CN112592109B - Recycled concrete with excellent performance - Google Patents
Recycled concrete with excellent performance Download PDFInfo
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- CN112592109B CN112592109B CN202011351582.XA CN202011351582A CN112592109B CN 112592109 B CN112592109 B CN 112592109B CN 202011351582 A CN202011351582 A CN 202011351582A CN 112592109 B CN112592109 B CN 112592109B
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B20/00—Use of materials as fillers for mortars, concrete or artificial stone according to more than one of groups C04B14/00 - C04B18/00 and characterised by shape or grain distribution; Treatment of materials according to more than one of the groups C04B14/00 - C04B18/00 specially adapted to enhance their filling properties in mortars, concrete or artificial stone; Expanding or defibrillating materials
- C04B20/02—Treatment
- C04B20/023—Chemical treatment
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2201/00—Mortars, concrete or artificial stone characterised by specific physical values
- C04B2201/50—Mortars, concrete or artificial stone characterised by specific physical values for the mechanical strength
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Abstract
The invention provides recycled concrete with excellent performance, which comprises 100 parts of cement, 15-25 parts of recycled coarse aggregate, 20-30 parts of fine aggregate, 10-15 parts of fly ash, 5-15 parts of an early strength water reducing agent and 60-85 parts of water. The recycled concrete provided by the invention has the advantages of small interface damage, high strength, good toughness and excellent mechanical property.
Description
Technical Field
The invention belongs to the field of building materials, and particularly relates to recycled concrete with excellent performance.
Background
With the rapid development of the building industry in China, the use amount of concrete rises year by year, and the aggregate resource with the largest consumption in the preparation of concrete gradually decreases. At the same time, a huge amount of construction waste is generated, and the most important is waste concrete. The waste concrete can be used as a base padding for buildings and roads besides being used as a landfill material, but a large amount of waste concrete is still placed in a garbage site, so that the occupied area is large and the environment is polluted.
The waste concrete contains a large amount of sandstone aggregates. The aggregate formed by crushing, screening, grading and cleaning the waste concrete according to a certain proportion is called recycled aggregate, wherein the aggregate with the particle size of 0.5-5mm is called recycled fine aggregate, and the aggregate with the particle size of 5-40mm is called recycled coarse aggregate. If the sandstone aggregate in the waste concrete can be reasonably utilized under the condition that the mining cost of the natural aggregate is increased year by year, the use of the natural aggregate can be reduced, and the pollution of the waste concrete to the environment can be reduced.
However, due to the existence of a large amount of old mortar in the recycled aggregate, compared with common concrete, the recycled aggregate has certain defects in various mechanical properties, the processing mechanism of the recycled aggregate concrete technology is not perfect at present, and a lot of bottlenecks which need to be broken through are also formed for improving various mechanical property indexes. For example, it is difficult to completely crush the waste concrete in the conventional crushing manner, and the produced aggregate has problems such as rough and uneven surface, containing many micro cracks and old cement mortar, numerous edges and corners, high crushing index, high porosity and water absorption, and the like, so that the performance is inferior to that of natural aggregate, and the durability, frost resistance and other properties of the regenerated concrete are inferior to those of ordinary concrete.
Due to the complexity of the internal structure of the recycled concrete and the diversity and variability of the recycled aggregate, the research on all aspects is not thorough enough, and the technology on the modification aspect is not perfect, so that the application of the recycled aggregate concrete is limited to a certain extent.
The substitution rate, the composition, the age and the water-cement ratio of the recycled aggregate have certain influence on the basic mechanical properties of the recycled concrete, such as tensile strength, splitting tensile strength and the like. Research shows that the basic mechanical property of the recycled concrete is reduced to different degrees compared with that of the common concrete. The students modify the recycled concrete aiming at the reduction of the basic mechanical property and the durability of the recycled concrete compared with the common concrete, and the students add nano materials, rubber, mineral additives, fibers and the like to change the internal structure of the recycled concrete mainly by adding other materials so as to achieve the purpose of changing the performance of a certain aspect. The modification of the nano material is mainly to introduce the nano material into concrete so as to fill pores and cracks in the recycled concrete structure, thereby optimizing the structure at the interface of mortar and aggregate. The addition of rubber into the recycled concrete mainly improves the tension-compression ratio of the recycled concrete, and simultaneously, the rubber is subjected to different modifications and then the recycled concrete is added. After the rubber is added, the tensile-compression ratio of the recycled concrete is larger than that of the common recycled concrete, the brittleness is improved, and the plastic deformation capacity can be improved, but the tensile-compression ratio of the recycled concrete is not greatly influenced by the modification mode of the rubber. Because mineral admixture and fiber are successful precedent in improving the performance of common concrete, the addition of mineral admixture and fiber modification also becomes good choice for the research of modifying recycled concrete. The increase trend of the compressive strength of the recycled concrete after various mineral additives are mixed shows a trend of first decreasing and then increasing. Most fibers can enhance the tensile strength of the recycled concrete, but can slightly reduce the compressive strength, improve the tensile-compression ratio and enhance the toughness of the concrete.
The development of special additives for modifying aggregate, reducing interface damage, optimizing the formula and production process of recycled concrete, improving the performance of the recycled concrete, expanding the application range of the recycled concrete, and being particularly important for treating construction waste and protecting the environment.
Disclosure of Invention
The technical problem is as follows: in order to solve the defects of the prior art, the invention aims to provide a production method of recycled concrete with excellent performance.
The technical scheme is as follows: the invention provides recycled concrete with excellent performance, which comprises 100 parts of cement, 15-25 parts of recycled coarse aggregate, 20-30 parts of fine aggregate, 10-15 parts of fly ash, 5-15 parts of an early strength water reducing agent and 60-85 parts of water.
Preferably, the recycled coarse aggregate is recycled coarse aggregate treated by a recycled aggregate treating agent, and the treatment method comprises the following steps:
(1) stirring the crushed waste concrete at 50-70 ℃ for 20-40min, and washing with water; stirring at 50-70 deg.C for 20-40min, and washing with water to obtain recycled aggregate;
(2) placing the recycled aggregate pretreated in the step (1) into the recycled aggregate treating agent for soaking treatment;
(3) and (4) clearly removing impurities from the soaked recycled aggregate, and drying.
More preferably, the recycled aggregate treating agent comprises the following components in parts by weight: 30-50 parts of polyvinyl alcohol, 5-15 parts of chitosan, 5-15 parts of polysiloxane, 6-10 parts of hydrophilic modified nano silica sol, 10-20 parts of penetrating agent and 60-80 parts of deionized water; the hydrophilic modified nano-silica sol is prepared from the following components in parts by weight: 20-25 parts of nano silicon dioxide, 0.3-0.4 part of vinyl triethoxy siloxane, 0.5-1.0 part of maleic anhydride, 2.0-4.0 parts of acrylic acid, 0.5-1 part of hydroxyethyl acrylate, 0.1-0.3 part of dibenzoyl peroxide, 0.1-0.3 part of polyvinyl alcohol and 65-75 parts of absolute ethyl alcohol.
More preferably, the preparation method of the recycled aggregate treating agent comprises the following steps:
(1) preparing hydrophilic modified nano-silica sol: adding nano silicon dioxide into absolute ethyl alcohol, stirring for 5-10min at 40-50 ℃, adding vinyl triethoxy siloxane, and continuously stirring for reacting for 20-30 min; adding maleic anhydride, acrylic acid and hydroxyethyl acrylate again, continuing stirring for reaction for 10-15min, adding dibenzoyl peroxide, heating to 70-80 ℃ and reacting for 2-3 h; adding polyvinyl alcohol, stirring until the polyvinyl alcohol is completely dissolved, and obtaining hydrophilic modified nano silicon dioxide sol;
(2) dissolving polyvinyl alcohol in deionized water, stirring at 90-95 deg.C for 30-60min, and cooling to obtain polyvinyl alcohol solution;
(3) adding chitosan, polysiloxane and hydrophilic modified nano-silica sol into polyvinyl alcohol solution, and stirring and reacting at 50-60 ℃ for 20-40 min; adding the penetrating agent, and uniformly stirring to obtain the product; the penetrating agent is isobutyl triethoxysilane.
More preferably, the soaking treatment time is 12-24 h; the drying temperature is 50-60 ℃, and the drying time is 10-12 h.
Preferably, the early strength water reducing agent is a random copolymer polymerized from the following monomers: 60-70 parts of unsaturated polyether, 15-25 parts of unsaturated carboxylic acid or unsaturated carboxylate, 3-20 parts of polar unsaturated monomer and 2-5 parts of compounding agent.
More preferably, the unsaturated polyether is prepared from compound a and compound B:
the preparation method comprises the following steps:
adding the compound A and the compound B into a pressure reaction device, adding solvents of cyclohexane, sodium ethoxide and ethylene oxide, and stirring and reacting for 3-6h under the conditions of 160-170 ℃ and 2-3 atm; cooling to 30-40 deg.C, adding glacial acetic acid, and adjusting pH to 6.0-7.5.
More preferably, the unsaturated polyether has a weight average molecular weight of 2000-3000; the unsaturated carboxylic acid is methacrylic acid, maleic acid or succinic acid; the unsaturated carboxylate is an alkali metal salt of methacrylic acid, an alkali metal salt of maleic acid, or an alkali metal salt of succinic acid; the polar unsaturated monomer is sodium methyl propylene sulfonate; the compounding ingredient comprises 10-20% of tertiary carbonate, 1-2% of N-acyl sarcosine, 20-30% of hydroxypropyl starch ether, 4-10% of glycerol and the balance of water.
More preferably, the preparation method of the early strength water reducing agent for recycled concrete comprises the following steps:
(1) preparation of unsaturated polyether: adding the compound A and the compound B into a pressure reaction device, adding solvents cyclohexane, sodium ethoxide and ethylene oxide, and stirring and reacting at 160-170 ℃ under the condition of 2-3 atm; cooling to 30-40 deg.C, adding glacial acetic acid to adjust pH to 6.0-7.5; wherein the structural formulas of the compound A and the compound B are as follows:
(2) adding tertiary carbonate, N-acyl sarcosine, hydroxypropyl starch ether and glycerol into water, and stirring and mixing to obtain a compounding agent;
(3) adding unsaturated polyether, unsaturated carboxylic acid or unsaturated carboxylate and polar unsaturated monomer into a reaction kettle, stirring at constant temperature of 60-80 ℃, adding an initiator, heating to 80-90 ℃, continuing to react for 4-5h, adding a compounding agent, cooling and neutralizing to obtain the polyether polyol.
More preferably, the initiator is ammonium persulfate, and the addition amount of the initiator is 0.3-0.6% of the total amount of reactants.
Has the advantages that: the recycled concrete provided by the invention has the advantages of small interface damage, high strength, good toughness and excellent mechanical property.
The recycled concrete provided by the invention uses the specially-made recycled aggregate treating agent, wherein the hydrophilic modified nano-silica sol and the chitosan can penetrate into smaller gaps in the recycled aggregate to form a bonding layer with the coarse aggregate and the mortar in an interface transition area, so that the stability of the interface transition area is ensured, meanwhile, the hydrophilic modified nano-silica sol and the chitosan can also penetrate into the mortar to be filled with the mortar, the stability of the old mortar structure is ensured, the polyvinyl alcohol and the polysiloxane can penetrate into larger gaps and the surface of the aggregate, the structural stability of aggregate macropores is ensured, and meanwhile, the chitosan forms a stable structure among the water modified nano-silica sol, the polyvinyl alcohol and the polysiloxane, so that the stability of the whole structure of the recycled aggregate is ensured.
The recycled concrete provided by the invention uses the special early water reducing agent for recycled aggregate concrete, so that the setting time of the concrete can be greatly shortened, the early strength is increased, and the water-cement ratio is reduced. The early strength agent is prepared by using special unsaturated polyether, a plurality of side chains are led out from a compound A and a compound B, an unsaturated double bond structure and a phenyl structure are reserved, and the early strength agent has a dense dressing structure, good dispersibility and excellent performance over time.
Detailed Description
The following examples are given to further describe the present invention in detail with reference to specific embodiments. The following examples are intended to illustrate the invention, but not to limit the scope of the invention.
The experimental procedures in the following examples are conventional, except for the specific illustrations. The raw materials and test reagents used in the examples were commercially available products except for those specifically mentioned.
Example 1 preparation of recycled aggregate
The recycled aggregate treating agent comprises the following components in parts by weight: 30 parts of polyvinyl alcohol, 5 parts of chitosan, 15 parts of polysiloxane, 6 parts of hydrophilic modified nano silica sol, 10 parts of penetrating agent and 60 parts of deionized water.
The hydrophilic modified nano-silica sol is prepared from the following components in parts by weight: 20 parts of nano silicon dioxide, 0.3 part of vinyl triethoxy siloxane, 0.5 part of maleic anhydride, 2.0 parts of acrylic acid, 0.5 part of hydroxyethyl acrylate, 0.1 part of dibenzoyl peroxide, 0.1 part of polyvinyl alcohol and 65 parts of absolute ethyl alcohol.
The preparation method of the recycled aggregate treating agent comprises the following steps:
(1) preparing hydrophilic modified nano-silica sol: adding nano silicon dioxide into absolute ethyl alcohol, stirring for 10min at 40 ℃, adding vinyl triethoxy siloxane, and continuously stirring for reacting for 30 min; adding maleic anhydride, acrylic acid and hydroxyethyl acrylate again, continuing stirring for reaction for 15min, adding dibenzoyl peroxide, heating to 70 ℃ and reacting for 3 h; adding polyvinyl alcohol, stirring until the polyvinyl alcohol is completely dissolved, and obtaining hydrophilic modified nano silicon dioxide sol;
(2) dissolving polyvinyl alcohol in deionized water, stirring at 90 deg.C for 60min, and cooling to obtain polyvinyl alcohol solution;
(3) adding chitosan, polysiloxane and hydrophilic modified nano-silica sol into a polyvinyl alcohol solution, and stirring and reacting for 40min at 50 ℃; and adding the penetrant isobutyl triethoxysilane, and uniformly stirring to obtain the finished product.
The method for treating the recycled aggregate by using the recycled aggregate treating agent comprises the following steps:
(1) stirring the crushed waste concrete at 50 ℃ for 40min, and washing with water; stirring at 50 deg.C for 40min, and washing with water to obtain recycled aggregate to be treated;
(2) placing the recycled aggregate pretreated in the step (1) into the recycled aggregate treating agent in the embodiment 1 for soaking treatment for 24 hours;
(3) clearly removing impurities from the recycled aggregate after soaking treatment, and drying; the drying temperature is 50 ℃, and the drying time is 12 h.
Example 2 preparation of recycled aggregate
The recycled aggregate treating agent comprises the following components in parts by weight: 50 parts of polyvinyl alcohol, 15 parts of chitosan, 5 parts of polysiloxane, 10 parts of hydrophilic modified nano silica sol, 20 parts of penetrating agent and 80 parts of deionized water.
The hydrophilic modified nano-silica sol is prepared from the following components in parts by weight: 25 parts of nano silicon dioxide, 0.4 part of vinyl triethoxy siloxane, 1.0 part of maleic anhydride, 4.0 parts of acrylic acid, 1 part of hydroxyethyl acrylate, 0.3 part of dibenzoyl peroxide, 0.3 part of polyvinyl alcohol and 75 parts of absolute ethyl alcohol.
The preparation method of the recycled aggregate treating agent comprises the following steps:
(1) preparing hydrophilic modified nano-silica sol: adding nano silicon dioxide into absolute ethyl alcohol, stirring for 5min at 50 ℃, adding vinyl triethoxy siloxane, and continuously stirring for reacting for 20 min; adding maleic anhydride, acrylic acid and hydroxyethyl acrylate again, continuing stirring for reaction for 10min, adding dibenzoyl peroxide, heating to 80 ℃ and reacting for 2 h; adding polyvinyl alcohol, stirring until the polyvinyl alcohol is completely dissolved, and obtaining hydrophilic modified nano silicon dioxide sol;
(2) dissolving polyvinyl alcohol in deionized water, stirring at 95 ℃ for 30min, and cooling to obtain a polyvinyl alcohol solution;
(3) adding chitosan, polysiloxane and hydrophilic modified nano-silica sol into a polyvinyl alcohol solution, and stirring and reacting for 20min at 60 ℃; and adding the penetrant isobutyl triethoxysilane, and uniformly stirring to obtain the finished product.
The method for treating the recycled aggregate by using the recycled aggregate treating agent comprises the following steps:
(1) stirring the crushed waste concrete at 70 ℃ for 20min, and washing with water; stirring at 70 deg.C for 20min, and washing with water to obtain recycled aggregate to be treated;
(2) placing the recycled aggregate pretreated in the step (1) into the recycled aggregate treating agent in the embodiment 2 for soaking treatment for 24 hours;
(3) clearly removing impurities from the recycled aggregate after soaking treatment, and drying; the drying temperature is 60 ℃, and the drying time is 10 h.
Example 3 preparation of recycled aggregate
The recycled aggregate treating agent comprises the following components in parts by weight: 40 parts of polyvinyl alcohol, 10 parts of chitosan, 10 parts of polysiloxane, 8 parts of hydrophilic modified nano silica sol, 15 parts of penetrating agent and 67 parts of deionized water.
The hydrophilic modified nano-silica sol is prepared from the following components in parts by weight: 22 parts of nano silicon dioxide, 0.35 part of vinyl triethoxy siloxane, 0.8 part of maleic anhydride, 3.0 parts of acrylic acid, 0.8 part of hydroxyethyl acrylate, 0.2 part of dibenzoyl peroxide, 0.2 part of polyvinyl alcohol and 70 parts of absolute ethyl alcohol.
The preparation method of the recycled aggregate treating agent comprises the following steps:
(1) preparing hydrophilic modified nano-silica sol: adding nano silicon dioxide into absolute ethyl alcohol, stirring for 8min at 45 ℃, adding vinyl triethoxy siloxane, and continuously stirring for reacting for 25 min; adding maleic anhydride, acrylic acid and hydroxyethyl acrylate again, continuing stirring for reaction for 13min, adding dibenzoyl peroxide, heating to 75 ℃ and reacting for 2.5 h; adding polyvinyl alcohol, stirring until the polyvinyl alcohol is completely dissolved, and obtaining hydrophilic modified nano silicon dioxide sol;
(2) dissolving polyvinyl alcohol in deionized water, stirring at 92 ℃ for 45min, and cooling to obtain a polyvinyl alcohol solution;
(3) adding chitosan, polysiloxane and hydrophilic modified nano-silica sol into a polyvinyl alcohol solution, and stirring and reacting for 30min at 55 ℃; and adding the penetrant isobutyl triethoxysilane, and stirring uniformly to obtain the finished product.
The method for treating the recycled aggregate by using the recycled aggregate treating agent comprises the following steps:
(1) stirring the crushed waste concrete at 60 ℃ for 30min, and washing with water; stirring at 60 deg.C for 30min, and washing with water to obtain recycled aggregate to be treated;
(2) placing the recycled aggregate pretreated in the step (1) into the recycled aggregate treating agent in the embodiment 3 for soaking treatment for 18 h;
(3) clearly removing impurities from the recycled aggregate after soaking treatment, and drying; the drying temperature is 55 ℃, and the drying time is 101 h.
Example 4
The early strength water reducing agent for the recycled concrete is a random copolymer polymerized by the following monomers: 70 parts of unsaturated polyether, 15 parts of unsaturated carboxylic acid or unsaturated carboxylate, 3 parts of polar unsaturated monomer sodium methyl propylene sulfonate and 2 parts of compounding agent.
Wherein the unsaturated polyether is prepared from a compound A and a compound B in a mass ratio of 1: 2:
the preparation method comprises the following steps:
adding the compound A and the compound B into a pressure reaction device, adding solvents of cyclohexane, sodium ethoxide and ethylene oxide, and stirring and reacting for 6 hours at 160 ℃ and 2 atm; cooling to 30 deg.C, adding glacial acetic acid to adjust pH to 6.0-7.5; its weight average molecular weight was 2000-3000.
Wherein the unsaturated carboxylic acid is methacrylic acid, maleic acid or succinic acid; the unsaturated carboxylic acid salt is an alkali metal salt of methacrylic acid, maleic acid or succinic acid.
Wherein the compounding agent comprises 10% of tertiary carbonate, 2% of N-acyl sarcosine, 30% of hydroxypropyl starch ether, 4% of glycerol and the balance of water.
The preparation method of the early strength water reducing agent comprises the following steps:
(1) preparation of unsaturated polyether: adding the compound A and the compound B into a pressure reaction device, adding solvents of cyclohexane, sodium ethoxide and ethylene oxide, and stirring and reacting for 6 hours at 160 ℃ and 2 atm; cooling to 30 deg.C, adding glacial acetic acid to adjust pH to 6.0-7.5;
(2) adding tertiary carbonate, N-acyl sarcosine, hydroxypropyl starch ether and glycerol into water, and stirring and mixing to obtain a compounding agent;
(3) adding unsaturated polyether, unsaturated carboxylic acid or unsaturated carboxylate and polar unsaturated monomer into a reaction kettle, stirring at constant temperature of 60 ℃, adding initiator ammonium persulfate, wherein the adding amount of the initiator is 0.3 percent of the total amount of reactants, heating to 80 ℃, continuing to react for 5 hours, adding compounding agent, cooling and neutralizing to obtain the product.
Example 5
The early strength water reducing agent for the recycled concrete is a random copolymer formed by polymerizing the following monomers: 60 parts by weight of unsaturated polyether, 25 parts by weight of unsaturated carboxylic acid or unsaturated carboxylate, 20 parts by weight of polar unsaturated monomer sodium methyl propylene sulfonate and 5 parts by weight of compounding agent.
Wherein the unsaturated polyether is prepared from a compound A and a compound B in a mass ratio of 2: 1:
the preparation method comprises the following steps:
adding the compound A and the compound B into a pressure reaction device, adding solvents of cyclohexane, sodium ethoxide and ethylene oxide, and stirring and reacting for 3 hours at the temperature of 170 ℃ and the atm of 3; cooling to 40 deg.C, adding glacial acetic acid to adjust pH to 6.0-7.5; its weight average molecular weight was 2000-3000.
Wherein the unsaturated carboxylic acid is methacrylic acid, maleic acid or succinic acid; the unsaturated carboxylate is an alkali metal salt of methacrylic acid, maleic acid or succinic acid.
Wherein the compounding agent comprises 20% of tertiary carbonate, 1% of N-acyl sarcosine, 20% of hydroxypropyl starch ether, 10% of glycerol and the balance of water.
The preparation method of the early strength water reducing agent comprises the following steps:
(1) preparation of unsaturated polyether: adding the compound A and the compound B into a pressure reaction device, adding solvents of cyclohexane, sodium ethoxide and ethylene oxide, and stirring and reacting for 3 hours at the temperature of 170 ℃ and the atm of 3; cooling to 40 deg.C, adding glacial acetic acid to adjust pH to 6.0-7.5;
(2) adding tertiary carbonate, N-acyl sarcosine, hydroxypropyl starch ether and glycerol into water, and stirring and mixing to obtain a compounding agent;
(3) adding unsaturated polyether, unsaturated carboxylic acid or unsaturated carboxylate and polar unsaturated monomer into a reaction kettle, stirring at constant temperature of 80 ℃, adding initiator ammonium persulfate, wherein the adding amount of the initiator is 0.6 percent of the total amount of reactants, heating to 90 ℃, continuing to react for 4 hours, adding compounding agent, cooling and neutralizing to obtain the product.
Example 6
The early strength water reducing agent for the recycled concrete is a random copolymer polymerized by the following monomers: 65 parts by weight of unsaturated polyether, 20 parts by weight of unsaturated carboxylic acid or unsaturated carboxylate, 12 parts by weight of polar unsaturated monomer sodium methyl propylene sulfonate and 3 parts by weight of compounding agent.
Wherein the unsaturated polyether is prepared from a compound A and a compound B in a mass ratio of 1:
the preparation method comprises the following steps:
adding the compound A and the compound B into a pressure reaction device, adding solvents of cyclohexane, sodium ethoxide and ethylene oxide, and stirring and reacting for 3-6h under the conditions of 160-170 ℃ and 2-3 atm; cooling to 30-40 deg.C, adding glacial acetic acid, and adjusting pH to 6.0-7.5; its weight average molecular weight was 2000-3000.
Wherein the unsaturated carboxylic acid is methacrylic acid, maleic acid or succinic acid; the unsaturated carboxylate is an alkali metal salt of methacrylic acid, maleic acid or succinic acid.
Wherein the compounding agent comprises 15% of tertiary carbonate, 1.5% of N-acyl sarcosine, 25% of hydroxypropyl starch ether, 7% of glycerol and the balance of water.
The preparation method of the early strength water reducing agent comprises the following steps:
(1) preparation of unsaturated polyether: adding the compound A and the compound B into a pressure reaction device, adding solvents of cyclohexane, sodium ethoxide and ethylene oxide, and stirring and reacting for 3-6h under the conditions of 160-170 ℃ and 2-3 atm; cooling to 30-40 deg.C, adding glacial acetic acid to adjust pH to 6.0-7.5;
(2) adding tertiary carbonate, N-acyl sarcosine, hydroxypropyl starch ether and glycerol into water, and stirring and mixing to obtain a compounding agent;
(3) adding unsaturated polyether, unsaturated carboxylic acid or unsaturated carboxylate and polar unsaturated monomer into a reaction kettle, stirring at constant temperature of 70 ℃, adding initiator ammonium persulfate, wherein the adding amount of the initiator is 0.45 percent of the total amount of reactants, heating to 85 ℃, continuing to react for 4.5 hours, adding compounding agent, cooling and neutralizing to obtain the product.
A batch of concrete blocks was prepared using the recycled aggregates of examples 1 to 3 and the early strength water reducing agent of examples 4 to 6, the formulation of which is shown in Table 1, using a conventional method.
TABLE 1
The concrete block is put into clear water and saline (sodium chloride aqueous solution with the mass concentration of 30%) to be maintained for a specified age, the bending strength of the concrete is detected by a concrete pressure detector, and the anti-chloride ion corrosion performance of the concrete block is represented by the bending strength and the corrosion resistance coefficient.
TABLE 2
It will be apparent to those skilled in the art that the above description of specific embodiments of the invention is not intended to limit the application of the invention, and that various equivalents and modifications may be made thereto depending on the circumstances. All such substitutions and modifications are intended to be within the scope of the appended claims without departing from the spirit of the invention.
Claims (7)
1. The recycled concrete with excellent performance is characterized in that: the cement-based early strength water reducing agent comprises 100 parts of cement, 15-25 parts of recycled coarse aggregate, 20-30 parts of fine aggregate, 10-15 parts of fly ash, 5-15 parts of an early strength water reducing agent and 60-85 parts of water;
the recycled coarse aggregate is recycled coarse aggregate treated by a recycled aggregate treating agent, and the treatment method comprises the following steps:
(1) stirring the crushed waste concrete at 50-70 ℃ for 20-40min, and washing with water; stirring at 50-70 deg.C for 20-40min, and washing with water to obtain recycled aggregate;
(2) placing the recycled aggregate pretreated in the step (1) into a recycled aggregate treating agent for soaking treatment;
(3) cleaning the soaked recycled aggregate to remove impurities, and drying;
the recycled aggregate treating agent comprises the following components in parts by weight: 30-50 parts of polyvinyl alcohol, 5-15 parts of chitosan, 5-15 parts of polysiloxane, 6-10 parts of hydrophilic modified nano silica sol, 10-20 parts of penetrating agent and 60-80 parts of deionized water; the hydrophilic modified nano-silica sol is prepared from the following components in parts by weight: 20-25 parts of nano silicon dioxide, 0.3-0.4 part of vinyl triethoxy siloxane, 0.5-1.0 part of maleic anhydride, 2.0-4.0 parts of acrylic acid, 0.5-1 part of hydroxyethyl acrylate, 0.1-0.3 part of dibenzoyl peroxide, 0.1-0.3 part of polyvinyl alcohol and 65-75 parts of absolute ethyl alcohol;
the preparation method of the recycled aggregate treating agent comprises the following steps:
(1) preparing hydrophilic modified nano-silica sol: adding nano silicon dioxide into absolute ethyl alcohol, stirring for 5-10min at 40-50 ℃, adding vinyl triethoxy siloxane, and continuously stirring for reacting for 20-30 min; adding maleic anhydride, acrylic acid and hydroxyethyl acrylate again, continuing stirring for reaction for 10-15min, adding dibenzoyl peroxide, heating to 70-80 ℃ and reacting for 2-3 h; adding polyvinyl alcohol, stirring until the polyvinyl alcohol is completely dissolved, and obtaining hydrophilic modified nano silicon dioxide sol;
(2) dissolving polyvinyl alcohol in deionized water, stirring at 90-95 deg.C for 30-60min, and cooling to obtain polyvinyl alcohol solution;
(3) adding chitosan, polysiloxane and hydrophilic modified nano-silica sol into polyvinyl alcohol solution, and stirring and reacting at 50-60 ℃ for 20-40 min; adding penetrant, and stirring; the penetrating agent is isobutyl triethoxysilane.
2. The recycled concrete with excellent properties as claimed in claim 1, wherein: the soaking time is 12-24 h; the drying temperature is 50-60 ℃, and the drying time is 10-12 h.
3. The recycled concrete with excellent properties as claimed in claim 1, wherein: the early strength water reducing agent is a random copolymer polymerized by the following monomers: 60-70 parts of unsaturated polyether, 15-25 parts of unsaturated carboxylic acid or unsaturated carboxylate, 3-20 parts of polar unsaturated monomer and 2-5 parts of compounding agent.
4. The recycled concrete with excellent properties as claimed in claim 3, wherein: the unsaturated polyether is prepared from a compound A and a compound B:
the preparation method comprises the following steps:
adding the compound A into a pressure reaction device, adding solvents of cyclohexane, sodium ethoxide and ethylene oxide, and stirring and reacting for 3-6h under the conditions of 160-170 ℃ and 2-3 atm; cooling to 30-40 deg.C, adding glacial acetic acid, and adjusting pH to 6.0-7.5.
5. The recycled concrete with excellent properties as claimed in claim 3, wherein: the weight average molecular weight of the unsaturated polyether is 2000-3000; the unsaturated carboxylic acid is methacrylic acid, maleic acid or succinic acid; the unsaturated carboxylate is an alkali metal salt of methacrylic acid, an alkali metal salt of maleic acid, or an alkali metal salt of succinic acid; : the polar unsaturated monomer is sodium methyl propylene sulfonate; the compounding ingredient comprises 10-20% of tertiary carbonate, 1-2% of N-acyl sarcosine, 20-30% of hydroxypropyl starch ether, 4-10% of glycerol and the balance of water.
6. The recycled concrete with excellent properties as claimed in claim 3, wherein: the preparation method of the early strength water reducing agent for the recycled concrete comprises the following steps:
(1) preparation of unsaturated polyether: adding the compound A into a pressure reaction device, adding solvents of cyclohexane, sodium ethoxide and ethylene oxide, and stirring and reacting at 160-170 ℃ and 2-3 atm; cooling to 30-40 deg.C, adding glacial acetic acid to adjust pH to 6.0-7.5; wherein the structural formulas of the compound A and the compound B are as follows:
(2) adding tertiary carbonate, N-acyl sarcosine, hydroxypropyl starch ether and glycerol into water, and stirring and mixing to obtain a compounding agent;
(3) adding unsaturated polyether, unsaturated carboxylic acid or unsaturated carboxylate and polar unsaturated monomer into a reaction kettle, stirring at constant temperature of 60-80 ℃, adding an initiator, heating to 80-90 ℃, continuing to react for 4-5h, adding a compounding agent, cooling and neutralizing to obtain the polyether polyol.
7. The recycled concrete with excellent properties as claimed in claim 6, wherein: the initiator is ammonium persulfate, and the addition amount of the initiator is 0.3-0.6% of the total amount of reactants.
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| CN116874225B (en) * | 2023-09-04 | 2023-11-24 | 湖南凝英新材料科技有限公司 | Glue-reducing type concrete water reducer and preparation method and application thereof |
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