CN111116088B - A special cementing agent for self-curing permeable concrete and its application - Google Patents

Abstract

The invention discloses a special cementing agent for self-curing pervious concrete and application thereof. The cementing agent comprises the following components in parts by weight: 1-5 parts of an internal curing agent, 2-6 parts of a water reducing agent, 10-30 parts of a reinforcing agent and 60-85 parts of an expanding agent; the internal curing agent is selected from one or more of super absorbent resin (SAP) with the grain diameter of 0.075-0.2mm, 0.2-0.3mm, 0.3-0.4mm and 0.4-0.5 mm; the super absorbent resin is any one of starch super absorbent resin, cellulose super absorbent resin and synthetic polymer super absorbent resin. The components of the pervious concrete adopting the special cementing agent have good synergistic effect, the cementing agent absorbs excessive moisture in the production and transportation stage, the water loss condition is weakened before the concrete is hardened, the slurry hanging property of slurry is increased in the transportation process, water is slowly released after the concrete is hardened, the moisture can be provided for the reaction of the expanding agent, the double effects of internal curing are achieved, the shrinkage of the pervious concrete can be reduced, and the cracks of the concrete can be reduced.

Description

A special cementing agent for self-curing permeable concrete and its application

technical field

The invention relates to the technical field of permeable concrete in building materials, in particular to a special cementing agent for self-curing permeable concrete and its application.

Background technique

Permeable concrete has good water permeability, high water storage capacity and good decoration. It is a new type of material worthy of promotion in the construction of "sponge city". It is currently widely used in sidewalks, parking lots and squares. Pervious concrete is a kind of porous lightweight concrete made of aggregate, cementitious material and water. It does not contain fine aggregate. The surface of coarse aggregate is covered with a thin layer of cement paste and bonded to each other to form uniform distribution of pores. honeycomb structure.

There are many problems in the current use of pervious concrete. Pervious concrete has a low water-to-binder ratio (0.25-0.35), which is porous after pouring and paving, and the water is easy to evaporate, resulting in rapid water loss before hardening. If the maintenance is not in place, the surface stones are easy to fall off after hardening, which is prone to drying shrinkage and cracking; insufficient internal moisture to meet hydration will lead to problems such as not increasing the strength in the later stage, or even shrinking; its low water-to-binder ratio and rapid water loss make the expansion agent unable Sufficient hydration reaction, so that it can not play the anti-cracking effect; the fluidity control of permeable concrete in production is much stricter than that of ordinary concrete, if it is slightly thinner, it will segregate; if it is slightly thick, it will not be able to discharge material, and the setting time will be short; the bumps in transportation cause the slurry Body sinks.

Chinese invention patent CN105753405A discloses a self-crystallizing porous gel material and its preparation method and application. In the invention, a gel material with automatic expansion and contraction functions is formed by compounding a micro-expansion agent, a crystallizing agent, and a micro-elastic colloidal particle. Increase the amount of porous fine aggregate to increase the strength of pervious concrete.

Chinese invention patent CN103524085A discloses a high-permeability water-permeable concrete cement and its preparation method and application. The invention adopts furfurone resin, epoxy resin, cement, curing agent and toughening agent to prepare a cement. After use Has good compressive strength and permeability.

The super absorbent substance in the internal curing of ordinary concrete is mixed into the concrete as the internal curing material, considering the reduction of free water after the concrete is hardened, and the water in the internal curing material is released, which is the continuation of the hydration reaction of the cementitious material. Provide moisture to avoid shrinkage cracking.

The internal curing agent is made of super absorbent resin (SAP), which is the most important unit for absorbing and storing water and releasing water later, and can absorb and release water repeatedly. SAP is different from the physical water absorption of thickeners. Its water absorption is in the form of chemical adsorption, and the unreleased water inside it is combined in the form of hydrogen bonds. The water is fixed on the polymer chain and enclosed in the network structure of the polymer. The evaporation of part of the water requires a large amount of energy, and the surface of the SAP particles forms a film, which slows down the drying speed, thereby slowing down the water loss caused by evaporation.

SUMMARY OF THE INVENTION

Aiming at the problems existing in the current permeable concrete, the present invention proposes a special cementing agent for self-curing permeable concrete, which can solve the problem of rapid water loss in the early stage of permeable concrete before hardening, improve the hanging property of aggregates, release water after hardening to achieve self-curing and reduce shrinkage cracking. And to prevent the strength shrinkage problem.

The purpose of the present invention is to overcome the drawbacks of the existing permeable concrete, and propose a method: during the production stage, the binder absorbs and stores excess water, and due to the special structure of SAP, the rapid loss of water is prevented before the concrete is hardened, and the surface stone peeling after hardening is solved. The problem of strength shrinkage; the synergistic effect of the internal curing agent and the reinforcing agent during the transportation process can better improve the hanging performance of the aggregate, without the problem of the slurry sinking to the bottom, which is convenient for the popularization and use of ready-mixed pervious concrete; after hardening, it will be stored The slow release of the water can not only provide water for the expansion agent reaction, but also achieve the dual effect of internal curing, which can reduce shrinkage and reduce cracks; the pore structure of the hardened concrete can be designed through SAP with different particle sizes and different graded stones, SAP After water loss in the concrete, circular holes are formed; for the holes formed by SAP water loss, holes with different diameters can be designed according to the size of SAP, holes with different diameters, especially tiny holes and regular round holes with larger holes And irregular holes are helpful for strength.

The invention provides a kind of special cementing agent for self-curing permeable concrete, comprising the following components, and the mass fractions of each component are as follows:

The inner curing agent is selected from any one or more of superabsorbent resins (SAP) with particle sizes of 0.075-0.2mm, 0.2-0.3mm, 0.3-0.4mm, 0.4-0.5mm; the superabsorbent resins Any one selected from starch-based superabsorbent resin, cellulose-based superabsorbent resin, and synthetic polymer-based superabsorbent resin; the starch-based superabsorbent resin is selected from grafted starch, carboxymethylated starch, phosphate esterified Any one in starch, starch xanthate; Described cellulose superabsorbent resin is selected from any one in grafted cellulose, carboxymethylated cellulose, hydroxypropylated cellulose, xanthated cellulose ; The synthetic polymer superabsorbent resin is selected from any one of polyacrylates, polyacrylonitrile hydrolyzates, vinyl acetate copolymers, and modified polyvinyl alcohols;

The water-reducing agent is a polycarboxylic acid high-performance water-reducing agent powder or a naphthalene-series water-reducing agent powder.

The reinforcing agent is any one or more of silica fume, latex powder and ultrafine limestone powder.

Described expansion agent is any one in ettringite type expansion agent, magnesium oxide type expansion agent and calcium magnesium composite type expansion agent.

A kind of self-curing pervious concrete comprising special cementing agent of the present invention comprises the following components, and the mass fractions of each component are as follows:

The permeable concrete using the special cementing agent of the present invention has a good synergistic effect between the components. The cementing agent absorbs excess water during the production and transportation stage, reduces the water loss before the concrete is hardened, and increases the hanging of the slurry during transportation. After hardening, water is released slowly, which can provide water for the reaction of the expansion agent, and achieve the dual effect of internal curing, which can reduce the shrinkage of permeable concrete and reduce concrete cracks; after hardening, the water in the SAP is completely released, and the pores are formed by themselves. According to the dosage and particle size, the pore structure after hardening can be designed.

Detailed ways

该测试方法适用于下列所有的 实施例。The test method of water evaporation loss rate is to take a certain amount of freshly mixed pervious concrete m ₁ and place it in a drying box at 25 ± 2 °C, and weigh its weight loss for 2 hours as the water evaporation volume m ₂ , and the total weight of permeable concrete m ₃ , water consumption m ₄ , 2h water evaporation rate is

This test method applies to all of the following examples.

Aggregate hanging performance test method: use the sieve weight ratio to quickly evaluate: take 2kg of the prepared freshly mixed pervious concrete into a sieve with an aperture of 2.36mm, put it on a plastic bucket, place it on a vibrating table to vibrate for 60s, and sieve the slurry at the bottom The ratio of the body weight divided by the 2 kg sample size is the sieve weight ratio, and this test method is applicable to all the following examples.

The present invention will be further described in detail below through specific embodiments, but it should not be understood that the scope of the present invention is limited to the following examples.

Example 1: According to the mass parts ratio of 0.2-0.3mm polyacrylonitrile hydrolyzate, polycarboxylate high-performance water reducing agent, silica fume + latex powder, ettringite expansion agent, the ratio of each mass and number = 2:3:20: 75. Mixing and stirring evenly to obtain a self-curing permeable concrete binder; when preparing concrete according to the concrete proportioning in the content of the invention, the admixture of the binder is 10% of the quality of the glue.

Example 2: According to the mass parts ratio of 0.2-0.3mm polyacrylonitrile hydrolyzate, polycarboxylate high-performance water reducing agent, silica fume + latex powder, and ettringite expansion agent, the ratio of each mass and number = 2:3:20: 75. Mixing and stirring evenly to obtain a self-curing permeable concrete binder; when preparing concrete according to the concrete proportioning in the content of the invention, the admixture of the binder is 8% of the amount of the glue material.

Example 3: The ratio of the parts by mass of 0.2-0.3mm modified polyvinyl alcohol, polycarboxylic acid high-performance water reducer, silica fume + latex powder, and ettringite expansion agent = 2:3:20: 75. Mixing and stirring evenly to obtain a self-curing permeable concrete binder; when preparing concrete according to the concrete proportioning in the content of the invention, the admixture of the binder is 12% of the amount of the glue material.

Example 4: According to the mass parts of 0.075-0.2mm+0.3-0.4mm carboxymethyl cellulose, polycarboxylate high-performance water reducer, silica fume + latex powder + ultrafine limestone powder, ettringite expansion agent each mass Part ratio=1:4:20:75; mix and stir evenly to obtain self-curing permeable concrete binder; when preparing concrete according to the concrete proportioning in the content of the invention, the above-mentioned binder dosage is 8% of the amount of glue material.

Example 5: by mass parts 0.075-0.2mm+0.3-0.4mm xanthate cellulose, polycarboxylate high-performance water reducer, silica fume + latex powder + ultrafine limestone powder, ettringite expansion agent by mass Part ratio=1:4:20:75; mix and stir evenly to obtain self-curing permeable concrete binder; when preparing concrete according to the concrete proportioning in the content of the invention, the above-mentioned binder dosage is 10% of the amount of glue material.

Example 6: The ratio of 0.075-0.2mm phosphate esterified starch, polycarboxylate high-performance water reducing agent, silica fume + ultrafine limestone powder, and magnesium oxide expansion agent in parts by mass = 2:5:28: 65; Mix and stir evenly to obtain a self-curing permeable concrete binder; when preparing concrete according to the concrete proportioning in the content of the invention, the admixture of the binder is 11% of the amount of the glue material.

Example 7: Grafted starch, polycarboxylate high-performance water reducer, silica fume + ultrafine limestone powder, and magnesia expansion agent in parts by mass of 0.075-0.2mm ratio by mass = 2:5:28:65 Mixing and stirring evenly to obtain self-curing permeable concrete binder; when preparing concrete according to the concrete proportion in the content of the invention, the admixture of the binder is 9% of the amount of glue material.

Example 8: According to the mass parts ratio of 0.2-0.3mm+0.4-0.5mm vinyl acetate copolymer, polycarboxylate high-performance water reducer, silica fume, calcium-magnesium composite expansion agent=4:6: 15:75; mix and stir evenly to obtain a self-curing permeable concrete binder; when preparing concrete according to the concrete proportioning in the content of the invention, the admixture of the binder is 11% of the amount of the glue material.

Example 9: The ratio of the parts by mass of 0.2-0.3mm+0.4-0.5mm vinyl acetate copolymer, naphthalene-based water reducing agent, silica fume, and calcium-magnesium composite expansion agent=4:6:15:75 Mixing and stirring to obtain a self-curing permeable concrete binder; when preparing concrete according to the concrete proportioning in the invention, the admixture of the binder is 11% of the amount of the glue material.

Comparative Example 1: According to the mass parts of polycarboxylate high-performance water reducing agent, silica fume + latex powder, ettringite expansion agent = 3:20:77, mix and stir evenly to obtain self-curing permeable concrete binder; according to the content of the invention When preparing concrete with concrete proportioning, the admixture of the above-mentioned cementitious agent is 10% of that of the adhesive material.

Comparative Example 2: According to the mass parts of polycarboxylate high-performance water reducing agent and ettringite expansion agent=3:77, the self-curing permeable concrete binder was obtained by mixing and stirring evenly; The amount of binder is 8% of the amount of glue.

Comparative Example 3: When the concrete was prepared according to the concrete proportion in the content of the invention, no cementing agent was added.

With reference to the requirements of CJJ/T135-2009 "Technical Specifications for Permeable Cement Concrete Pavements", the comparison of the concrete performance after adding the special admixture for permeable concrete of the present invention to the control group is carried out, and the test results of various properties of the permeable concrete are shown in the table. 1. In the content of the invention, the mixing ratio of concrete: the mixing ratio of C25 permeable concrete is C:G:W=380:1570:100.

Table 1 Test results of various properties of permeable concrete

The above comparison test shows that: the self-curing permeable concrete after using the special binding agent of the present invention is better than the conventional permeable concrete in all aspects, and the slurry aggregate that can be prepared under the condition of using the binding agent has good bonding performance, no After separation, the water evaporation loss rate in 2h can be controlled at 5.5%-15%, the strength develops normally in the later stage, it can better meet the construction requirements after 2h, and the drying shrinkage at 28d is reduced by 30% or more. Permeable concrete.

Claims (5)

1. The special cementing agent for the self-curing pervious concrete is characterized by comprising the following components in parts by weight:

the internal curing agent is selected from one or more of super absorbent resin (SAP) with the grain diameter of 0.075-0.2mm, 0.2-0.3mm, 0.3-0.4mm and 0.4-0.5 mm; the super absorbent resin is selected from any one of starch super absorbent resin, cellulose super absorbent resin and synthetic polymer super absorbent resin;

the reinforcing agent is the mixture of silica fume and one or two of latex powder and superfine limestone powder.

2. The special cementing agent for self-curing pervious concrete according to claim 1, characterized in that the water reducing agent is polycarboxylic acid high-performance water reducing agent powder or naphthalene water reducing agent powder.

3. The special cementing agent for self-curing pervious concrete according to claim 2, characterized in that the expanding agent is any one of ettringite expanding agents, magnesium oxide expanding agents and calcium-magnesium composite expanding agents.

4. The special cementing agent for self-curing pervious concrete as claimed in claim 3, wherein the starch-based super absorbent resin is selected from any one of grafted starch, carboxymethylated starch, phosphated starch and starch xanthate; the cellulose super absorbent resin is selected from any one of grafted cellulose, carboxymethylated cellulose, hydroxypropylated cellulose and xanthated cellulose; the synthetic polymer super absorbent resin is selected from any one of polyacrylate, polyacrylonitrile hydrolysate, vinyl acetate copolymer and modified polyvinyl alcohol.

5. The application method of the special cementing agent for the self-curing pervious concrete as claimed in any one of claims 1 to 4, characterized in that the cementing agent is applied to the self-curing pervious concrete, and the self-curing pervious concrete containing the cementing agent comprises the following components in parts by weight: