test result with three proportionings is made W/C-f7, relation curve between W/C-f28, finally determine that according to the relation curve of orthogonal test the theoretical proportioning folk prescription material usage of construction is:
cement: 387 ㎏, sand: 741 ㎏, rubble: 1112 ㎏, water: 157 ㎏, composite high-early strength water reducer: 11.61 ㎏, frostproofer: 11.61 ㎏.(performance index are in table 4)
three, concrete-agitating, transport, build, form removal and maintenance
1, mixing station setting: with two HD900 type forced mixer central mix concretes, and be equipped with 2 ZL50 type shovel loader material loadings, 6 8m3 concrete delivery trucks transport, and mixing station throughput can reach 60m3/h.; Stirring station is established 1 responsible daily management mission of the head of a station, and configuring 1 of full-time scheduling, 2 of testing crews, 1 of m of e personnel, other staff configure on demand, and set up detailed management system and quality certification system, the strict error in dipping of controlling, guarantees to construct by proportioning.
, starting material insulations: whipping device, admixture are placed in airtight color steel room, and sand, building stones classification, a point storehouse are stacked in steel construction heat preservation greenhouse; Adopt the heat supply respectively of two coal burning boilers, wherein the boiler of 5 tons is the heating of concrete mixing water specially, and mixing water Heating temperature is controlled at 30-60 ℃ according to surveying sand, building stones, cement, admixture temperature the same day after thermal technology's calculating; It is sand, building stones, admixture, mechanical means Heat preservation that the boiler of 10 tons is taked the mode of pipe heat-transfer, radiator, and temperature maintains 5-10 ℃.
, concrete mixing: before each concrete mixing, testing crew should carry out water ratio from the sampling of fine aggregate feed bin upper, middle and lower and detect and averages, and reply construction proportioning related data is confirmed.Cement, admixture and water, aggregate after heating should measure respectively, and its error in dipping is controlled at: cement, water, admixture are 1%, and aggregate is 2%.Should adjust feeding sequence when water temperature during higher than 60 ℃, make water first with aggregate premixing and then drop into cement, admixture formally stirs; The concrete-agitating time should be lower than 120S; Consider that concrete has calorific loss in transportation, is controlled at 10-15 ℃ by concrete out-of-machine temperature.
, concrete transportation and building: take concrete delivery truck transportation, add the cotton stay-warm case of making of one layer of heat preservation outward at stirring barrel of concrete transport vehicle.In concrete transportation process, should keep slowly running of 2-4r/min, should build immediately after being transported to the scene of building, the residence time can not exceed 2 hours.When casting concrete, should measure concrete molding temperature, guarantee that temperature maintains 5-10 ℃, the symmetrical placement layer by layer in both sides, every layer thickness is preferably 30cm-50cm, and makes firm by ramming closely knit with poker vibrator.
, concrete form removal and maintenance: due to the singularity of Hubei Province La Shan constructing tunnel, low-temperature high-early strength concrete is taked regenerative process maintaining process, namely concrete composition material is heated to rear stirring, concrete is leaving certain remaining temperature after transportation is vibrated, concrete after building around covers with lagging material, utilize the heat of the remaining temperature of concrete and hydration heat of cement, make the concrete sclerosis gradually in Slow cooling process after building, reached in the past freeze proof critical strength when concrete drops to 0 ℃.
low-temperature high-early strength once lining concrete reaches 70% of design strength can form removal, and more than length of time 48h, the concrete time is as the criterion with maintaining test block with same condition compression strength value; Under subzero temperature condition, forbid in concrete surface watering, and curing temperature must not be lower than the temperature of frostproofer regulation; In the time that concrete surface and the extraneous temperature difference are greater than 20 ℃, should adopt immediately plastics film parcel Concrete Anti sealing to divide evaporation, then add lagging material and cover and make its slow cooling maintenance 7-14 days.
four, quality control and test
1, raw material quality check: concrete raw material quality control is the key of concrete inner quality, and cement should be strictly by the lot inspection of marching into the arena, and the cement that exceedes the storage time firmly stops to be used in low-temperature high-early strength concrete.Slightly, fine aggregate should, by different varieties, the storage of specification classify and pile up, be tackled the indexs such as grating, silt content, faller gill shape granule content before using and recheck after marching into the arena.Every batch of admixture of marching into the arena all needs to test, and particularly whether the antifreezing effect of the water-reducing rate of admixture, frostproofer reaches code requirement, and concrete quality is played a crucial role.Thereby water-reducing rate does not reach and certainly will strengthen concrete mixing water consumption and improve water cement ratio and reduce concrete ultimate compression strength, and frostproofer does not reach regulation subzero temperature value, affects concrete freeze proof threshold value, even destroys concrete structure.
, concrete work performance: each fresh concrete all should be checked the slump; and observe the performances such as concrete glutinous poly-property, water-retentivity; find that concrete does not reach requirement and should carry out suitable adjustment; its properties is controlled in design allowed band, guarantees that concrete work performance meets construction needs.Guarantee that concrete duration of mixing meets 120S; because the bleed composition of polycarboxylate high performance water-reducing agent starts 1-2min and rises; the 2-3min state that reaches capacity; stirring air content declines on the contrary again; consider that concrete concrete tank in transportation also needs not stop rotation; determine that the concrete mixing time is that 120S is more reasonable, the air content that its concrete arrives working-yard is after testing within design 4%-6% scope.
, temperature measuring and control
for guaranteeing the concrete construction quality of low-temperature high-early strength, in concrete mixing, build, should establish special messenger in moulding and maintenance processes temperature is measured, and according to the temperature results of measuring, construction process is carried out to suitable adjustment, the temperature content of measurement comprises: temperature, raw material temperature, concrete out-of-machine temperature in free air temperature, stirring station, build the temperature of making rear temperature firm by ramming, building post-hardening.
free air temperature is often divided 02,08,14,20 o'clock totally 4 times round the clock, separately adds that survey is the highest, the lowest temperature.
in stirring station, temperature adopts and hangs liquid-type thermometer, and every shift is estimated 4 times.
raw material temperature adopts infrared thermometer to measure, and in concrete opening quotation pre-test once, measures once at interval of 2 hours later.
concrete out-of-machine temperature and molding temperature adopt insert temperature measurer per car to measure once.
temperature after concrete placement is vibrated adopts insert temperature measurer to measure once for every 2 hours.
concrete placement post-hardening temperature adopts the mode thermometric of pre-buried electronic temperature measurement probe, and thermometer hole symmetry is embedded in position, lining concrete upper, middle and lower, and thermometer hole is numbered to record; From build complete up to concrete strength reach freeze proof threshold value every 4 hours measure once.
, maturing quality test
low-temperature high-early strength concrete success key is to reach at the appointed time freeze proof threshold value, build on-the-spot randomly draw to make with proportioning concrete by every shift or 100m3 be no less than one group of standardized test sample of maintenance, also should make the strength of mould stripping that protects with structure real curing, f-7+28 days, 28 days test specimens.Also should make if necessary 3 days, 7 days, strength of mould stripping real curing and protect test specimen, analyze concrete strength rising tendency, produce impervious, freeze-thaw-circulation test specimen by standard, all kinds of test specimen performance test results and design requirements are contrasted and carry out qualification determination.
at the low-temperature high-early strength concrete that completes the construction of ever frost section, through sampling test evaluate its intensity and impervious, freeze-thaw-index is all qualified, concrete mix through republicanism to central laboratory of cajaput road construction headquarters, Jiangsu Research Institute of Communication, management testing laboratory of traffic engineering consulting and design institute of Qinghai Province checking proportioning and scene randomly draw test specimen, its result all reaches design requirements.
by facts have proved, to select high-performance compound water reducer, the frostproofer that subzero temperature is suitable, the short-term strength cement that adaptability is good in plateau permafrost tunnel concrete construction key, and select the good quality clean sand of grating, building stones, simulated field construction temperature condition makes the proportioning of works fine performance; Formulate practicable arrangement and method for construction, must take to concentrate the mode of mix, in concrete construction, to note strengthening especially the control of temperature, accomplish special messenger's supervision and management such as starting material insulation, mixing water heating, concrete out-of-machine temperature molding temperature, concrete work performance, can reach at the appointed time freeze proof critical strength and strength of mould stripping after guaranteeing to demonstrate,prove concrete placement.Concrete successfully utilization of this project low-temperature high-early strength has good reference role to relevant highlands low-temperature high-early strength concrete construction.
the subordinate list that above content relates to is as follows:
Claims (9)
1. for the low-temperature high-early strength concrete formulating method in tunnel, high and cold Permafrost Area, comprise that the concrete formula materials of low-temperature high-early strength selects, mix-design, stirs, transports, builds, form removal and maintenance, quality test and control; Wherein mix-design is:
(1) water cement ratio: 0.43-0.48;
(2) cement consumption: 360-400kg/m3;
(3) sand coarse aggregate ratio: 38-42%;
(4) water consumption: 165-180;
(5) slump: 160-200mm;
(6) composite high-early strength water reducer volume: account for cement mixing content 3%;
(7)-15 ℃, the amount of blended concrete antifreezing agent: account for cement mixing content 3%.
2. the low-temperature high-early strength concrete formulating method for tunnel, high and cold Permafrost Area according to claim 1, is characterized in that: when mix-design, do routine test and low-temperature test; Routine test is: in the time of trial mix concrete, select sand, rubble, cement to be all controlled at 5-10 ℃, calculate with regulating the mode of water temperature that Concrete temperature is controlled to 8-13 ℃ of left and right by thermal technology, make normal curing in 3,7,28 days and real curing and protect ultimate compression strength test block, ultimate compression strength is done to growth comparative analysis, make impervious test block simultaneously and do anti-permeability performance test; Low-temperature test is: trial mix is made corresponding test block and carried out subzero temperature test, and the test block after moulding is first treated its initial set at the indoor standing 2-4 hour of 20 ℃, then puts into and takes out afterwards for 7 days of cryostat maintenance, proceeds to mark and supports chamber continuation maintenance 28 days, 56 days; Cryostat temperature is got-15 ℃ according to site environment temperature and site operation measure.
3. the low-temperature high-early strength concrete formulating method for tunnel, high and cold Permafrost Area according to claim 1, is characterized in that: stir, transport, build, form removal and maintenance comprise following content:
1) mixing station setting: with two HD900 type forced mixer central mix concretes, and be equipped with 2 ZL50 type shovel loader material loadings, 6 8m3 concrete delivery trucks transport, and mixing station throughput can reach 60m3/h;
2) starting material insulation: whipping device, admixture are placed in airtight color steel room, sand, building stones classification, a point storehouse are stacked in steel construction heat preservation greenhouse; Adopt the heat supply respectively of two coal burning boilers, wherein the boiler of 5 tons is the heating of concrete mixing water specially, and mixing water heating and temperature control is at 30-60 ℃; It is sand, building stones, admixture, mechanical means Heat preservation that the boiler of 10 tons is taked the mode of pipe heat-transfer, radiator, and temperature maintains 5-10 ℃;
3) concrete mixing: before each concrete mixing, carry out water ratio detection from the sampling of fine aggregate feed bin upper, middle and lower and average, and construction proportioning related data is confirmed; Cement, admixture and water, aggregate after heating should measure respectively, and its error in dipping is controlled at: cement, water, admixture are 1%, and aggregate is 2%; Should adjust feeding sequence when water temperature during higher than 60 ℃, make water first with aggregate premixing and then drop into cement, admixture formally stirs; The concrete-agitating time should be lower than 120S; Consider that concrete has calorific loss in transportation, is controlled at 10-15 ℃ by concrete out-of-machine temperature;
4) concrete transportation with build: take concrete delivery truck transportation, add the cotton stay-warm case of making of one layer of heat preservation outward at stirring barrel of concrete transport vehicle; In concrete transportation process, should keep slowly running of 2-4r/min, should build immediately after being transported to the scene of building, the residence time can not exceed 2 hours; When casting concrete, should measure concrete molding temperature, guarantee that temperature maintains 5-10 ℃, the symmetrical placement layer by layer in both sides, every layer thickness is preferably 30cm-50cm, and makes firm by ramming closely knit with poker vibrator;
5) concrete form removal and maintenance: concrete composition material is heated to rear stirring, concrete is leaving Yu Wen after transportation is vibrated, concrete after building around covers with lagging material, utilize the heat of the remaining temperature of concrete and hydration heat of cement, make the concrete sclerosis gradually in Slow cooling process after building, reached in the past freeze proof critical strength when concrete drops to 0 ℃.
4. the low-temperature high-early strength concrete formulating method for tunnel, high and cold Permafrost Area according to claim 3, is characterized in that: low-temperature high-early strength once lining concrete reaches 70% form removal of design strength, more than length of time 48h; Under subzero temperature condition, forbid in concrete surface watering, and curing temperature must not be lower than the temperature of frostproofer regulation; In the time that concrete surface and the extraneous temperature difference are greater than 20 ℃, should adopt immediately plastics film parcel Concrete Anti sealing to divide evaporation, then add lagging material and cover and make its slow cooling maintenance 7-14 days.
5. the low-temperature high-early strength concrete formulating method for tunnel, high and cold Permafrost Area according to claim 1, is characterized in that: the content of quality test and control is: 1) raw material quality check; 2) concrete work performance check; 3) temperature measuring and control; 4) maturing quality test.
6. the low-temperature high-early strength concrete formulating method for tunnel, high and cold Permafrost Area according to claim 5, is characterized in that: before raw material quality check comprises use, grating, silt content, faller gill shape granule content are rechecked; Also comprise admixture test, detect the water-reducing rate of admixture, the antifreezing effect of frostproofer.
7. the low-temperature high-early strength concrete formulating method for tunnel, high and cold Permafrost Area according to claim 5, is characterized in that: the check of concrete work performance comprises the check fresh concrete slump, observes concrete glutinous poly-property, water-retentivity; Detect air content that concrete arrives working-yard whether within 4%-6% scope.
8. the low-temperature high-early strength concrete formulating method for tunnel, high and cold Permafrost Area according to claim 5, is characterized in that: temperature measuring and Control the content comprise: temperature, raw material temperature, concrete out-of-machine temperature in free air temperature, stirring station, build the temperature of making rear temperature firm by ramming, building post-hardening.
9. the low-temperature high-early strength concrete formulating method for tunnel, high and cold Permafrost Area according to claim 5, it is characterized in that: maturing quality test be included in build on-the-spot randomly draw to make with proportioning concrete by every shift or 100m3 be no less than one group of standardized test sample of maintenance, also should make the strength of mould stripping that protects with structure real curing, f-7+28 days, 28 days test specimens; Produce impervious, freeze-thaw-circulation test specimen by standard, all kinds of test specimen performance test results and design requirements are contrasted and carry out qualification determination.
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| CN104960088A (en) * | 2015-06-16 | 2015-10-07 | 乌海市公路工程有限公司 | Method for improving curve box girder appearance quality in high-temperature-difference region |
| CN105525615A (en) * | 2014-11-12 | 2016-04-27 | 葛洲坝集团第一工程有限公司 | Quick slurry feeding method for backfill grouting |
| CN106442035A (en) * | 2016-05-18 | 2017-02-22 | 中国能源建设集团甘肃省电力设计院有限公司 | Production apparatus and production method for concrete-frozen soil contact surface direct shear test sample |
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| CN109899091B (en) * | 2019-03-27 | 2021-04-16 | 中南大学 | Reverse control method for material ratio of mixing station |
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| CN113896469A (en) * | 2021-11-17 | 2022-01-07 | 中电建十一局工程有限公司 | Large-volume high-strength concrete |
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