CN103803916B - A kind of strength grade granite powder concrete being not more than C40 and preparation method thereof - Google Patents

Abstract

The invention discloses granite powder concrete and preparation technology thereof that a kind of strength grade is not more than C40, wherein said granite powder concrete is prepared from primarily of gelling material, water, sand, rubble and extra material, described gelling material is cement and granite stone powder, or be cement, breeze and granite stone powder, described extra material is water reducer.The granite powder concrete utilizing the present invention to prepare, is all better than conventional concrete meeting in the early anti-cracking behavior under requirement of strength prerequisite, Anti-Chloride Ion Penetration, anti-carbonation properties etc.

Description

A kind of strength grade granite powder concrete being not more than C40 and preparation method thereof

Technical field

The invention belongs to technical field of concrete, relate to a kind of granite powder concrete using cement, breeze, granite stone powder and polycarboxylic admixture composite voluntarily to prepare strength grade to be not more than C40 grade.

Background technology

Since the thirties in 20th century, concrete mainly with flyash and breeze for Additive, not only decrease cement consumption, and improve concrete intensity, also enhance concrete weather resistance.But in recent years along with the fast development of the industries such as construction of hydropower facilities, work China Democratic National Construction Association, flyash and breeze demand increase rapidly, and supply falls short of demand often.In this case, seek a kind of easy acquisition, high-quality cheapness alternative adulterant imperative.

In recent years, along with the exhaustion of natural sand resource, the application of artificial sand is more and more general, creates new waste and stone flour thereupon.Artificial sand is mainly raw material with grouan, and the granite stone powder produced so far utilization ratio is lower.Major cause has:

1, first granite stone powder is different from calcium carbonate is main component purposes marble stone flour more widely, and composition is comparatively complicated, and undressed granite stone powder activity is lower;

2, it two lacks research to granite stone powder correlation theory, reaction mechanism.

The application of stone flour in concrete becomes a kind of trend gradually.Limestone powder is used as cement mixture and concrete admixture is the focus studied both at home and abroad at present.In June in this year, People's Republic of China's house and town and country construction portion have issued " limestone powder is utilisation technology code in concrete " suggestion and have solicited original text, for the use of limestone powder provides canonical reference.

Fine powder and stone flour that the machined rear particle of rubble is less than 0.16 millimeter produce one of cement, the ideal material preparing high performance concrete.In stone flour, particle diameter is less than siliceous, the calcareous particle of 0.045mm, has the hydrated product of some strength, filling concrete pore, makes concrete hole refinement, reduces concrete porosity, improve concrete pore texture, thus improve concrete performance.

Summary of the invention

A kind of strength grade is the object of the present invention is to provide to be not more than granite powder concrete and the preparation technology thereof of C40.The granite powder concrete utilizing the present invention to prepare, is all better than conventional concrete meeting in the early anti-cracking behavior under requirement of strength prerequisite, Anti-Chloride Ion Penetration, anti-carbonation properties etc.

In order to realize above-mentioned purpose of the present invention, contriver is studied by lot of experiments and explores, and finally obtains following technical scheme:

A kind of strength grade is not more than the granite powder concrete of C40, wherein said granite powder concrete is prepared from primarily of gelling material, water, sand, rubble and extra material, described gelling material is cement and granite stone powder, or be cement, breeze and granite stone powder, described extra material is water reducer.

Preferably, strength grade as above is not more than the granite powder concrete of C40, wherein:

When strength grade is C15, described granite powder concrete is prepared from by the raw material of following parts by weight: cement 145 ~ 155 parts, granite stone powder 155 ~ 170 parts, 750 ~ 800 parts, sand, rubble 1000 ~ 1100 parts, 100 ~ 160 parts, water, water reducer 3 ~ 6 parts;

When strength grade is C20, described granite powder concrete is prepared from by the raw material of following parts by weight: cement 185-200 part, breeze 25 ~ 32 parts, granite stone powder 85 ~ 95 parts, 750 ~ 810 parts, sand, rubble 1000 ~ 1100 parts, 110 ~ 160 parts, water, water reducer 4 ~ 7 parts;

When strength grade is C25, described granite powder concrete is prepared from by the raw material of following parts by weight: cement 230 ~ 250 parts, breeze 45 ~ 60 parts, granite stone powder 75 ~ 90 parts, 730 ~ 800 parts, sand, rubble 900 ~ 1100 parts, 140 ~ 180 parts, water, water reducer 5 ~ 8 parts;

When strength grade is C30, described granite powder concrete is prepared from by the raw material of following parts by weight: cement 230 ~ 250 parts, breeze 110 ~ 130 parts, granite stone powder 180 ~ 210 parts, 630 ~ 700 parts, sand, rubble 900 ~ 1000 parts, 130 ~ 200 parts, water, water reducer 7 ~ 11 parts;

When strength grade is C35, described granite powder concrete is prepared from by the raw material of following parts by weight: cement 280 ~ 320 parts, breeze 120 ~ 150 parts, granite stone powder 90 ~ 130 parts, 650 ~ 750 parts, sand, rubble 900 ~ 1000 parts, 140 ~ 200 parts, water, water reducer 8 ~ 11 parts;

When strength grade is C40, described granite powder concrete is prepared from by the raw material of following parts by weight: cement 300 ~ 350 parts, breeze 130 ~ 160 parts, granite stone powder 100 ~ 130 parts, 600 ~ 700 parts, sand, rubble 850 ~ 950 parts, 150 ~ 200 parts, water, water reducer 10 ~ 12 parts.

Further preferably, strength grade as above is not more than the granite powder concrete of C40, wherein:

When strength grade is C15, described granite powder concrete is prepared from by the raw material of following parts by weight: cement 151 parts, granite stone powder 162 parts, 774 parts, sand, rubble 1063 parts, 134 parts, water, water reducer 5 parts;

When strength grade is C20, described granite powder concrete is prepared from by the raw material of following parts by weight: cement 193 parts, breeze 28 parts, granite stone powder 89 parts, 791 parts, sand, rubble 1049 parts, 135 parts, water, water reducer 5.5 parts;

When strength grade is C25, described granite powder concrete is prepared from by the raw material of following parts by weight: cement 238 parts, breeze 51 parts, granite stone powder 82 parts, 765 parts, sand, rubble 1014 parts, 167 parts, water, water reducer 6.8 parts;

When strength grade is C30, described granite powder concrete is prepared from by the raw material of following parts by weight: cement 239 parts, breeze 119 parts, granite stone powder 192 parts, 663 parts, sand, rubble 937 parts, 152 parts, water, water reducer 9.5 parts;

When strength grade is C35, described granite powder concrete is prepared from by the raw material of following parts by weight: cement 296 parts, breeze 132 parts, granite stone powder 107 parts, 688 parts, sand, rubble 927 parts, 171 parts, water, water reducer 9.9 parts;

When strength grade is C40, described granite powder concrete is prepared from by the raw material of following parts by weight: cement 328 parts, breeze 145 parts, granite stone powder 118 parts, 661 parts, sand, rubble 898 parts, 167 parts, water, water reducer 10.9 parts.

Strength grade of the present invention is not more than the granite powder concrete of C40, wherein: described cement is the ordinary Portland cement of strength grade 42.5 grades; Described breeze is S95 breeze; Described granite stone powder is the granite stone powder that specific surface area is greater than 400; Described Sha Wei II district medium sand; Described rubble is 5-25mm continuous grading granite stones; Described water reducer is polycarboxylate water-reducer.

A kind of concrete preparation method of granite stone powder being not more than C40 for strength grade provided by the present invention, the method comprises the following steps:

(1) raw-material pre-treatment: reject the lump etc. in gelling material;

(2) weigh: weigh each component according to proportioning;

(3) material loading and stirring: add gelling material, sand, rubble, the water accounting for total Water 70% ~ 90%, water reducer successively in stirrer, stir;

(4) added by residue water in concrete and continue to stir, when slump reaches 160-200, prepared by granite powder concrete.

Compared with prior art, the present invention's granite powder concrete of using cement, breeze, granite stone powder and polycarboxylic admixture composite voluntarily to prepare strength grade to be not more than C40 grade.The particle of natural sand and Machine-made Sand is mainly distributed in more than 160 μm, then major part is below 160 μm for the particle of stone flour, and size-grade distribution like this, not only can not hinder the combination of cement and aggregate, fill up the space between aggregate on the contrary, improve the interface structure of starching-gathering materials.Granite stone powder and other raw materials of silicon-aluminum containing matter are first decomposed into aluminosilicate oligomer in various degree in alkali silicate solution, and oligomer generates aluminium silicate glue phase by dehydroxylation polyreaction again, generate by [SiO further ₄] ₄-and [AlO ₄] ₅the interconnective matrix phase with tridimensional network of-tetrahedron, unreacted mineral grain and aggregate are bonded together by matrix phase, thus give material certain mechanical property.Particle diameter in granite stone powder is less than the part of 45 μm as adulterant by the present invention, is used for improving cement components; And part particle diameter in granite stone powder being greater than 45 μm counts in sand, the grain composition of adjustment sand.Under the guidance of concrete material scientific theory, utilize the granite powder concrete that the present invention prepares, be all better than conventional concrete meeting in the early anti-cracking behavior under requirement of strength prerequisite, Anti-Chloride Ion Penetration, anti-carbonation properties etc.Utilizing granite stone powder to prepare concrete not only can to save cement, limestone resource, simultaneously for the raw-material selection of concrete production provides more wide space, respond the calls such as national related resources comprehensive utilization, energy-saving and emission-reduction, there is significant economic benefit and social benefit.

Embodiment

Form is described in further detail foregoing of the present invention again by the following examples, but this should be interpreted as that the scope of the above-mentioned theme of the present invention is only limitted to following embodiment, all technology realized based on foregoing of the present invention all belong to scope of the present invention.

1, test material is as follows:

Cement: PO42.5 ordinary Portland cement

Breeze: S95 breeze

Flyash: II level flyash

Stone flour: granite stone powder (45 μm tail over 38.2%)

Coarse aggregate: 5-25mm continuous grading granite stones, meets the requirement of JGJ52-2006

Fine aggregate: Machine-made Sand, the fineness modulus meeting JGJ52-2006 requirement is the medium sand of 3.1, and silt content is 3%

Admixture: polycarboxylate high performance water-reducing agent composite voluntarily, water-reducing rate is 25%.

The fundamental property of each material is in table 1 ~ table 5:

The physical and mechanical property index of table 1 cement

The performance technologies index of table 2 flyash

The technical indicator of table 3 rubble

Table 4 flyash, breeze and stone flour XRF analysis result (%)

Table 5 granite stone powder technical indicator

2, different cementitious material system concrete test mix-design

Flyash, breeze, stone flour list is utilized to mix or mix replacement cement again, by carrying out test, the indexs such as synthetic study concrete workability, weather resistance, production cost.This test gel material content is respectively 300kg/m ³, 350kg/m ³, 400kg/m ³and 450kg/m ³.Show according to research in the past, granite stone powder activity is lower, and therefore, this problem does not study flyash and stone flour is mixed again.The cementitious material system that this problem adopts is: 1. single fly ash; 2. singly breeze is mixed; 3. singly stone flour is mixed; 4. breeze, stone flour is mixed again, breeze: stone flour=2:1; 5. breeze, stone flour is mixed again, breeze: stone flour=1:1; 6. breeze, stone flour is mixed again, breeze: stone flour=1:2; 7. breeze, flyash is mixed again, breeze: flyash=2:1; 8. breeze, flyash is mixed again, breeze: flyash=1:1; 9. breeze, flyash is mixed again, breeze: flyash=1:2, totally 9 kinds of schemes.Granite stone powder less than 45 μm counts in gelling material, and more than 45 μm count in sand; Test all adopts the sand coarse aggregate ratio of 44%; Admixture dosage accounts for the total amount 2.0% of gelling material; This test controls the slump within the scope of 160 ~ 200mm by adjustment water consumption. concrete testing program and the results are shown in Table 6 and table 7.

Table 6 reference cement mix Design (kg/m ³)

Table 7 mix Design

3, with cementitious material system concrete strength

Each series concrete 28d compression strength value, water-cement ratio and workability of concrete are in table 8.

Table 8

Can obtain drawing a conclusion by analyzing above-mentioned data:

1., in same cementitious material system, when adulterant volume (per-cent) timing, concrete strength increases with the increase of gel material content; When binder total amount one timing, concrete strength reduces with the increase of adulterant volume (per-cent).

2. mix in system at flyash, breeze, granite stone powder list, the concrete strength of breeze system is higher than flyash and granite stone powder system, and the activity demonstrating breeze is thus higher than the activity of flyash and granite stone powder; Compared with flyash system, the concrete strength of stone flour system is slightly high, this is because stone flour system water consumption is few, water-cement ratio is lower than flyash system.

3. mix again in system at granite stone powder and breeze, when gel material content is at 300kg/m3 ~ 400kg/m3, concrete strength improves in the raising of mixing volume in system again with granite stone powder; When gel material content reaches 450kg/m3, concrete strength reduces in the raising of mixing volume in system again with granite stone powder.

4. same mix ratio again under (such as: breeze/stone flour=breeze/flyash=1:2), the concrete strength that breeze and granite stone powder mix system again mixes the concrete strength of system again lower than breeze and flyash.This is because the activity of granite stone powder is lower than the activity of flyash.

5., when gelling material volume is identical, for granite stone powder, the concrete strength singly mixing system will answer lower than granite stone powder and breeze the system of mixing.This is because the activity of granite stone powder is lower than the activity of breeze.

4, the multiple preparation program of different strength concrete

According to " design of common concrete proportioning code " JGJ55-2011 testing laboratory situation, selection standard is poor, and obtain the concrete preparation intensity of each strength grade, standard deviation and trial strength are in table 9.

Table 9 strength grade divides (MPa)

Statistical study is carried out to the concrete strength of 9 cementitious material systems, and linear fit is carried out to gel material content, water-cement ratio and intensity level, obtain regression equation, according to each system gel material content and water-cement ratio and ultimate compression strength relation regression equation, calculate different labels concrete mix.

Table 10C15 granite stone powder concrete mix

Table 11C20 granite stone powder concrete mix

Table 12C25 granite stone powder concrete mix

Table 13C30 granite stone powder concrete mix

Table 14C35 granite stone powder concrete mix

Table 15C40 granite stone powder concrete mix

5, granite stone powder concrete durability experiment

The proportioning of 5.1 endurance tests is determined

The research of granite stone powder concrete durability organizes test as a comparison with construction reference proportioning, as shown in table 3-16:

Table 3-16 concrete construction proportioning

Granite stone powder mix proportion tentatively determines, in table 17 according to construction experience proportioning and " design of common concrete proportioning code " (JGJ55-2011):

Table 3-17 granite stone powder concrete mix

5.2 granite stone powder ion penetration resistance of concretes

The ability of quantitative evaluation concrete opposing chlorine ion binding capacity, can be durability design in Chloride Attack environment and the assessing andpredicting in construction and work-ing life provides basic parameter.Problem adopts the quick chloride ion transport Y-factor method Y of " Standard for test methods of longterm performance and durability of ordinary concrete standard " (GB/T50082-2009) (or claiming RCM method) to evaluate concrete chloride ion permeability.

Table 1828d chloride diffusion coefficient (× 10-12m2/s)

From table 18, along with the rising of concrete strength, chloride diffusion coefficient reduces gradually.Concrete resistance of chloride ion penetration and concrete compactness extent closely related, along with the increase of gel material content, water-cement ratio reduces gradually, the space of concrete grout physical efficiency more evenly, densely between filler aggregate, make chlorion be difficult to diffuse to inside concrete, thus improve concrete resistance of chloride ion penetration.

5.3 granite stone powder agent on crack resistance of concretes are carbonization

Buildings is in life-time service process, and due to effect that is inner or outside, artificial or natural cause, generating material is aging, structural impairment, finally causes structure properties deterioration, depression of bearing force, weather resistance to reduce.Wherein, concrete carbonization is one of major reason causing structure deterioration.Concrete after hydrated cementitious is strong basicity, and high alkalinity environment can make rebar surface produce one deck passive film, and protection reinforcing bar does not weather.But carboniogenesis can make concrete pH value reduce, and rebar surface Damage of Passive Film, in etching medium, reinforcing bar finally corrosion occurs.Steel bar corrosion bulk product expands, and concrete cracking can be caused time serious even to peel off, thus the even security of the weather resistance of structural damage.As can be seen here, concrete carbonization is the prerequisite of reinforcing bar generation corrosion, causes thus

CO in air ₂gas diffuses to concrete surface, and with the alkaline matter generation neutralization reaction of its inside, Formed hydrochlorate and water, thus the process that concrete alkalescence is declined is called concrete carbonization, and also known as doing concrete neutralisation, its chemical equation is:

Ca(OH) ₂+CO ₂=CaCO ₃+H ₂O

Hydrated cementitious can produce a large amount of calcium hydroxide, makes inside concrete be full of saturated aqua calcis, and reinforcing bar produces the passive film (γ-FeOOH) of one deck densification at strong basicity environment lower surface, and protection reinforcing bar does not weather.After concrete generation carbonization, its inner alkalescence reduces, and when pH value is less than 11, passive film is no longer stable.When concrete carbonization reaches (when namely carbonation depth exceedes the protective layer thickness of inside concrete reinforcing bar) after certain depth, rebar passivation film will lose the provide protection to reinforcing bar, and under water and oxygen existent condition, reinforcing bar corrosion will occur.As can be seen here, the inside basicity reduction that concrete carbonization causes is the prerequisite of steel bar corrosion.

1) test method

According to GB/T50082-2009 " normal concrete long-term behaviour and durability test method standard ", make the concrete prism test specimen of 100mm × 100mm × 400mm, each series concrete test specimen proportioning used is in Table 3-16 and table 3-17.This test instrument is the CCB-70W concrete carbonizing test box that Beijing Shuo Zhiyilong Instrument Ltd. produces, and the property indices of this carbonization case meets the regulation of existing industry standard " concrete carbonizing test box " JG/T247.In carbonization case, gas concentration lwevel remains on (20 ± 3) %, and relative humidity controls at (70 ± 5) %, and temperature controls within the scope of (20 ± 2) DEG C.

2) testing sequence

Concrete carbonation test follows these steps to carry out:

1. first the test specimen processed is put into carbonization case, test specimen exposure upwards.Spacing between each test specimen is not less than 50mm.

2., after carbonization case put into by test specimen, carbonization case is sealed.Start gaseous exchange device in case, and be slowly filled with carbonic acid gas, measure the gas concentration lwevel in case.The progressively flow of regulation of carbon dioxide, makes the gas concentration lwevel in case remain on (20 ± 3) %.Take at whole duration of test the measure of drying, make the relative humidity in case control at (70 ± 5) %, temperature controls in the scope of (20 ± 2) DEG C.

3. carbonization test once measures the gas concentration lwevel in case, temperature and humidity every the certain period after starting.Regulate these parameters at any time according to measured gas concentration lwevel, temperature and humidity in test, the silica gel dried should often be changed.

4. when 7d, 14d and 28d have been arrived in carbonization, take out test specimen respectively, broken type measures carbonation depth.Test specimen is by the broken type from one end of the split the law on pressure testing machine.The thickness of each broken type is the half of specimen width, cuts rear paraffin and is sealed by the cut surface of test specimen after broken type, then puts into case continuation carbonization, until next trial period.

5. subsequently the test specimen part of excision gained is brushed away powder remaining on section, then spray the phenolphthalein spirituous solution (spirituous solution contains the distilled water of 20%) that concentration is 1%.About after 30s, every 10mm measurement point Steel Ruler of drawing by original mark measures each point carbonation depth.On the carbonization line of delimitation at measuring point place, be just embedded with coarse aggregate particle, get the depth value of arithmetical av as this point of this particle both sides place carbonation depth.Carbonation depth measurement is accurate to 0.5mm,

Concrete carbonation test result calculates and process meets the following requirements:

1. concrete each test the length of time time average carbonation depth should be calculated as follows:

$\stackrel{\‾}{d_t}=\frac{1}{n}\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{d}_i---(3-3)$

In formula:

---test specimen carbonization t(d) after average carbonation depth (mm), be accurate to 0.1mm;

D _i---the carbonation depth (mm) of each measuring point;

N---measuring point sum.

2. often group using the carbonation depth arithmetical av of 3 test specimen carbonization 28d as this group concrete sample carbonization measured value.

Concrete carbonation test data are in table 19.

Table 19 concrete carbonization depth (mm)

Result shows:

No matter be common coordination in works group or granite powder concrete, its carbonation depth all with carbonization length of time growth and significantly increase;

When carbonization timing in the length of time one, normal concrete and the concrete carbonation depth of granite stone powder all reduce with the raising of concrete strength, this is because gel material content increase can make concrete density improve, and CO2 is not easily to inside concrete diffusion, and its anti-carbonation properties improves;

When carbonization length of time is identical with Intensity Design grade, the concrete carbonation depth of granite stone powder is slightly less than coordination in works concrete, and this is because the alkalescence of granite stone powder hydrated product is higher than pulverized burned coal ash hydration product.

Rule of thumb can obtain, between concrete artificial flash carbonization and natural carbonization, there is following relation:

$X=X_0\sqrt{\frac{\mathrm{ct}}{c_0{t}_0}}$

In formula:

X---the length of time is the concrete carbonization depth of t, mm;

X0---carbonation depth that high-speed carbonation test is surveyed, mm;

C---CO2 volume fraction during natural carbonization in air, %;

C0---the CO2 volume fraction of environment during flash carbonization, %;

T0---flash carbonization length of time, year;

T---natural carbonization length of time, year.

It can thus be appreciated that the degree of depth and the natural carbonization degree of depth of 50 years of artificial flash carbonization 28d are about the same.

Regulation in code for design of concrete structures (GB/T50010-2010): in general environment, design life is the concrete structure of 50 years, and plate, wall, shell concrete cover minimum thickness are 20cm; Beam, post, bar concrete cover minimum thickness are 25cm; When strength grade of concrete is not more than C25, sealer thickness value should increase 5mm; Reinforced concrete foundation should arrange concrete cushion, and in basis, the concrete protective thickness of reinforcing bar should be counted from bed course end face, and should not be less than 40cm.According to the high-speed carbonation test result of this problem, the granite stone powder agent on crack resistance of concrete carbonation properties of different intensity grades can meet code for design of concrete structures corresponding requirements substantially.

5.4 granite powder concrete early anti-cracking behavior energy

Under concrete structure is in free state, shrinkage strain can be produced because of drying, but can not internal stress be caused; But concrete can produce stress because of shrinkage strain under restriction state, and when string stress is greater than the ultimate tensile stress of material, concrete produces cracking.Crack can cause structure impermeability to reduce, and provides passage for the invasion of corrosive medium, finally causes steel bar corrosion and structure deteriorate.Therefore, the research of crack-resistant performance of concrete is particularly important.

1. early stage cracking test research

1) test method

(1) testing apparatus

" normal concrete long-term behaviour and durability test method standard " GB/T50082-2009 defines the early stage cracking test method of concrete, and this test method is applicable to the early anti-cracking behavior energy of test concrete sample under constraint condition.Concrete anticracking testing apparatus is 800mm × 600mm × 100mm planar sheet shaped steel molding jig, and four limits of mould adopt angle steel to be welded at (comprising long side plate and short side plate), and side plate thickness is not less than 5mm, together with mould four limit is bolted on base plate.Be provided with 7 crack-induced devices in mould, crack-induced device uses 50mm × 50mm, 40mm × 40mm angle steel and 5mm × 5mm Plate Welding to form respectively, and is parallel to mould minor face and fixes with base plate.Base plate adopts and is not less than the thick steel plate of 5mm, and does sealing coat at backplate surface laying polyethylene film.Mould as a part of test set, during test and test specimen connect together.

(2) testing sequence

Testing sequence is as follows:

1. testing in temperature is (20 ± 2) DEG C, and relative humidity is carry out in the thermostatic constant wet chamber of (60 ± 5) %;

2. by after in concrete placement to mould, concrete is shakeout, and surface ratio mould frame is slightly high.Concrete mould will be housed put and vibrate on a vibration table, control time of vibration well, prevent from shaking and owe to shake;

3. surperficial with trowel screeding concrete after vibration, and aggregate is not exposed, and make surface plain;

4., after specimen molding 30min, regulate position of fan and wind speed immediately, make 100mm place wind speed directly over surface of test piece center be (5 ± 0.5) m/s.Wind direction should be made to be parallel to surface of test piece and crack-induced device;

5. test period calculates from concrete-agitating adds water, surveys read crack when (24 ± 0.5) h.Fracture length Straight Steel Ruler is measured, and getting two ends, crack slant range is fracture length.When there being two cracks on an edge of a knife, the length of two cracks being added, being converted to a crack;

6. fracture width adopts magnification to be that the crack comprehensive tester of 40 times is measured, and measures the maximum width of every crack;

7. the crack data obtained according to concrete placement 24h measurement calculate the total area of cracks in the average area of cracks of concrete sample, the crack number of unit surface and unit surface;

8. test-results calculates and determines to meet the following requirements:

I. the average area of cracks in every root crack should be calculated as follows:

$a=\frac{1}{2N}\underset{i=1}{\overset{N}{\mathrm{\Σ}}}(w_i\×L_i)$

II. the crack number of unit surface should be calculated as follows:

$b=\frac{N}{A}$

III. the total area of cracks in unit surface should be calculated as follows:

c＝a·b

In formula:

W _i---the maximum width (mm) in i-th crack, is accurate to 0.01mm;

L _i---the length (mm) in i-th crack, is accurate to 1mm;

N---total crack number (root);

A---dull and stereotyped area (m2), is accurate to 2 significant digits;

A---the average area of cracks (mm2/ root) in every root crack, is accurate to 1mm2/ root;

The cracking crack number (root/m2) of b---unit surface, is accurate to 0.1/m2;

C---the total area of cracks (mm2/m2) in unit surface, is accurate to 1mm2/m2.

IV. often organize respectively using the arithmetical av of the average area of cracks of 2 test specimens (the crack number in unit surface or the total area of cracks in unit surface) as the measured value of the average area of cracks of this group test specimen (the crack number in unit surface or the total area of cracks in unit surface).

2) test result analysis

According to the early stage cracking test method of concrete that " normal concrete long-term behaviour and durability test method standard " GB/T50082-2009 specifies, normal concrete and the concrete early anti-cracking behavior of granite stone powder are studied, the results are shown in Table 20:

The concrete per unit cracking area of table 20 (mm2/m2)

As shown in Table 20, the area of cracks of concrete test block increases with the raising of strength grade of concrete; Same levels granite powder concrete early anti-cracking behavior is better than normal concrete; Although granite powder concrete early anti-cracking behavior has certain advantage compared with normal concrete, on the whole, its early anti-cracking behavior is not ideal enough.This is because the early anti-cracking behavior test method of " normal concrete long-term behaviour and durability test method standard " (GB/T50082-2009) defined is mainly applicable to test concrete under constraint condition at the resistance to cleavage of plastic stage, accurately can not reflect the cracking situation that concrete hardening body causes because of drying shrinkage.Result of study in the past also shows, even if concrete early anti-cracking behavior can be poor, as long as maintenance is abundant, the actual resistance to cleavage that later concrete uses also can reach good effect.

6, the determination of granite stone powder concrete production proportioning

Calculate the concrete different preparation program cost of C15, C20, C25, C30, C35 and C40, to determine most economical concrete mix, only calculate concrete material cost.

The prices of raw and semifnished materials are as follows:

Cement: 340 yuan/ton;

Stone flour: 10 yuan/ton;

S95 breeze: 230 yuan/ton;

Sand: 60 yuan/m ³;

Rubble: 70 yuan/m ³;

High performance water reducing agent of polyocarboxy acid: 2000 yuan/ton.

According to the concrete concrete preparation program of different intensity grades granite stone powder in 3.4.1, the concrete raw material cost calculated is as table 21.

Table 21 granite stone powder concrete raw material cost

In conjunction with granite stone powder concrete strength, endurance test and economic analysis results, the best according to JGJ55-2011 Standard Selection different strength concrete prepares scheme as table 22.

The optimum mix of table 22 different strength concrete

Claims (3)

1. the granite powder concrete of a strength grade C40, it is characterized in that: described granite powder concrete is prepared from primarily of gelling material, water, sand, rubble and extra material, described gelling material is cement, breeze and granite stone powder, and described extra material is water reducer;

When strength grade is C40, described granite powder concrete is prepared from by the raw material of following parts by weight: cement 328 parts, breeze 145 parts, granite stone powder 118 parts, 661 parts, sand, rubble 898 parts, 167 parts, water, water reducer 10.9 parts, described breeze is S95 breeze, and described granite stone powder is the granite stone powder that specific surface area is greater than 400, described Sha Wei II district medium sand, described rubble is 5-25mm continuous grading granite stones, and described water reducer is polycarboxylate water-reducer.

2. the granite powder concrete of strength grade C40 according to claim 1, is characterized in that: described cement is the ordinary Portland cement of strength grade 42.5 grades.

3. the concrete preparation method of the granite stone powder of strength grade C40 as claimed in claim 1, the method comprises the following steps:

(1) raw-material pre-treatment: reject the lump in gelling material;

(2) weigh: weigh each component according to proportioning;

(3) material loading and stirring: add gelling material, sand, rubble, the water accounting for total Water 70% ~ 90%, water reducer successively in stirrer, stir;

(4) added by residue water in concrete and continue to stir, when slump reaches 160-200, prepared by granite powder concrete.