A kind of based on freezing process pit shaft anti-crack water-proof agent for concrete
Technical field
The present invention relates to technical field of concrete additives, specifically a kind of based on freezing process pit shaft anti-crack water-proof agent for concrete.
Background technology
Newly-built Coal Mine pit shaft adopts freezing process, main employing double layer reinforced concrete plastic sandwich composite shaft lining structure formation.According to design requirements, inner layer well wall is the main body of permanent wall, plays water shutoff effect, bears whole hydraulic pressure.In recent years, the thickness of surface soil passed along with freezing shaft increases, some special thick alluvium reach more than 800m, after the peripheral freezing wall of freezing shaft wall construction end thaws, under inner layer well wall is subject to the actings in conjunction such as hydrostaticpressure, deadweight, vertical spectra and wall cylinder holding power, in structure, concrete is in multi-dimensional stress state.Showing native aquifer water directly acts on reinforced concrete shaft lining, hydraulic pressure will reach more than 8MPa, inner layer well wall under the long term of high pressure water, in the borehole wall concrete defect damage such as original crack will expand gradually, through cracking, and cause pit shaft percolating water, even there is well shaft destroyed.
Pit shaft concrete construction speed is fast, and concrete strength development wants fast.General to concrete strength demand for development: 8h reaches more than 1.0MPa, 1d be greater than that 35%, 3d of design strength is greater than that 75%, 7d of design strength is greater than design strength 95%.
Pit shaft concrete water-proof requires high, and anti-crack water-proof agent must have the degree of compactness increasing concrete structure and the function reducing concrete shrinkage simultaneously, makes concrete walling reach the object of anti-cracking waterproof, will meet the requirement of concrete strength development simultaneously.
Prepare high-strength concrete in prior art and must use silicon ash, but when silicon ash addition content in concrete brings up to 10% by 5%, the heat-transmission of concrete early water can improve 15% ~ 20%, and the time of concrete cracking can shift to an earlier date about 1/2.Admixture silicon ash can make the viscosity of high-strength concrete very large on the other hand, can bring very large difficulty to construction.
Summary of the invention
For solving above-mentioned prior art Problems existing, the present invention proposes a kind of based on freezing process pit shaft anti-crack water-proof agent for concrete, and to ensure that pit shaft freezing method is constructed, concrete strength development is fast, and concrete does not ftracture, and reaches the object of impervious waterproof.
For achieving the above object, technical scheme of the present invention is:
A kind of based on freezing process pit shaft anti-crack water-proof agent for concrete, each weight percentages of components is: high performance water reducing agent of polyocarboxy acid 3%
~5%, re-dispersible glue powder 1% ~ 4%, aluminum sulfate salt grog 10% ~ 30%
,flint clay 10% ~ 30%
,fluorgypsum 20% ~ 40%, ultrafine slag micro mist 10% ~ 55%.
Described high performance water reducing agent of polyocarboxy acid is the powdered additive with high diminishing, reducing function.
Described re-dispersible glue powder is VAE vinyl acetate-ethylene copolymer re-dispersible glue powder.
The ore of described aluminum sulfate salt grog to be a kind of Tai-Ace S 150 be main component, forms after 750 DEG C ~ 800 DEG C roastings.
Described flint clay be active al2o3 6% ~ 10% high reactivity aluminium flint clay.
Described
ultrafine slag micro mistfor specific surface area is that 900 ~ 1000m2/kg, D50 are greatly about the slag micropowder of 3.0 μm.
Described one based on freezing process pit shaft anti-crack water-proof agent for concrete preparation method is: each component added according to the mass ratio of regulation and grinding is evenly in ball mill.
The present invention is exclusively used in freezing process pit shaft anti-crack water-proof agent for concrete and is applied to anti-cracking waterproof concrete when preparing, and strength grade of concrete is C40 ~ C100, and addition content is 10% ~ 30%.When silicon ash addition content in concrete brings up to 10% by 5%, the heat-transmission of concrete early water can improve 15% ~ 20%, and the time of concrete cracking can shift to an earlier date about 1/2.The present invention does not use silicon ash, breaches the routine that preparation high-strength concrete must use silicon ash! Without one of principal element that silicon ash is minimizing concrete cracking.Admixture silicon ash can make the viscosity of high-strength concrete very large on the other hand, can bring very large difficulty to construction.In the present invention, ultrafine slag micro mist plays early strong enhancement, can reduce the viscosity of high-strength concrete very well.
The water-reducing rate of admixture polycarboxylate high performance water-reducing agent up to 40%, can greatly reduce the reinforcement of concrete water yield, and pore quantity in maturing is reduced; Another effect is reduced, and reduce the contraction of maturing, within 28 days, concrete contraction percentage ratio is not more than 90%.
Re-dispersible glue powder uses more in dry-mixed mortar, and cement and re-dispersible glue powder play the effect of binding agent jointly, and re-dispersible glue powder Main Function plays the cohesive strength improving mortar and matrix, and the drum that rises reducing mortar is peeled off.And the present invention mixes in cement concrete, form irreversible network in cement hydration process, set up a kind of sealing coat to water (film), close the kapillary in cement gel body, blocking hole is to strengthen watertightness.Thisly act on the loss preventing moisture in concrete premature cure process, the effect of interior maintenance can be played.To maturing, the absorption of moisture content can be blocked on the one hand, reduce water-intake rate, prevent the infiltration of moisture content, and improve impermeability; On the other hand certain restraining effect is played to concrete drying shrinkage, namely prevent the contraction in course of hardening, play and reduce effect.
The ore of described aluminum sulfate salt grog to be a kind of Tai-Ace S 150 be main component, forms after 750 DEG C ~ 800 DEG C roastings.After roasting, thus improve its activity, there is very high solvability, and improve the ability of carrying out with cement-hydrate reacting, promptly can interact with gypsum and generate ettringite, thus accelerate and deepen the α-TCP bone cement of cement further.Hydration reaction activity is high, the hydration reaction cycle short (front 7d is comparatively remarkable), and expansion character is stablized, and on early age strength of concrete without obvious impact, later strength has enhancement.Simultaneously because hydration reaction activity is high, the hydration rate of cement can be improved, improve intensity concrete morning.
Flint clay is that in a kind of high alumina high-quality flint clay flint clay, Al2O3 content is 35% ~ 45%, and not containing potassium and sodium, alkali content is extremely low.Some flint clay active aluminum are higher, and active al2o3 is 6% ~ 10%, and the present invention uses active aluminum height flint clay as far as possible.In cement-gypsum gel system, can be more remarkable in hydrated cementitious mid-term (7d--14d) reaction, the hydrated product ettringite that volume increases can be generated.
In the present invention, fluorgypsum is the industrial waste utilizing fluorite to produce hydrofluoric acid, uses after the process of solid fluorine disacidify.A large amount of industrial wastes is utilized, and protection of the environment, economizes on resources.
In the present invention, aluminum sulfate salt grog, flint clay and fluorgypsum belong to ettringite system blended material.Add in cement, the hydrated product ettringite that volume increases can be generated, under the different mechanisms of action of different times, different value, different crystal mineral, these hydrated products can fill, block hardenite pore, change pore structure and hole grating, improve the degree of compactness of hardenite.Macro manifestations concrete produces volumetric expansion, under constraint condition, expansion energy changes into the compressive pre-stress of 0.2 ~ 1.0MPa, suitable stressed condition can be formed in concrete, by continued compensation or cut down concrete contraction, ensure that the clean shrinkage of concrete is less than concrete ultimate extension value all the time in each length of time, make concrete have good resistance to cleavage and anti-permeability performance.
Ultrafine slag micro mist has following characteristics: 1. surface energy is high; 2. microcosmic filling effect; 3. chemically reactive increases.
ultrafine slag micro mistthere are significant fluidisation and reinforcing effect to cement slurry, improve early age strength of concrete, and make paste microstructure densification.
The present invention utilizes the principle of ettringite system blended material and ultra-fine micropowder DSP technology, makes maturing high compaction.Ettringite system blended material, the ultrafine powder with variable grain particle diameter are carried out composite, forms the effect of " gold partnership " with cement, reach the over-superimposed effect of closestpacking.Ultra-fine micropowder, due to its huge surface-area, can store very large surface energy in grinding processes, and the compound action of ettringite system blended material is very remarkable.
Ettringite system blended material can generate a large amount of ettringite, and ultra-fine micropowder can make the unfavorable composition calcium hydroxide in hydrolysis product of cement reduce, and generates more how favourable hydrated calcium silicate.Add the network intertexture that fine xln (the C-S-H gel crystallite formed after aquation) is formed, and have a certain amount of ettringite to be filled with microporosity, concrete structure is reached the most closely fill, most densification, make concrete have the performance do not split and do not ooze.
Relative to prior art, beneficial effect of the present invention is:
1. require to be not more than 200mm relative to the conventional concrete slump, often 40min slump changing value is comparatively large, much larger than 20mm, is unfavorable for construction.The present invention has good concrete mix serviceability, and concrete slump is not more than 20mm at more than 200mm, 40min slump changing value.
2. have higher hour intensity, 8h is greater than 1.5MPa, and 24h is greater than 40% of design strength.
3. the concrete strength rule of development, along with the prolongation in the length of time, concrete strength increasing degree is large.Concrete strength, 8h is greater than 1.0MPa; 24h reaches more than 40% of design strength; 3d reaches more than 80% of design strength; 7d reaches 100% of design strength; 28d reaches more than 120% of design strength; Late strength of concrete sustainable growth, 360d is 28d gain in strength more than 10% comparatively.
4. concrete is fast in low temperature, negative temperature conservation strength development.
Be put into outdoor place without sunshine after concrete formation immediately, surface coverage one deck plastic cloth, carries out maintenance under natural temperature match curing conditions, contrasts with simultaneously shaping and test specimen that is maintenance at the standard conditions.The winter the coldest in Jinan test carry out, and 1d daily temperature is-9 DEG C ~ 2 DEG C; Initial 3d, temperature is lower, and daily minimal tcmperature is between-9 DEG C ~-8 DEG C, and daily maximum temperature is at-1 DEG C ~ 2 DEG C; Initial 7d, daily minimal tcmperature is between-9 DEG C ~-4 DEG C, and daily maximum temperature is at-1 DEG C ~ 4 DEG C; In 28d, daily minimal tcmperature is between-10 DEG C ~-2 DEG C, and daily maximum temperature is at-2 DEG C ~ 7 DEG C.Test-results: concrete strength field curing is compared with the length of time with normal curing, 1d reaches 31.1%, 3d and reaches 74.5%, 7d and reach 75.9%, 28d and reach 87.9%.In fact, field curing 28 intensity has reached more than 100% of design strength.
Maintenance in-10 DEG C of constant temperature refrigerators, compares with normal curing, and 7d intensity reaches and can reach more than 45% of normal curing 7d; Compare with normal concrete, 7d intensity reaches and can reach more than 50% of normal concrete normal curing 28d intensity.
Wellbore hole simulator maintenance and normal curing concrete strength development.After concrete sample is shaping, put into standard curing room maintenance after 1 group of 1d form removal to 28d; Mould is with to put into maintaining box maintenance immediately for 1 group, maintenance processes is as follows: after being warming up to 50 DEG C in constant temperature → 1d after being warming up to 40 DEG C in constant temperature → 1d after being warming up to 30 DEG C in 1d, constant temperature → every d falls 5 DEG C, 10d is down in 0 DEG C → 7d and is down to-15 DEG C, then under-15 DEG C of constant temperature maintenance to 28d.Wellbore hole simulator curing concrete intensity reaches 104% of normal curing, illustrates that practice of construction pit shaft concrete strength does not have disadvantageous effect.
5. have microdilatancy function, have expansion component in formula composition, concrete 7d limited expansion rate in water is 0.15% ~ 0.25%.
6. there is high crack resistance: the cracking test of concrete annulus and dull and stereotyped cracking test confirm, the time of concrete anticracking postpones greatly, and crack quantity reduces simultaneously, and the length in crack shortens, narrowed width, depth shallower.
Concrete annulus cracking test: after concrete formation, moves on to outdoor natural curing after normal curing 24h, and the 1st crack appears in normal concrete 11d, and the concrete mixing anti-crack water-proof agent does not ftracture for 4 months.
Dull and stereotyped cracking test: mix anti-crack water-proof agent concrete and compare with normal concrete, the time that crack occurs boosts 60min, the area that on average splits in crack is decreased to 8.9mm2/ root by 16.9mm2/ root, the cracking crack quantity of concrete unit surface is reduced to 8.3/m2 by 11.1/m2, and the total flaw area in unit surface is decreased to 73.9mm2/m2 by 187.6mm2/m2.
7. having high waterproof ability: Concrete Anti outlet capacity is more than P80, and this is that general concrete waterproofer institute is inaccessiable far away, is one of feature of having of the present invention.
8. have high the resistance of concrete to chloride ion penetration, the chloride diffusion coefficient of preparation C50 is only 35.60 × 10-14m2/s, and concrete permeability is in very low scope.
9. alkalinity is low, not easily alkali-aggregate reaction in concrete occurs, and improves concrete endurance quality.
10. the present invention is exclusively used in freezing process pit shaft anti-crack water-proof agent for concrete and is applied to anti-cracking waterproof concrete when preparing, and strength grade of concrete is C40 ~ C100, and addition content is 10% ~ 30%.When silicon ash addition content in concrete brings up to 10% by 5%, the heat-transmission of concrete early water can improve 15% ~ 20%, and the time of concrete cracking can shift to an earlier date about 1/2.The present invention does not use silicon ash, breaches the routine that preparation high-strength concrete must use silicon ash! Without one of principal element that silicon ash is minimizing concrete cracking.Admixture silicon ash can make the viscosity of high-strength concrete very large on the other hand, can bring very large difficulty to construction.In the present invention, ultrafine slag micro mist plays early strong enhancement, can reduce the viscosity of high-strength concrete very well.
Embodiment
Be described in further detail the present invention below in conjunction with specific embodiment, described embodiment is not intended to limit the present invention content.
Embodiment 1:
A kind of based on freezing process pit shaft anti-crack water-proof agent for concrete, prepare according to the mass ratio of following component:
High performance water reducing agent of polyocarboxy acid 4%;
VAE vinyl acetate-ethylene copolymer re-dispersible glue powder 2%;
Aluminum sulfate salt grog 15%;
Flint clay 15%;
Fluorgypsum 30%;
ultrafine slag micro mist34%;
The preparation method of the present embodiment is, according to the mass ratio of regulation, in ball mill, grinding is evenly.
Preparation C50 concrete, addition content is 12%, and test-results shows:
Serviceability: the slump is 220mm, 60min slump rheological parameters' change with time value is 10mm;
Concrete strength: 8h is 1.5MPa; 24h is 20.6MPa, reaches 41.2% of design strength; 3d is 44.7MPa, reaches 89.4% of design strength; 7d is 51.7MPa, reaches 103.4% of design strength; 28d is 63.0MPa, reaches 126% of design strength; Late strength of concrete sustainable growth, 360d is 28d gain in strength 14% comparatively.
Low-temperature concrete strength development: in outdoor natural temperature maintenance, wherein, 7d temperature is 0 ~ 7 DEG C, and concrete strength is compared with the length of time with normal curing, and 7d reaches 93%, 28d and reaches 96%.Maintenance under low temperature natural temperature condition, concrete strength development is fast, is conducive to the concrete rapid construction of the borehole wall.
Concrete microdilatancy: concrete expansion rate is carried out according to the regulation of " Technical code for application of admixture in concrete " GB50119-2003, in water, 14d limited expansion rate is 0.023%, water 14d+ do empty 28d limited expansion rate still on the occasion of, be 0.008%.Illustrate that concrete shrinkage drop is little after maintenance proceeds to dry empty maintenance in water, is conducive to concrete resistance to cleavage.
The early stage cracking resistance of concrete: dull and stereotyped cracking test result shows, concrete has better early anti-cracking behavior energy.
Water resistant oozes ability: seepage-resistant grade reaches P84.
The resistance of concrete to chloride ion penetration: chloride diffusion coefficient is only 35.60 × 10-14m2/s, concrete permeability is in very low scope.
Embodiment 2
A kind of based on freezing process pit shaft anti-crack water-proof agent for concrete, prepare according to the mass ratio of following component:
High performance water reducing agent of polyocarboxy acid 4%;
VAE vinyl acetate-ethylene copolymer re-dispersible glue powder 4%;
Aluminum sulfate salt grog 15%;
Flint clay 15%;
Fluorgypsum 30%;
ultrafine slag micro mist32%:
The preparation method of the present embodiment is, according to the mass ratio of regulation, in ball mill, grinding is evenly.
Addition content is 12%, preparation C50 concrete, the measurement of test method concrete water demand ratio specified according to " mortar, concrete waterproofer " JC474-2008, and embodiment 1 compares, and result is as follows:
Embodiment 2 concrete water demand ratio is 54.1%, and embodiment 1 concrete water demand ratio is 32.0%.Re-dispersible glue powder has 2% to bring up to 4% being exclusively used in the ratio in freezing process pit shaft anti-crack water-proof agent for concrete, and concrete water demand ratio reduces.But re-dispersible glue powder addition content is excessive, can affect other performance of concrete, re-dispersible glue powder has the optimum mix amount." mortar, concrete waterproofer " JC474-2008 requires concrete water demand ratio otherwise should be greater than 75%, and visible admixture anti-crack water-proof agent of the present invention concrete has very high waterproof ability.
Embodiment 3
A kind of based on freezing process pit shaft anti-crack water-proof agent for concrete, prepare according to the mass ratio of following component:
High performance water reducing agent of polyocarboxy acid 4%;
VAE vinyl acetate-ethylene copolymer re-dispersible glue powder 2%;
Aluminum sulfate salt grog 20%;
Flint clay 20%;
Fluorgypsum 40%;
ultrafine slag micro mist14%;
The preparation method of the present embodiment is, according to the mass ratio of regulation, in ball mill, grinding is evenly.
Embodiment 4
A kind of based on freezing process pit shaft anti-crack water-proof agent for concrete, prepare according to the mass ratio of following component:
High performance water reducing agent of polyocarboxy acid 4%;
VAE vinyl acetate-ethylene copolymer re-dispersible glue powder 2%;
Aluminum sulfate salt grog 10%;
Flint clay 10%;
Fluorgypsum 20%;
ultrafine slag micro mist54%;
The preparation method of the present embodiment is, according to the mass ratio of regulation, in ball mill, grinding is evenly.
Embodiment 4 and embodiment 3 compare:
Concrete strength: embodiment 3, concrete eight h intensity is 1.1MPa; Embodiment 4, concrete eight h intensity is 1.8MPa.Concrete expansion rate: embodiment 3, in water, 14d is 0.021%;
Embodiment 4, in water, 14d is 0.015%.
ultrafine slag micro misthave 14% to bring up to 54% being exclusively used in the ratio in freezing process pit shaft anti-crack water-proof agent for concrete, ettringite system blended material is down to 40% by 80%, and early age strength of concrete significantly improves, and early age strength of concrete development is fast, and concrete expansion decreases.
Test example 1
Utilize embodiment 4 proportioning anti-crack water-proof agent to prepare C50 concrete, mix proportion is: the anti-crack water-proof agent 72kg/m3 of P.O42.5 cement consumption 408kg/m3, medium sand 677kg/m3, rubble 1105kg/m3, water 158kg/m3, embodiment 4.
Be put into outdoor place without sunshine after concrete formation immediately, surface coverage one deck plastic cloth, carries out maintenance under natural temperature match curing conditions, contrasts with simultaneously shaping and test specimen that is maintenance at the standard conditions.The winter the coldest in Jinan test carry out, and 1d daily temperature is-9 DEG C ~ 2 DEG C; Initial 3d, temperature is lower, and daily minimal tcmperature is between-9 DEG C ~-8 DEG C, and daily maximum temperature is at-1 DEG C ~ 2 DEG C; Initial 7d, daily minimal tcmperature is between-9 DEG C ~-4 DEG C, and daily maximum temperature is at-1 DEG C ~ 4 DEG C; In 28d, daily minimal tcmperature is between-10 DEG C ~-2 DEG C, and daily maximum temperature is at-2 DEG C ~ 7 DEG C.Test-results: concrete strength field curing is compared with the length of time with normal curing, 1d reaches 31.1%, 3d and reaches 74.5%, 7d and reach 75.9%, 28d and reach 87.9%.In fact, field curing 28 intensity has reached more than 100% of design strength.
Test example 2
Utilize embodiment 3 proportioning anti-crack water-proof agent to prepare C70 concrete, mix proportion is: the anti-crack water-proof agent 106kg/m3 of P.O52.5 cement 424kg/m3, medium sand 666kg/m3, rubble 1086kg/m3, water 148kg/m3, embodiment 3.
Maintenance in-10 DEG C of constant temperature refrigerators, compares with normal curing, and 7d intensity can reach more than 45% of normal curing 7d; Compare with normal concrete, 7d intensity reaches and can reach more than 50% of normal concrete normal curing 28d intensity.Illustrate that the present invention's strength development under low temperature, negative temperature conservation is fast, practice of construction pit shaft concrete strength meets the requirements completely.
Test example 3
Utilize embodiment 1 proportioning anti-crack water-proof agent to prepare C80 concrete, mix proportion is: the anti-crack water-proof agent 142kg/m3 of P.O52.5 cement 428kg/m3, medium sand 625kg/m3, rubble 1112kg/m3, water 143kg/m3, embodiment 1.
Wellbore hole simulator maintenance and normal curing concrete strength development. after concrete sample is shaping, put into standard curing room maintenance after 1 group of 1d form removal to 28d; Mould is with to put into maintaining box maintenance immediately for 1 group, maintenance processes is as follows: after being warming up to 50 DEG C in constant temperature → 1d after being warming up to 40 DEG C in constant temperature → 1d after being warming up to 30 DEG C in 1d, constant temperature → every d falls 5 DEG C, 10d is down in 0 DEG C → 7d and is down to-15 DEG C, then under-15 DEG C of constant temperature maintenance to 28d.Wellbore hole simulator curing concrete intensity reaches 104% of normal curing, even if under illustrating that the present invention makes concrete be in subzero temperature environment after 10d, concrete strength still can constantly increase, practice of construction pit shaft concrete strength meets the requirements completely.
The present invention obtains successful Application in tens deep frozen shaft engineerings.As dragon solid colliery auxiliary shaft, the total thickness of water-borne sediments is 567.70 meters, depth of freezing 650m.Guo Tun colliery is major and minor, air shaft, and thickness of surface soil is respectively 587.4m, 583.4m and 577.1m, and the depth of freezing is 702m.Yuncheng coal master, auxiliary shaft engineering, through the thick water-borne sediments reaching 534.2m, frozen thickness is at 603m and 625m.