阅读说明：本技术 一种透水混凝土用无机-有机复合粉体增强剂及其应用 (Inorganic-organic composite powder reinforcing agent for pervious concrete and application thereof ) 是由 李辉 杨洁 李准 张毅 于 2021-01-13 设计创作，主要内容包括：本发明涉及一种透水混凝土用无机-有机复合粉体增强剂及其应用,增强剂包括以下组分及重量份含量：硅灰66-71份、可再分散性乳胶粉18-22份、早强剂10-11份、减水剂0.7-0.9份及β-环糊精-碳纳米管复合物0.01-0.05份；应用时,增强剂在透水混凝土的拌合过程中加入,并且增强剂的掺量为水泥质量的4％-6％。与现有技术相比,本发明结合了无机增强和有机增韧的复合改性方法,通过将特定组分按一定比例进行混合,可有效改善水泥胶浆的内聚性能和黏附性能,进而在保持相同孔隙率的前提下改善透水混凝土的抗压强度和抗折强度,对冻融耐久性也具有良好的改善效果。(The invention relates to an inorganic-organic composite powder reinforcing agent for pervious concrete and application thereof, wherein the reinforcing agent comprises the following components in parts by weight: 66-71 parts of silica fume, 18-22 parts of redispersible latex powder, 10-11 parts of early strength agent, 0.7-0.9 part of water reducing agent and 0.01-0.05 part of beta-cyclodextrin-carbon nanotube compound; when the cement admixture is applied, the reinforcing agent is added in the mixing process of the pervious concrete, and the mixing amount of the reinforcing agent is 4-6% of the mass of the cement. Compared with the prior art, the invention combines the inorganic reinforcing and organic toughening composite modification method, and can effectively improve the cohesive property and the adhesion property of the cement mortar by mixing the specific components according to a certain proportion, thereby improving the compressive strength and the flexural strength of the pervious concrete on the premise of keeping the same porosity, and having good improvement effect on the freeze-thaw durability.)

1. The inorganic-organic composite powder reinforcing agent for the pervious concrete is characterized by comprising the following components in parts by weight: 66-71 parts of silica fume, 18-22 parts of redispersible latex powder, 10-11 parts of early strength agent, 0.7-0.9 part of water reducing agent and 0.01-0.05 part of beta-cyclodextrin-carbon nanotube compound.

2. The inorganic-organic composite powder reinforcing agent for pervious concrete according to claim 1, wherein the silica fume has a median particle diameter of 38 to 42 μm.

3. The inorganic-organic composite powder reinforcing agent for water-permeable concrete according to claim 1, wherein the redispersible latex powder is powder-reinforced vinyl acetate-ethylene copolymer.

4. The inorganic-organic composite powder reinforcing agent for pervious concrete according to claim 1, wherein the early strength agent is a formate-based early strength agent.

5. The inorganic-organic composite powder reinforcing agent for pervious concrete according to claim 1, wherein the water reducing agent is a powder type polycarboxylic acid water reducing agent.

6. The inorganic-organic composite powder reinforcing agent for pervious concrete according to claim 1, wherein the β -cyclodextrin-carbon nanotube composite is prepared by the following method: adding beta-cyclodextrin and carbon nano tube into water, filtering after ultrasonic oscillation, and drying.

7. The inorganic-organic composite powder reinforcing agent for water-permeable concrete according to claim 6, wherein the carbon nanotubes comprise one or more of single-walled carbon nanotubes or multi-walled carbon nanotubes, the mass ratio of the beta-cyclodextrin to the carbon nanotubes is (2.5-3.5):1, the temperature of water is 85-95 ℃, the time of ultrasonic oscillation is 3-5h, and the drying temperature is 75-85 ℃.

8. A method for preparing the inorganic-organic composite powder reinforcing agent for pervious concrete according to any one of claims 1 to 7, which comprises: the components are mixed evenly to obtain the reinforcing agent.

9. Use of the inorganic-organic composite powder reinforcing agent according to any one of claims 1 to 7 in pervious concrete.

10. The application of the inorganic-organic composite powder reinforcing agent in pervious concrete according to claim 9, wherein the reinforcing agent is added in the blending process of the pervious concrete, and the mixing amount of the reinforcing agent is 4-6% of the mass of cement.

Technical Field

The invention belongs to the technical field of pervious concrete modifiers, and relates to an inorganic-organic composite powder reinforcing agent for pervious concrete and application thereof.

Background

The pervious concrete pavement has excellent environmental benefit, and the compressive strength of the pervious concrete pavement can be improved to C30 by adopting the reinforcing agent. In order to develop the pervious concrete for medium and heavy load traffic, the mechanical property and the durability of the pervious concrete still have room for improvement. Under the condition of ensuring a certain porosity, three ways are provided for improving the performance of the pervious concrete: firstly, improving the performance of a gelling system; improving the performance of an interface transition region; and increasing the number and area of contact points. The three modes are based on the improvement of the performance of the cement mortar, the performance of the cement mortar is improved by adding the reinforcing agent, the bonding strength between the cement mortar and the aggregate is improved, the area of a contact point is improved, and the method is a main method for improving the strength of the pervious concrete.

At present common concrete reinforcing agent that permeates water is mostly the liquid state, and the mixed liquid has reinforcing effect to a certain extent under the prerequisite of stirring, however, places for a long time and can cause the solid to subside, appears the inhomogeneous phenomenon of reinforcing component distribution. In each use, the reinforcing agent needs to be stirred in most cases, but the stirring cannot ensure uniform mixing of the liquid components, so that the reinforcing effect is unstable. Effective mixing of the reinforcing agent components and effective dispersion thereof in pervious concrete are key to improving the performance of the reinforcing agent. In addition, the pervious concrete is easy to have diseases such as fracture due to insufficient rupture strength, and most reinforcing agents have good reinforcing effect on the compressive strength of the pervious concrete, but have no clear or poor effect on the rupture strength.

Therefore, the reinforcing agent is very important for reinforcing and toughening pervious concrete, and the existing reinforcing agent cannot meet the requirements.

Disclosure of Invention

The invention aims to provide an inorganic-organic composite powder reinforcing agent for pervious concrete and application thereof. The invention comprehensively considers the early and later strength performance, the durability and the environmental benefit of the pervious concrete, uses various powder modified materials and pre-mixes to ensure that the reinforcing agent is uniformly dispersed, thereby obtaining the inorganic-organic composite powder reinforcing agent for reinforcing and toughening the pervious concrete with stable performance and good modification effect, and only adding the reinforcing agent into the mixture during mixing to fully exert the function of the reinforcing agent and improve the performance of the pervious concrete.

The purpose of the invention can be realized by the following technical scheme:

an inorganic-organic composite powder reinforcing agent for pervious concrete comprises the following components in parts by weight: 66-71 parts of silica fume, 18-22 parts of redispersible latex powder, 10-11 parts of early strength agent, 0.7-0.9 part of water reducing agent and 0.01-0.05 part of beta-cyclodextrin-carbon nanotube compound.

Further, the median particle size of the silica fume is 38-42 μm, preferably 40 μm.

Preferably, in the silica fume, SiO₂The content of (A) is more than 95 wt%.

Further, the redispersible latex powder is a powder enhanced vinyl acetate-ethylene copolymer, preferably ETONIS 7550A of Wake chemical Co.

Further, the early strength agent is a formate early strength agent, the content of active ingredients of the formate early strength agent is more than 99.0 wt%, and calcium formate is preferred.

Further, the water reducing agent is a powder type polycarboxylate water reducing agent, and the water reducing rate is preferably 20-30%.

Further, the beta-cyclodextrin-carbon nanotube composite is prepared by the following method: adding beta-cyclodextrin and carbon nano tube into water, filtering after ultrasonic oscillation, and drying.

Further, the carbon nanotubes comprise one or more of single-walled carbon nanotubes or multi-walled carbon nanotubes, the purity is preferably more than 99.5%, the mass ratio of the beta-cyclodextrin to the carbon nanotubes is (2.5-3.5):1, the temperature of the water is 85-95 ℃, the time of ultrasonic oscillation is 3-5h, and the drying temperature is 75-85 ℃.

Preferably, the mass ratio of the beta-cyclodextrin to the carbon nano tube is 3:1, the temperature of the water is 90 ℃, the time of ultrasonic oscillation is 4 hours, and the drying temperature is 80 ℃.

A preparation method of an inorganic-organic composite powder reinforcing agent for pervious concrete comprises the following steps: the components are mixed evenly to obtain the reinforcing agent.

An application of inorganic-organic composite powder reinforcing agent in pervious concrete.

Further, the reinforcing agent is added in the mixing process of the pervious concrete, and the mixing amount of the reinforcing agent is 4-6% of the mass of the cement.

Preferably, the water-cement ratio of the pervious concrete ranges from 0.26 to 0.34; during the blending process, the reinforcing agent is added by a first blending method.

The action mechanism of the invention is as follows:

1. the pores among the cement particles are filled by the small-particle silica fume, so that the cement mortar coating layer is more compact, and the silica fume can be mixed with a cement hydration product Ca (OH)₂The volcanic ash reaction is generated, and the content of hydrated calcium silicate gel is increased;

2. the redispersible latex powder is used for increasing the flexibility of hardened concrete, and the latex powder can form an interconnected reticular membrane after being cured, can glue cement hydration products and has the effects of enhancing and toughening;

3. the water reducing agent and the beta-cyclodextrin-carbon nanotube composite realize good flowing property of cement mortar under a lower water-cement ratio, and the reduction of the water-cement ratio is beneficial to reducing the porosity of the cement mortar and increasing the strength of pervious concrete;

4. the introduction of the redispersible latex powder and the beta-cyclodextrin can cause the delayed coagulation of the pervious concrete, and the addition of the early strength agent can play a role in early strength and ensure the formation of the early strength of the pervious concrete;

5. the carbon nano tube has higher elastic modulus and tensile strength, can better improve the brittleness of cement and enhance the toughness, but has poor dispersibility in water due to the hydrophobic characteristic, and after being mixed with beta-cyclodextrin and ultrasonically compounded, the carbon nano tube increases the affinity of the carbon nano tube with cement paste, increases the cohesive property of the cement paste and can improve the anti-stripping property of pervious concrete.

Compared with the prior art, the invention has the following characteristics:

1) according to the invention, the inorganic reinforcing and organic toughening composite modification method is combined, and the specific components are mixed according to a certain proportion, so that the cohesive property and the adhesion property of the cement mortar can be effectively improved, the compressive strength and the flexural strength of the pervious concrete are improved on the premise of keeping the same porosity, and the freeze-thaw durability is also well improved;

2) the reinforcing agent has good dispersion effect, cannot cause the difference of the performance of the pervious concrete due to uneven dispersion, and has stable performance of each component, and can be taken at any time;

3) different powders respectively play roles in filling, optimizing hydration products, dispersing, tackifying and plasticizing, improving interface bonding and the like, can improve the pore structure and bonding mode of the pervious concrete, and comprehensively improve the mechanical property and durability of the pervious concrete from multiple aspects.

Detailed Description

The present invention will be described in detail with reference to specific examples. The present embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation manner and a specific operation process are given, but the scope of the present invention is not limited to the following embodiments.

The starting materials in examples 1-6 were: SiO in silica fume₂The content is more than 95 wt%, and the median particle size is 40 μm; the redispersible latex powder is ETONIS 7550A of Wake chemical Co; the early strength agent is calcium formate, and the content of the effective component is 99.8 wt%; the water reducing agent is a polycarboxylic acid water reducing agent, and the water reducing rate is 20-30%; the beta-cyclodextrin-carbon nanotube composite is prepared by the following method: adding beta-cyclodextrin and carbon nano tube into water, filtering after ultrasonic oscillation, and drying. Wherein the carbon nanotube is a multi-walled carbon nanotube with a purity of 99.5%, a tube diameter of 20-30nm, a length of 3-12 μm, a specific surface area of 160-220m²(ii)/g; the mass ratio of the beta-cyclodextrin to the carbon nano tube is 3:1, the temperature of water is 90 ℃, the time of ultrasonic oscillation is 4 hours, and the drying temperature is 80 ℃.

Example 1:

as shown in Table 1, the inorganic-organic composite powder reinforcing agent for the pervious concrete comprises the following components in parts by weight: 66 parts of silica fume, 18 parts of redispersible latex powder, 11 parts of early strength agent, 0.7 part of water reducing agent and 0.05 part of beta-cyclodextrin-carbon nanotube compound. The using method comprises the following steps: the reinforcing agent is added in the process of mixing concrete, and the mixing amount of the reinforcing agent is 4 percent of the mass of the cement.

Example 2:

as shown in Table 1, the inorganic-organic composite powder reinforcing agent for the pervious concrete comprises the following components in parts by weight: 71 parts of silica fume, 22 parts of redispersible latex powder, 10 parts of early strength agent, 0.9 part of water reducing agent and 0.01 part of beta-cyclodextrin-carbon nano tube compound. The using method comprises the following steps: the reinforcing agent is added in the process of mixing concrete, and the mixing amount of the reinforcing agent is 6 percent of the mass of the cement.

Example 3:

as shown in Table 1, the inorganic-organic composite powder reinforcing agent for the pervious concrete comprises the following components in parts by weight: 66 parts of silica fume, 22 parts of redispersible latex powder, 11 parts of early strength agent, 0.7 part of water reducing agent and 0.05 part of beta-cyclodextrin-carbon nanotube compound. The using method comprises the following steps: the reinforcing agent is added in the process of mixing concrete, and the mixing amount of the reinforcing agent is 4 percent of the mass of the cement.

Example 4:

as shown in Table 1, the inorganic-organic composite powder reinforcing agent for the pervious concrete comprises the following components in parts by weight: 71 parts of silica fume, 18 parts of redispersible latex powder, 10 parts of early strength agent, 0.9 part of water reducing agent and 0.01 part of beta-cyclodextrin-carbon nano tube compound. The using method comprises the following steps: the reinforcing agent is added in the process of mixing concrete, and the mixing amount of the reinforcing agent is 6 percent of the mass of the cement.

Example 5:

as shown in Table 1, the inorganic-organic composite powder reinforcing agent for the pervious concrete comprises the following components in parts by weight: 71 parts of silica fume, 18 parts of redispersible latex powder, 11 parts of early strength agent, 0.7 part of water reducing agent and 0.01 part of beta-cyclodextrin-carbon nanotube compound. The using method comprises the following steps: the reinforcing agent is added in the process of mixing concrete, and the mixing amount of the reinforcing agent is 6 percent of the mass of the cement.

Example 6:

as shown in Table 1, the inorganic-organic composite powder reinforcing agent for the pervious concrete comprises the following components in parts by weight: 71 parts of silica fume, 18 parts of redispersible latex powder, 11 parts of an early strength agent, 0.9 part of a water reducing agent and 0.05 part of a beta-cyclodextrin-carbon nanotube compound. The using method comprises the following steps: the reinforcing agent is added in the process of mixing concrete, and the mixing amount of the reinforcing agent is 6 percent of the mass of the cement.

The formulations of examples 1-6 are shown in Table 1.

TABLE 1 formula of inorganic-organic composite powder reinforcing agent for water-permeable concrete

The reinforcing agents obtained according to the above examples 1 to 6 were used for the preparation of pervious concrete using basalt broken stones with a single particle size of aggregate 4.75 to 9.5mm and an apparent density of 2.930g/cm³Bulk density of 1.700g/cm³The cement is sea snail brand P.O 42.5 ordinary portland cement, and the designed porosity is 15%. The specific mixing ratio is shown in Table 2. Wherein, the pervious concrete without the reinforcing agent is taken as a comparative example.

TABLE 2 pervious concrete mix proportion

And (3) mixing the pervious concrete by adopting a cement stone-wrapping method. Cubic specimens (100 mm. times.100 mm) and rectangular parallelepiped specimens (100 mm. times.100 mm. times.400 mm) were respectively molded for the characterization of mechanical properties. The mixture was added to the mold in three portions and inserted with a tamper and the surface was vibrated with a plate vibrator for 10 seconds. And covering the surface of the test piece with wet cloth, spraying water periodically after demolding, and covering the test piece with the wet cloth until the test piece is aged. The mechanical property test is carried out according to GB/T50081 standard of test method for mechanical property of common concrete, the anti-freezing test (25 times of rapid freeze-thaw cycles) is carried out according to GB/T50082 standard of test method for long-term property and durability of common concrete, the porosity and effective porosity are tested according to DG/TJ08-2265 standard of application technology for water permeable concrete pavement, and the water permeability coefficient is tested by adopting a variable water head method. The results are shown in Table 3.

TABLE 3 pervious concrete Performance test results

As shown in the test results in Table 3, the compressive strength and the flexural strength of the pervious concrete are effectively improved by the reinforcing agents prepared in the examples 1 to 6, and the improvement ranges are 43 to 87 percent and 17 to 43 percent respectively. According to the performance requirements of CJJT 135 technical Specification for pervious cement concrete pavements, the pervious concrete with the C30 strength grade requires that the 28d compressive strength is more than 30.0MPa, the breaking strength is more than 3.5MPa, the freezing resistance quality loss rate is less than 5%, the water permeability coefficient is more than 0.5mm/s, and the continuous porosity is more than 10%. After the reinforcing agents prepared in the embodiments 1 to 6 are adopted, the strength grade of the pervious concrete reaches C30, the pervious concrete has good water permeability, and particularly, the compressive strength of the pervious concrete can reach 40.3MPa and the flexural strength of the pervious concrete can reach 4.3MPa by adopting the reinforcing agent in the embodiment 6. For reinforcing agents of different groups, due to the difference of the dosage of the tackifying component and the plasticizing component, the working performance of the freshly mixed pervious concrete is different, so that slurry of part of groups is slightly separated, the gap at the bottom of the pervious concrete is slightly blocked, and the permeability coefficient is further reduced.

Example 7:

an inorganic-organic composite powder reinforcing agent for pervious concrete comprises the following components in parts by weight: 66 parts of silica fume, 22 parts of redispersible latex powder, 10 parts of early strength agent, 0.9 part of water reducing agent and 0.01 part of beta-cyclodextrin-carbon nanotube compound.

Wherein the median particle diameter of the silica fume is 42 μm. The redispersible emulsion powder is a powder enhanced vinyl acetate-ethylene copolymer. The early strength agent is formate early strength agent. The water reducing agent is a powder type polycarboxylate water reducing agent.

The beta-cyclodextrin-carbon nanotube composite is prepared by the following method: adding beta-cyclodextrin and carbon nano tube into water, filtering after ultrasonic oscillation, and drying. The carbon nano tube is a single-walled carbon nano tube, the mass ratio of beta-cyclodextrin to the carbon nano tube is 2.5:1, the temperature of water is 95 ℃, the time of ultrasonic oscillation is 3 hours, and the drying temperature is 85 ℃.

The preparation method comprises the following steps: the components are mixed evenly to obtain the reinforcing agent.

When the cement admixture is applied, the reinforcing agent is added in the mixing process of the pervious concrete, and the mixing amount of the reinforcing agent is 4% of the mass of the cement.

Example 8:

an inorganic-organic composite powder reinforcing agent for pervious concrete comprises the following components in parts by weight: 71 parts of silica fume, 18 parts of redispersible latex powder, 11 parts of early strength agent, 0.7 part of water reducing agent and 0.05 part of beta-cyclodextrin-carbon nanotube compound.

Wherein the median particle diameter of the silica fume is 38 μm. The redispersible emulsion powder is a powder enhanced vinyl acetate-ethylene copolymer. The early strength agent is formate early strength agent. The water reducing agent is a powder type polycarboxylate water reducing agent.

The beta-cyclodextrin-carbon nanotube composite is prepared by the following method: adding beta-cyclodextrin and carbon nano tube into water, filtering after ultrasonic oscillation, and drying. The carbon nano tube is a multi-walled carbon nano tube, the mass ratio of beta-cyclodextrin to the carbon nano tube is 3.5:1, the temperature of water is 85 ℃, the time of ultrasonic oscillation is 5 hours, and the drying temperature is 75 ℃.

The preparation method comprises the following steps: the components are mixed evenly to obtain the reinforcing agent.

When the cement admixture is applied, the reinforcing agent is added in the mixing process of the pervious concrete, and the mixing amount of the reinforcing agent is 6% of the mass of the cement.

Example 9:

an inorganic-organic composite powder reinforcing agent for pervious concrete comprises the following components in parts by weight: 68 parts of silica fume, 20 parts of redispersible latex powder, 10.5 parts of early strength agent, 0.8 part of water reducing agent and 0.03 part of beta-cyclodextrin-carbon nanotube compound.

Wherein the median particle diameter of the silica fume is 40 μm. The redispersible emulsion powder is a powder enhanced vinyl acetate-ethylene copolymer. The early strength agent is formate early strength agent. The water reducing agent is a powder type polycarboxylate water reducing agent.

The beta-cyclodextrin-carbon nanotube composite is prepared by the following method: adding beta-cyclodextrin and carbon nano tube into water, filtering after ultrasonic oscillation, and drying. The carbon nano tube comprises a single-walled carbon nano tube and a multi-walled carbon nano tube, the mass ratio of beta-cyclodextrin to the carbon nano tube is 3:1, the temperature of water is 90 ℃, the time of ultrasonic oscillation is 4h, and the drying temperature is 80 ℃.

The preparation method comprises the following steps: the components are mixed evenly to obtain the reinforcing agent.

When the cement admixture is applied, the reinforcing agent is added in the mixing process of the pervious concrete, and the mixing amount of the reinforcing agent is 5% of the mass of the cement.

The embodiments described above are described to facilitate an understanding and use of the invention by those skilled in the art. It will be readily apparent to those skilled in the art that various modifications to these embodiments may be made, and the generic principles described herein may be applied to other embodiments without the use of the inventive faculty. Therefore, the present invention is not limited to the above embodiments, and those skilled in the art should make improvements and modifications within the scope of the present invention based on the disclosure of the present invention.