CN109704676B - Anti-permeability recycled concrete and preparation method thereof - Google Patents

Anti-permeability recycled concrete and preparation method thereof Download PDF

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CN109704676B
CN109704676B CN201910050529.7A CN201910050529A CN109704676B CN 109704676 B CN109704676 B CN 109704676B CN 201910050529 A CN201910050529 A CN 201910050529A CN 109704676 B CN109704676 B CN 109704676B
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concrete
coarse aggregate
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water
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CN109704676A (en
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高宜信
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Jiangsu Shengdafei Building Materials Co ltd
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Jiangsu Shengdafei Building Materials Co ltd
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    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02WCLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
    • Y02W30/00Technologies for solid waste management
    • Y02W30/50Reuse, recycling or recovery technologies
    • Y02W30/91Use of waste materials as fillers for mortars or concrete

Abstract

The invention discloses anti-permeability recycled concrete and a preparation method thereof, belonging to the technical field of concrete, and the key point of the technical scheme is that the anti-permeability recycled concrete comprises the following components: cement, coarse aggregate, recycled coarse aggregate, fine aggregate, fly ash, slag powder, a water reducing agent, a composite expanding agent and water; the composite expanding agent comprises, by weight, 25-30 parts of gypsum, 5-10 parts of bauxite, 10-20 parts of calcium oxide, 6-8 parts of sepiolite powder, 6-8 parts of silicon micropowder and 4-6 parts of redispersible latex powder. The invention adopts the recycled coarse aggregate to replace part of coarse aggregate, thereby realizing the reutilization of resources; the composite expanding agent is mixed with the cementing material, the aggregate and the water reducing agent, so that the pores of the concrete can be reduced, the compactness of the concrete is improved, the impermeability of the concrete is improved, and the service life of the concrete is prolonged.

Description

Anti-permeability recycled concrete and preparation method thereof
Technical Field
The invention relates to the technical field of concrete, in particular to impervious recycled concrete and a preparation method thereof.
Background
The common concrete is cement concrete which is prepared by taking cement as a cementing material, taking sand and stone as aggregate, adding an additive according to requirements, then mixing the admixture with water according to a certain proportion and stirring the mixture; because the concrete has rich raw materials, low cost and good plasticity, the yield of the concrete in China tends to increase gradually every year. However, with the development of the modernization of our country, the construction of new cities and the transformation of old cities can gradually increase the amount of concrete wastes, so that the recycling of the concrete wastes is more and more emphasized by people, and the development of recycled concrete is promoted.
The regenerated concrete is prepared by crushing, cleaning and grading waste concrete blocks, mixing the crushed, cleaned and graded waste concrete blocks with a grading agent according to a certain proportion, partially or completely replacing natural aggregates such as sand stones and the like, and adding cement, water and the like. The recycled concrete can be combined into aggregates in the following cases: all aggregates are regenerated aggregates; the coarse aggregate is regenerated aggregate, and the fine aggregate is natural sand; the coarse aggregate is natural gravel or cobble, and the fine aggregate is regenerated aggregate; the reclaimed aggregate replaces part of the coarse aggregate or the fine aggregate.
Compared with natural aggregates, the recycled aggregates have a large amount of fine cracks inside and large porosity, which leads to poor impermeability of concrete made of the recycled aggregates, which reduces the durability of concrete mixtures and affects the service life of the concrete, thus how to improve the impermeability of the concrete is a problem to be solved.
Disclosure of Invention
One of the objects of the present invention is to provide an anti-seepage recycled concrete, which can realize the recycling of resources by using recycled coarse aggregates instead of part of coarse aggregates; the composite expanding agent is mixed with the cementing material, the aggregate and the water reducing agent, so that the pores of the concrete can be reduced, the compactness of the concrete is improved, the impermeability of the concrete is improved, and the service life of the concrete is prolonged.
The technical purpose of the invention is realized by the following technical scheme:
the anti-permeability recycled concrete comprises the following components in parts by weight: 150 parts of cement 130-containing material, 470 parts of coarse aggregate 450-containing material, 420 parts of recycled coarse aggregate 400-containing material, 520 parts of fine aggregate 500-containing material, 60-80 parts of fly ash, 40-60 parts of slag powder, 5-7 parts of water reducing agent, 10-20 parts of composite expanding agent and 140 parts of water 130-containing material;
the composite expanding agent comprises, by weight, 25-30 parts of gypsum, 5-10 parts of bauxite, 10-20 parts of calcium oxide, 6-8 parts of sepiolite powder, 6-8 parts of silicon micropowder and 4-6 parts of redispersible latex powder.
By adopting the technical scheme, the recycled coarse aggregate is adopted to replace part of coarse aggregate, so that the resource can be recycled; the composite expanding agent is mixed with the cementing material, the aggregate and the water reducing agent, so that the pores of the concrete can be reduced, the compactness of the concrete is improved, the impermeability of the concrete is improved, and the service life of the concrete is prolonged.
Further, the composite expanding agent is prepared by adopting the following method: grinding 25-30 parts of gypsum, 5-10 parts of bauxite, 10-20 parts of calcium oxide, 6-8 parts of sepiolite powder and 6-8 parts of silicon micro powder for 20-30min, then adding 4-6 parts of redispersible latex powder, continuing grinding for 30-40min, and screening through a 600-mesh and 800-mesh sieve to obtain the composite expanding agent.
By adopting the technical scheme, the composite expanding agent has the expansion rate matched with concrete, can ensure stable and continuous expansion and fill gaps generated by cement shrinkage, and is also beneficial to improving the binding power of aggregate and cement, further improving the compactness of concrete and improving the impermeability of concrete.
Further, the coarse aggregate is 5-25mm continuous graded natural macadam, and the mud content is less than 1%.
By adopting the technical scheme, the continuously graded natural macadam can be stacked to form a densely filled lap joint framework, so that the porosity of the concrete is reduced, the strength of the concrete is improved, and the impermeability of the concrete is improved.
Further, the recycled coarse aggregate has an apparent density of 2680-3Content of mud<2.0 percent and water absorption of 4.0 to 4.5 percent.
By adopting the technical scheme, the mud content and the water absorption of the recycled coarse aggregate are controlled, and the stability of the performance of the concrete can be improved.
Further, the fine aggregate is sand in zone II, and the apparent density is 2650-2670kg/m3The particle diameter is 0.5-0.25mm, and the mud content<1.0%。
By adopting the technical scheme, the sand in the area II has better gradation, more round and smooth particles, good particle shape and better workability with concrete mixtures, and can be filled into gaps between cement and coarse aggregates, so that the gaps of the concrete are reduced, and the impermeability of the concrete is improved.
Furthermore, the fly ash is class F I fly ash, the fineness of the fly ash (the screen residue of a 45-micron square-hole sieve) is less than 6%, the water demand ratio is less than 95%, the ignition loss is less than 3.5%, and the water content is less than 0.2%.
By adopting the technical scheme, the coal ash contains the volcanic active ingredients, so that the using amount of cement can be reduced, and the hydration heat of the cement can be reduced; by controlling the fineness, the water demand ratio, the ignition loss and the water content of the fly ash, the fly ash can be filled into gaps of concrete, the compactness of the concrete is improved, and the impermeability of the concrete is improved; the fly ash can also improve the fluidity, cohesiveness and water-retaining property of the concrete mixture, so that the concrete mixture is easy to pump and pour for molding, and the time-lapse loss of slump can be reduced.
Further, the slag powder is S95-grade slagPowder with density of 2.8-3.0g/cm3Specific surface area of 420-450m2Kg, the activity index (7d) is 85-90%, the activity index (28d) is 95-100%, the fluidity ratio is not less than 95%, and the water content is 0.2-0.6%.
By adopting the technical scheme, the water consumption can be reduced by adding the slag powder, the consumption of cement is reduced, the hydration heat of the cement is reduced, the slag powder has good chemical activity, and the slag powder can be filled into gaps between the cement and fine aggregates in the concrete after being mixed with water, so that the compactness of the concrete is improved, and the impermeability of the concrete is improved.
Further, the water reducing agent is a polycarboxylic acid high-performance water reducing agent.
By adopting the technical scheme, the polycarboxylic acid high-efficiency water reducing agent belongs to a new generation high-efficiency water reducing agent, can reduce the water consumption, reduce the using amount of cement, has small influence on other performances of concrete, has the effects of adsorption dispersion, wetting and lubrication, and can improve the workability of the concrete.
The second purpose of the invention is to provide a preparation method of the anti-permeability recycled concrete.
The technical purpose of the invention is realized by the following technical scheme:
a preparation method of impervious recycled concrete comprises the following steps:
s1: crushing the waste concrete, and screening to obtain prefabricated recycled coarse aggregate with the particle size of 5-25 mm;
s2: placing the prefabricated recycled coarse aggregate into an acid impregnation liquid for soaking for 2-3h, wherein the weight ratio of the prefabricated recycled coarse aggregate to the acid impregnation liquid is 1: 2; then, soaking the prefabricated recycled coarse aggregate into water for 10-20s, taking out and draining for 4-5h, and then baking for 1-2h at the temperature of 80-90 ℃ to obtain recycled coarse aggregate;
s3: by weight, 150 parts of cement 130-plus, 470 parts of coarse aggregate 450-plus, 420 parts of recycled coarse aggregate 400-plus, 520 parts of fine aggregate 500-plus, 60-80 parts of fly ash, 40-60 parts of slag, 5-7 parts of water reducing agent, 10-20 parts of composite expanding agent and 140 parts of water are uniformly stirred to obtain the anti-seepage recycled concrete.
By adopting the technical scheme, H in the acidic impregnation liquid is obtained after the prefabricated recycled coarse aggregate is soaked in the acidic impregnation liquid+The mortar can react with cement hydrate on the prefabricated recycled coarse aggregate, remove mortar coated outside the prefabricated recycled coarse aggregate, reduce the surface roughness of the prefabricated recycled coarse aggregate, improve the surface performance of the prefabricated recycled coarse aggregate, and improve the workability of concrete mixtures by mixing the treated recycled coarse aggregate with various raw materials.
Further, the acid impregnation liquid is prepared by adopting the following method: adding 10-20 parts by weight of carboxymethyl cellulose into 80-90 parts by weight of 30-40wt% dilute sulfuric acid solution, stirring at the speed of 300-400r/min for 10-15min to prepare suspension, then adding 30-40 parts by weight of nano silicon dioxide and 2-4 parts by weight of dodecyl dimethyl amine oxide into the suspension, and stirring at the speed of 300-400r/min for 10-20min to obtain the acidic impregnation solution.
By adopting the technical scheme, H in the acidic impregnation liquid+The mortar coated outside the prefabricated recycled coarse aggregate can be removed, and the surface roughness of the mortar is reduced; and the carboxymethyl cellulose, the nano-silica and the dodecyl dimethyl amine oxide in the acid impregnation liquid can be filled into fine cracks of the recycled coarse aggregate, so that the porosity and the water absorption of the recycled coarse aggregate are reduced, the strength of the recycled coarse aggregate is improved, and the strength and the impermeability of the concrete can be improved.
In summary, compared with the prior art, the invention has the following beneficial effects:
1. the recycled coarse aggregate is adopted to replace part of coarse aggregate, so that the resource can be recycled; the composite expanding agent is mixed with the cementing material, the aggregate and the water reducing agent, so that the pores of the concrete can be reduced, the compactness of the concrete is improved, the impermeability of the concrete is improved, and the service life of the concrete is prolonged;
2. the composite expanding agent has an expansion rate matched with concrete, can ensure stable and continuous expansion, fills gaps generated by cement shrinkage, and is also helpful for improving the binding power of aggregate and cement, further improving the compactness of the concrete and improving the impermeability of the concrete;
3. h in acidic impregnation solution+The mortar coated outside the prefabricated recycled coarse aggregate can be removed, and the surface roughness of the mortar is reduced; and the carboxymethyl cellulose, the nano-silica and the dodecyl dimethyl amine oxide in the acid impregnation liquid can be filled into fine cracks of the recycled coarse aggregate, so that the porosity and the water absorption of the recycled coarse aggregate are reduced, the strength of the recycled coarse aggregate is improved, and the strength and the impermeability of the concrete can be improved.
Detailed Description
The present invention will be described in further detail below.
Preparation examples of composite expanding agent gypsum in the following preparation examples is selected from industrial grade gypsum powder with a product number of 01 produced by chemical Limited company of Mingtian of Jinan Mingtian; the bauxite is selected from the bauxite with the cargo number 1810 produced by a Longjin mineral processing plant in Lingshou county; the sepiolite powder is sepiolite powder with a product number of 1809 produced by Longjinore product processing factories in Lingshui county; the silicon micropowder is selected from the silicon micropowder with the product number RA-sp1250 produced by Changzhou Roro chemical new material company Limited; the redispersible latex powder is 5010N type redispersible latex powder produced by German Wake.
Preparation example 1 of composite swelling agent: grinding 25kg of gypsum, 5kg of bauxite, 10kg of calcium oxide, 6kg of sepiolite powder and 6kg of silicon micro powder for 20min, adding 4kg of redispersible emulsion powder, continuously grinding for 300min, and sieving by a 600-mesh sieve to obtain the composite expanding agent.
Preparation example 2 of composite swelling agent: grinding 27.5kg of gypsum, 7.5kg of bauxite, 15kg of calcium oxide, 7kg of sepiolite powder and 7kg of silicon micro powder for 25min, adding 5kg of redispersible latex powder, continuously grinding for 35min, and sieving by a 700-mesh sieve to obtain the composite expanding agent.
Preparation example 3 of composite swelling agent: grinding 30kg of gypsum, 10kg of bauxite, 20kg of calcium oxide, 8kg of sepiolite powder and 8kg of silicon micro powder for 30min, adding 6kg of redispersible emulsion powder, continuously grinding for 40min, and sieving by a 800-mesh sieve to obtain the composite expanding agent.
Preparation example 4 of composite swelling agent: the difference between the preparation example and the preparation example 1 of the composite expanding agent is that the redispersible latex powder is not added in the raw materials.
Preparation example of acidic impregnation solution carboxymethyl cellulose in the following preparation examples was selected from carboxymethyl cellulose having a product number of CA-F03, manufactured by domethat new materials ltd, guangzhou; the nano silicon dioxide is selected from nano silicon dioxide with the model number of N20 produced by German wacker; the dodecyl dimethyl amine oxide is the dodecyl dimethyl amine oxide with the model number of OB-02 produced by Guangzhou Honglin chemical technology Co.
Preparation example 1 of acidic immersion liquid: 10kg of carboxymethyl cellulose is added into 80kg of 30 wt% dilute sulfuric acid solution, the mixture is stirred for 10min at the speed of 300r/min to prepare suspension, then 30kg of nano silicon dioxide and 2kg of dodecyl dimethyl amine oxide are added into the suspension, and the mixture is stirred for 10min at the speed of 300r/min to obtain the acidic impregnation liquid.
Preparation example 2 of acidic impregnation solution: adding 15kg of carboxymethyl cellulose into 85kg of 35 wt% dilute sulfuric acid solution, stirring at the speed of 350r/min for 12.5min to prepare suspension, then adding 35kg of nano silicon dioxide and 3kg of dodecyl dimethyl amine oxide into the suspension, and stirring at the speed of 350r/min for 15min to obtain the acidic impregnation liquid.
Preparation example 3 of acidic immersion liquid: adding 20kg of carboxymethyl cellulose into 90kg of 40wt% dilute sulfuric acid solution, stirring for 15min at the speed of 400r/min to prepare suspension, then adding 40kg of nano silicon dioxide and 4kg of dodecyl dimethyl amine oxide into the suspension, and stirring for 20min at the speed of 400r/min to obtain the acidic impregnation solution.
Preparation example 4 of acidic impregnation solution: the difference between this preparation example and preparation example 1 of the acidic impregnation solution is that carboxymethyl cellulose, nano silica, and dodecyldimethylamine oxide were not added to the raw materials.
Preparation example 5 of acidic immersion liquid: this preparation example differs from preparation example 1 of the acidic immersion liquid in that carboxymethyl cellulose and dodecyldimethylamine oxide are not added to the raw materials.
Preparation example 6 of acidic immersion liquid: this preparation example differs from preparation example 1 of the acidic immersion liquid in that dodecyldimethylamine oxide was not added to the starting material.
Third, the polycarboxylic acid water reducer in the following examples is selected from XF-25 type polycarboxylic acid high efficiency water reducer produced by Hivimei building materials science and technology Co., Ltd.
Example 1: the impervious recycled concrete is prepared by adopting the following method:
s1: crushing the waste concrete, and screening to obtain prefabricated recycled coarse aggregate with the particle size of 5-25 mm;
s2: placing the prefabricated recycled coarse aggregate into an acid impregnation liquid for soaking for 2 hours, wherein the weight ratio of the prefabricated recycled coarse aggregate to the acid impregnation liquid is 1: 2; then, soaking the prefabricated recycled coarse aggregate into clear water for 10s, taking out and draining for 4h, and then baking for 1h at the temperature of 80 ℃ to obtain recycled coarse aggregate; the acidic impregnation solution was selected from the acidic impregnation solutions prepared in preparation example 1;
s3: 130kg of P.O.42.5 ordinary portland cement, 450kg of coarse aggregate, 400kg of regenerated coarse aggregate, 500kg of fine aggregate, 60kg of fly ash, 40kg of slag, 5kg of polycarboxylic acid-based high-efficiency water reducing agent, 10kg of composite expanding agent and 130kg of water are uniformly stirred to obtain anti-seepage regenerated concrete; the composite expanding agent is selected from the composite expanding agent prepared in preparation example 1 of the composite expanding agent;
wherein the coarse aggregate is 5-25mm continuous graded natural macadam with mud content<1 percent; the recycled coarse aggregate has an apparent density of 2680kg/m3Content of mud<2.0 percent and the water absorption rate is 4.0 percent; the fine aggregate is medium sand in zone II, and the apparent density is 2650kg/m3The particle diameter is 0.5-0.25mm, and the mud content<1.0 percent; the fly ash is F class I fly ash, the fineness of the fly ash (45 mu m square hole sieve residue)<Water demand ratio of 6%<95% loss on ignition<3.5% water content<0.2 percent; the slag powder is S95 grade slag powder with the density of 2.8g/cm3Specific surface area of 420m2Kg, 85% of activity index (7d), 95% of activity index (28d), more than or equal to 95% of fluidity ratio and 0.2% of water content.
Example 2: the impervious recycled concrete is prepared by adopting the following method:
s1: crushing the waste concrete, and screening to obtain prefabricated recycled coarse aggregate with the particle size of 5-25 mm;
s2: placing the prefabricated recycled coarse aggregate into an acid impregnation liquid for soaking for 2.5 hours, wherein the weight ratio of the prefabricated recycled coarse aggregate to the acid impregnation liquid is 1: 2; then, soaking the prefabricated recycled coarse aggregate into clear water for 15s, taking out and draining for 4.5h, and then baking the prefabricated recycled coarse aggregate at the temperature of 85 ℃ for 1.5 hours to obtain recycled coarse aggregate; the acidic impregnation solution was selected from the acidic impregnation solutions prepared in preparation example 2;
s3: uniformly stirring 140kg of P.O.42.5 ordinary portland cement, 460kg of coarse aggregate, 410kg of recycled coarse aggregate, 510kg of fine aggregate, 70kg of fly ash, 50kg of slag, 6kg of polycarboxylic acid-based high-efficiency water reducing agent, 15kg of composite expanding agent and 135kg of water to obtain anti-seepage recycled concrete; the composite expanding agent is selected from the composite expanding agent prepared in preparation example 2 of the composite expanding agent;
wherein the coarse aggregate is 5-25mm continuous graded natural macadam with mud content<1 percent; the recycled coarse aggregate had an apparent density of 2410kg/m3Content of mud<2.0 percent and the water absorption rate is 4.25 percent; the fine aggregate is medium sand in zone II, and the apparent density is 2660kg/m3The particle diameter is 0.5-0.25mm, and the mud content<1.0 percent; the fly ash is F class I fly ash, the fineness of the fly ash (45 mu m square hole sieve residue)<Water demand ratio of 6%<95% loss on ignition<3.5% water content<0.2 percent; the slag powder is S95 grade slag powder with the density of 2.9g/cm3The specific surface area is 435m2Kg, activity index (7d) 88%, activity index (28d) 98%, fluidity ratio not less than 95%, water content 0.4%.
Example 3: the impervious recycled concrete is prepared by adopting the following method:
s1: crushing the waste concrete, and screening to obtain prefabricated recycled coarse aggregate with the particle size of 5-25 mm;
s2: placing the prefabricated recycled coarse aggregate into an acid impregnation liquid for soaking for 3 hours, wherein the weight ratio of the prefabricated recycled coarse aggregate to the acid impregnation liquid is 1: 2; then, soaking the prefabricated recycled coarse aggregate into clear water for 20s, taking out and draining for 5h, and then baking at the temperature of 90 ℃ for 2h to obtain recycled coarse aggregate; the acidic impregnation solution was selected from the acidic impregnation solutions prepared in preparation example 3;
s3: 150kg of ordinary Portland cement of P.O.42.5, 470kg of coarse aggregate, 420kg of recycled coarse aggregate, 520kg of fine aggregate, 80kg of fly ash, 60kg of slag, 7kg of polycarboxylic acid high-efficiency water reducing agent, 20kg of composite expanding agent and 140kg of water are uniformly stirred to obtain anti-seepage recycled concrete; the composite expanding agent is selected from the composite expanding agent prepared in preparation example 3 of the composite expanding agent;
wherein the coarse aggregate is 5-25mm continuous graded natural macadam with mud content<1 percent; the apparent density of the recycled coarse aggregate is 2420kg/m3Content of mud<2.0 percent and the water absorption rate is 4.5 percent; the fine aggregate is medium sand in zone II, and has an apparent density of 2670kg/m3The particle diameter is 0.5-0.25mm, and the mud content<1.0 percent; the fly ash is F class I fly ash, the fineness of the fly ash (45 mu m square hole sieve residue)<Water demand ratio of 6%<95% loss on ignition<3.5% water content<0.2 percent; the slag powder is S95 grade slag powder with a density of 3.0g/cm3Specific surface area 450m2Kg, activity index (7d) is 90%, activity index (28d) is 100%, fluidity ratio is not less than 95%, and water content is 0.6%.
Comparative example 1: the comparative example differs from example 1 in that no composite swelling agent was added to the raw materials.
Comparative example 2: the comparative example differs from example 1 in that the composite swelling agent in the raw material is selected from the composite swelling agents prepared in preparation example 4 of the preparation examples of the composite swelling agent.
Comparative example 3: the present comparative example differs from example 1 in that the acidic impregnation solution in S2 is selected from the acidic impregnation solutions prepared in preparation example 4 of acidic impregnation solutions.
Comparative example 4: the present comparative example differs from example 1 in that the acidic impregnation solution in S2 is selected from the acidic impregnation solutions prepared in preparation example 5 of acidic impregnation solutions.
Comparative example 5: the present comparative example differs from example 1 in that the acidic impregnation solution in S2 is selected from the acidic impregnation solutions prepared in preparation example 6 of acidic impregnation solutions.
Fifthly, performance test: the properties of the concrete prepared in examples 1 to 3 and comparative examples 1 to 5 were measured as follows, and the results are shown in Table 1.
Resistance to chloride ion permeation: and testing the chloride ion penetration depth of the standard test block according to a rapid chloride ion migration coefficient method in GB/T50082-2009 test method standard for long-term performance and durability of common concrete.
Secondly, water penetration resistance, namely testing the water penetration depth of the standard test block according to a step-by-step pressurization method in GB/T50082-2009 Standard test method for the long-term performance and durability of common concrete.
③ anti-seepage pressure: and testing the seepage pressure resistance of the standard test block according to GB/T50082-2009 Standard test method for the long-term performance and durability of the common concrete.
Compression strength: and (3) manufacturing a standard test block according to GB/T50081-2016 standard of mechanical property test method for common concrete, and measuring the compressive strength of the standard test block maintained for 1d, 7d and 28 d.
Early crack resistance: and (3) making a standard test block according to GB/T50081-2016 (Standard test method for mechanical properties of common concrete), and measuring after concrete pouring for 24 hours to obtain the number of cracks in a unit area and the total crack area in the unit area.
TABLE 1
The data show that the concrete prepared by the invention has good water seepage resistance and salt seepage resistance, excellent seepage pressure resistance and early cracking resistance, and better compressive strength.
Compared with the concrete prepared in the example 1, the concrete prepared in the comparative example 1 has obviously reduced water seepage resistance, salt seepage resistance, seepage pressure resistance, compressive strength and early crack resistance because the composite expanding agent is not added in the comparative example 1, which shows that the composite expanding agent can obviously improve the seepage resistance, crack resistance and compressive strength of the concrete.
Compared with the concrete prepared in the example 1, the concrete prepared in the comparative example 2 has obviously reduced water seepage resistance, salt seepage resistance, seepage pressure resistance, compressive strength and early cracking resistance because the redispersible latex powder is not added into the composite expanding agent in the comparative example 2, which shows that the redispersible latex powder in the composite expanding agent is helpful for improving the seepage resistance, the cracking resistance and the compressive strength of the concrete.
The acid impregnation liquid in the comparative example 3 does not contain carboxymethyl cellulose, nano silica and dodecyl dimethyl amine oxide, and compared with the example 1, the concrete in the comparative example 3 has obviously reduced water seepage resistance, salt seepage resistance, seepage pressure resistance and compressive strength, which shows that when the prefabricated recycled coarse aggregate is treated, the carboxymethyl cellulose, the nano silica and the dodecyl dimethyl amine oxide are filled into the pores of the recycled coarse aggregate, so that the compactness and the strength of the recycled coarse aggregate are improved, and the anti-permeability performance and the compressive strength of the concrete are improved.
The acid impregnation liquid in the comparative example 4 does not contain carboxymethyl cellulose and dodecyl dimethyl amine oxide, compared with the example 1, the water seepage resistance, salt seepage resistance, seepage pressure resistance and compressive strength of the concrete in the comparative example 4 are obviously reduced, compared with the comparative example 3, the water seepage resistance, salt seepage resistance, seepage pressure resistance and compressive strength of the concrete in the comparative example 4 are improved to a small extent, which shows that the nano silica in the acid impregnation liquid can improve the strength and compactness of the recycled coarse aggregate, but if only the nano silica is contained, the nano silica has poor dispersibility in dilute sulfuric acid and has poor filling effect on the recycled coarse aggregate.
The acid impregnation liquid in the comparative example 5 does not contain dodecyl dimethyl amine oxide, and compared with the acid impregnation liquid in the comparative example 4, the concrete in the comparative example 5 has improved water seepage resistance, salt seepage resistance, seepage pressure resistance and compressive strength, which shows that carboxymethyl cellulose can improve the dispersibility of nano silicon dioxide, improve the suspension property of the nano silicon dioxide, enable the nano silicon dioxide to be filled into the recycled coarse aggregate, and improve the strength and compactness of the recycled coarse aggregate; comparative example 5 shows that the water permeation resistance, salt permeation resistance, permeation pressure resistance and compressive strength are still lower than those of the examples, and the dodecyl dimethyl amine oxide can promote the dispersion of carboxymethyl cellulose, and the dodecyl dimethyl amine oxide and the carboxymethyl cellulose have a synergistic effect when being used together, so that the water permeation resistance and compressive strength of concrete can be obviously improved.
The present embodiment is only for explaining the present invention, and it is not limited to the present invention, and those skilled in the art can make modifications of the present embodiment without inventive contribution as needed after reading the present specification, but all of them are protected by patent law within the scope of the claims of the present invention.

Claims (9)

1. An impervious recycled concrete, which is characterized in that: the paint comprises the following components in parts by weight:
150 parts of cement 130-containing material, 470 parts of coarse aggregate 450-containing material, 420 parts of recycled coarse aggregate 400-containing material, 520 parts of fine aggregate 500-containing material, 60-80 parts of fly ash, 40-60 parts of slag powder, 5-7 parts of water reducing agent, 10-20 parts of composite expanding agent and 140 parts of water 130-containing material;
the composite expanding agent comprises, by weight, 25-30 parts of gypsum, 5-10 parts of bauxite, 10-20 parts of calcium oxide, 6-8 parts of sepiolite powder, 6-8 parts of silica micropowder and 4-6 parts of redispersible latex powder;
the composite expanding agent is prepared by the following method: grinding 25-30 parts of gypsum, 5-10 parts of bauxite, 10-20 parts of calcium oxide, 6-8 parts of sepiolite powder and 6-8 parts of silicon micro powder for 20-30min, then adding 4-6 parts of redispersible latex powder, continuing grinding for 30-40min, and screening through a 600-mesh and 800-mesh sieve to obtain the composite expanding agent.
2. The impervious recycled concrete of claim 1, wherein: the coarse aggregate is 5-25mm continuous graded natural macadam, and the mud content is less than 1%.
3. The impervious recycled concrete of claim 1, wherein: the regenerated coarse boneThe apparent density of the material is 2680-3Content of mud<2.0 percent and water absorption of 4.0 to 4.5 percent.
4. The impervious recycled concrete of claim 1, wherein: the fine aggregate is sand in zone II, and the apparent density is 2650-2670kg/m3The particle diameter is 0.5-0.25mm, and the mud content<1.0%。
5. The impervious recycled concrete of claim 1, wherein: the fly ash is F class I fly ash, the fineness of the fly ash left by a 45-micron square-hole sieve is less than 6%, the water demand ratio is less than 95%, the ignition loss is less than 3.5%, and the water content is less than 0.2%.
6. The impervious recycled concrete of claim 1, wherein: the slag powder is S95-grade slag powder, and the density is 2.8-3.0g/cm3Specific surface area of 420-450m2The activity index of 7 days is 85-90%, the activity index of 28 days is 95-100%, the fluidity ratio is more than or equal to 95%, and the water content is 0.2-0.6%.
7. The impervious recycled concrete of claim 1, wherein: the water reducing agent is a polycarboxylic acid high-performance water reducing agent.
8. The method of preparing an impervious recycled concrete according to any one of claims 1 to 7, wherein: the method comprises the following steps:
s1: crushing the waste concrete, and screening to obtain prefabricated recycled coarse aggregate with the particle size of 5-25 mm;
s2: placing the prefabricated recycled coarse aggregate into an acid impregnation liquid for soaking for 2-3h, wherein the weight ratio of the prefabricated recycled coarse aggregate to the acid impregnation liquid is 1: 2; then, soaking the prefabricated recycled coarse aggregate into water for 10-20s, taking out and draining for 4-5h, and then baking for 1-2h at the temperature of 80-90 ℃ to obtain recycled coarse aggregate;
s3: by weight, 150 parts of cement 130-plus, 470 parts of coarse aggregate 450-plus, 420 parts of recycled coarse aggregate 400-plus, 520 parts of fine aggregate 500-plus, 60-80 parts of fly ash, 40-60 parts of slag, 5-7 parts of water reducing agent, 10-20 parts of composite expanding agent and 140 parts of water are uniformly stirred to obtain the anti-seepage recycled concrete.
9. The method of claim 8, wherein the concrete further comprises: the acid impregnation liquid is prepared by adopting the following method: adding 10-20 parts by weight of carboxymethyl cellulose into 80-90 parts by weight of 30-40wt% dilute sulfuric acid solution, stirring at the speed of 300-400r/min for 10-15min to prepare suspension, then adding 30-40 parts by weight of nano silicon dioxide and 2-4 parts by weight of dodecyl dimethyl amine oxide into the suspension, and stirring at the speed of 300-400r/min for 10-20min to obtain the acidic impregnation solution.
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