阅读说明：本技术 用于沥青混合料的水泥基再生骨料涂层方法 (Cement-based recycled aggregate coating method for asphalt mixture ) 是由 王杰 徐剑 秦永春 黄颂昌 于 2021-11-19 设计创作，主要内容包括：本发明公开了一种用于沥青混合料的水泥基再生骨料涂层方法。首先在再生骨料表面涂覆矿渣硅酸盐水泥浆体以增强再生骨料的强度,然后涂覆丙烯酸基防水涂料,降低再生骨料孔隙,以减少再生骨料其对水/沥青的吸收,提高再生骨料与沥青之间的界面黏结强度,最终全面提升基于水泥基再生骨料的沥青混合料的路用性能。(The invention discloses a coating method of cement-based recycled aggregate for an asphalt mixture. Firstly, coating slag silicate cement slurry on the surface of the recycled aggregate to enhance the strength of the recycled aggregate, then coating acrylic-based waterproof coating to reduce the pores of the recycled aggregate, so as to reduce the absorption of the recycled aggregate to water/asphalt, improve the interface bonding strength between the recycled aggregate and asphalt, and finally comprehensively improve the pavement performance of the asphalt mixture based on the cement-based recycled aggregate.)

1. A method for coating cement-based recycled aggregate for asphalt mixture is characterized by comprising the following steps:

providing concrete particles with a preset particle size as cement-based recycled aggregate A;

coating slag silicate cement slurry on the surface of the recycled aggregate A;

carrying out hydration reaction on the recycled aggregate A wrapped with the slag silicate cement paste to obtain recycled aggregate A1;

providing a mixed solution B1 prepared by mixing acrylic acid-based waterproof paint and water;

coating the mixed solution B1 on the surface of the recycled aggregate A1 to obtain recycled aggregate A2;

providing a mixed solution B2 prepared by mixing acrylic acid-based waterproof paint and water;

mixing the mixed solution B2 with the recycled aggregate A2 and drying.

2. The method of claim 1,

2 parts by mass of slag portland cement is mixed with 1 part by mass of water to prepare slag portland cement paste.

3. The method according to claim 1 or 2,

the mixing and stirring time of the recycled aggregate A and the slag silicate cement slurry is 1-3 minutes, and the mixture is placed for 20-28 hours after stirring is completed; the mass of the slag silicate cement paste is 1-3% of the mass of the recycled aggregate A.

4. The method according to claim 1 or 2,

the time of the hydration reaction is 5-9 days.

5. The method according to claim 1 or 2,

the mixed solution B1 was prepared by mixing 1 part by mass of the acrylic-based waterproof coating material with 2 parts by mass of water.

6. The method according to claim 1 or 2,

the mixing and stirring time of the recycled aggregate A1 and the mixed solution B1 is 1-3 minutes, and the recycled aggregate A1 and the mixed solution B1 are placed for 3-4 hours after being stirred; the mass of the mixed solution B1 is 3-7% of the mass of the recycled aggregate A.

7. The method according to claim 1 or 2,

the mixed solution B2 was prepared by mixing 2 parts by mass of the acrylic-based waterproof coating material with 1 part by mass of water.

8. The method according to claim 1 or 2,

the mixing and stirring time of the mixed solution B2 and the recycled aggregate A2 is 1-3 minutes, and the drying time is 20-30 hours; the mass of the mixed solution B2 is 1-5% of the mass of the recycled aggregate A.

9. The method according to claim 1 or 2,

the concrete particles with the preset particle size are concrete particles with the particle size of 4.75-31.5 mm.

10. An asphalt mix comprising cement-based recycled aggregate obtained according to the method of any one of claims 1-9.

Technical Field

The invention relates to the field of road engineering solid waste recycling, in particular to a method for coating cement-based recycled aggregate for asphalt mixture.

Background

The cement-based recycled aggregate refers to aggregate with thicker grain diameter in the cement concrete solid waste, and is mainly generated from the building solid waste and the cement concrete pavement waste. At present, the recycling rate of the discharge amount of the solid wastes of the cement concrete is lower. The direct landfill or open-air stacking of the cement concrete solid waste not only occupies a large amount of land resources but also is easy to cause secondary pollution, so that the resource treatment of the cement concrete solid waste has great social requirements.

The asphalt pavement construction has the capacity of large-scale consumption of the cement concrete solid waste, and the recycling level of the solid waste can be effectively improved, but related research and engineering application experience show that the cement concrete solid waste needs to be pretreated before producing the asphalt mixture. The initial defects (mainly comprising microcracks, pores and attached powder) of the cement-based recycled aggregate and the surface attached old mortar cause the quality of the cement-based recycled aggregate to be poor and greatly differ from the quality of new aggregate. The asphalt mixture is prepared by directly adopting untreated cement-based recycled aggregate, and the following two main disadvantages exist: firstly, the old mortar and powder on the surface of the cement-based recycled aggregate can cause poor adhesion of the recycled aggregate and the asphalt mixture, so that the asphalt mixture is easy to crack, damage by water and other diseases; secondly, the use level of asphalt in the asphalt mixture is increased due to a large number of pores on the surface of the cement-based recycled aggregate, so that the material cost is increased.

The prior art for pretreating cement-based recycled aggregate mainly comprises two types: one is physical strengthening technology and the other is chemical strengthening technology. The physical strengthening technology is mainly used for removing surface adhering mortar through friction and impact by shaping strengthening equipment to realize the pretreatment of the recycled aggregate, but the physical strengthening technology is easy to cause secondary damage of the aggregate and is easy to break the edge and corner property of the aggregate, and the edge and corner property of the aggregate is important for the pavement performance of the asphalt mixture. The chemical strengthening technology is mainly characterized in that a surface treating agent is coated on the surface of aggregate, the quality of the technology depends on the surface treating agent, but the surface treating agent in the existing market has uneven quality and complex formula, and the cement-based recycled aggregate treated by the surface treating agent is mainly used for producing cement concrete, has no improved adhesion with asphalt and is not suitable for producing asphalt mixture, and in addition, the existing surface treating agent can not effectively improve the strength of the recycled aggregate.

Disclosure of Invention

The object of the present invention is to improve the strength and durability of cement-based recycled aggregate by using a slag silicate cement paste and an acrylic-based waterproof coating material in order to overcome the problems of the prior art as described above.

Means for solving the technical problem

In order to achieve the purpose, the invention adopts the following technical scheme:

a method for coating cement-based recycled aggregate for asphalt mixture is characterized by comprising the following steps:

providing concrete particles with a preset particle size as cement-based recycled aggregate A;

coating slag silicate cement slurry on the surface of the recycled aggregate A;

carrying out hydration reaction on the recycled aggregate A wrapped with the slag silicate cement paste to obtain recycled aggregate A1;

providing a mixed solution B1 prepared by mixing acrylic acid-based waterproof paint and water;

coating the mixed solution B1 on the surface of the recycled aggregate A1 to obtain recycled aggregate A2;

providing a mixed solution B2 prepared by mixing acrylic acid-based waterproof paint and water;

mixing the mixed solution B2 with the recycled aggregate A2 and drying.

Further, 2 parts by mass of slag portland cement is mixed with 1 part by mass of water to prepare a slag portland cement paste.

Further, the mixing and stirring time of the recycled aggregate A and the slag silicate cement paste is 1-3 minutes, and the recycled aggregate A and the slag silicate cement paste are placed for 20-28 hours after stirring is completed; the mass of the slag silicate cement paste is 1-3% of the mass of the recycled aggregate A.

Furthermore, the time of the hydration reaction is 5-9 days.

Further, 1 part by mass of an acrylic-based waterproof coating material was mixed with 2 parts by mass of water to prepare the mixed solution B1.

Further, the mixing and stirring time of the recycled aggregate A1 and the mixed solution B1 is 1-3 minutes, and the recycled aggregate A1 and the mixed solution B1 are placed for 3-4 hours after being stirred; the mass of the mixed solution B1 is 3-7% of the mass of the recycled aggregate A.

Further, 2 parts by mass of an acrylic-based waterproof coating material was mixed with 1 part by mass of water to prepare the mixed solution B2.

Further, the mixing and stirring time of the mixed solution B2 and the recycled aggregate A2 is 1-3 minutes, and the drying time is 20-30 hours; the mass of the mixed solution B2 is 1-5% of the mass of the recycled aggregate A.

Further, the concrete particles with the preset particle size are concrete particles with the particle size of 4.75 mm-31.5 mm.

The invention also provides an asphalt mixture, which comprises the cement-based recycled aggregate obtained by the method for coating the cement-based recycled aggregate for the asphalt mixture.

Has the advantages that:

the coating method for the cement-based recycled aggregate of the asphalt mixture has the advantages that the coating material and the operation method are simple, the recycled aggregate subjected to surface treatment has good adhesion with asphalt, the strength of the recycled aggregate is improved, and the pavement performance of the asphalt mixture is greatly improved; meanwhile, the surface pores of the recycled aggregate are greatly reduced, the using amount of asphalt is reduced, and the construction cost is saved. In addition, the invention widens the utilization approach of the cement-based recycled aggregate, realizes the high-efficiency utilization of the cement-based recycled aggregate in the asphalt mixture, improves the resource utilization rate of the cement-based recycled aggregate, and has remarkable social and economic benefits.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention and, together with the description, serve to explain the disclosed methods of the invention.

Fig. 1 is a schematic view of a cement-based recycled aggregate obtained by the coating method for a cement-based recycled aggregate for asphalt mixture according to the present invention.

List of reference numerals:

1. regenerating aggregate; 2. a portland slag cement coating; 3. an acrylic-based water repellent coating.

Detailed Description

In the following detailed description, numerous specific details are set forth in order to provide a better understanding of the invention. It will be understood by those skilled in the art that the present invention may be practiced without some of these specific details. Methods, materials, means and the like well known to those skilled in the art are not described in detail so as not to obscure the present invention.

The basic idea of the coating method of the cement-based recycled aggregate for the asphalt mixture is as follows: firstly, coating slag silicate cement paste on the surface of the cement-based recycled aggregate to enhance the strength of the recycled aggregate; and then, coating acrylic acid-based waterproof paint to reduce the pores of the recycled aggregate so as to reduce the absorption of the recycled aggregate to water/asphalt, improve the interface bonding strength between the recycled aggregate and asphalt, and finally comprehensively improve the pavement performance of the asphalt mixture based on the cement-based recycled aggregate.

The method specifically comprises the following steps:

1. the waste concrete material is crushed and screened, and concrete particles with preset particle sizes are selected as cement-based recycled aggregate, which is named as recycled aggregate A.

Preferably, concrete particles with the particle size of more than 4.75mm (millimeter) are selected, the concrete particles with the particle size of more than 31.5mm are continuously crushed, and then the concrete particles with the particle size of 4.75 mm-31.5 mm are finally selected as the cement-based recycled aggregate A.

2. And mixing the slag portland cement with water to prepare slag portland cement paste.

Preferably, 2 parts by mass of slag portland cement is mixed with 1 part by mass of water to make a slag portland cement slurry.

3. And coating slag silicate cement slurry on the surface of the recycled aggregate A.

Preferably, the recycled aggregate A and the slag silicate cement slurry are mixed and stirred for 1min (min) to 3min, and are left for 20 to 28h (h) after stirring. Wherein, the quality of the slag silicate cement paste is 1 to 3 percent of the quality of the recycled aggregate A.

More preferably, the mass of the slag silicate cement paste is 2% of the mass of the recycled aggregate A, the mixing and stirring are carried out for 2min, and the slag silicate cement paste is left for 24h after the stirring is finished. In the preferred embodiment, the mass of the portland slag cement slurry is selected to be 2% of the mass of the recycled aggregate a because the thickness of the portland slag cement slurry coating on the surface of the recycled aggregate is to be controlled. The thickness of the coating is too thin to improve the strength of the recycled aggregate. The thickness of the coating is too thick, and the surface of the recycled aggregate is easy to peel off. When the concentration is about 2%, the thickness of the coating can effectively improve the strength of the aggregate.

4. And (2) putting the recycled aggregate A wrapped with the slag silicate cement slurry into water for hydration reaction, then taking out the recycled aggregate, and naming the recycled aggregate A subjected to the hydration reaction as recycled aggregate A1.

Preferably, the time of the hydration reaction is 5-9 days. More preferably, the hydration time is 7 days.

5. The acrylic acid-based waterproof coating material was mixed with water to prepare a mixed solution B1.

Preferably, 1 part (mass part) of the acrylic-based waterproof coating material is mixed with 2 parts (mass part) of water to prepare a mixed solution B1.

The acrylic-based waterproof coating is a single-component water-emulsion waterproof coating prepared by taking a commercially available pure acrylic polymer emulsion as a base material and adding other additives. For example, Sika Tite-BE manufactured by Western Ka (China) Co.

6. And coating the mixed solution B1 on the surface of the recycled aggregate A1 to obtain recycled aggregate A2.

Preferably, the recycled aggregate A1 and the mixed solution B1 are mixed and stirred for 1min to 3min, and then are placed for 3 to 4h to obtain the recycled aggregate A2. Wherein the mass of the mixed solution B1 is 3-7% of the mass of the recycled aggregate A.

In order to effectively close the pores on the surface of the slag silicate cement slurry coating layer, it is preferable that the mass of the mixed solution B1 is 5% of the mass of the recycled aggregate A and the stirring time is 2 min.

7. The acrylic acid-based waterproof coating material was mixed with water to prepare a mixed solution B2.

Preferably, 2 parts by mass of the acrylic-based waterproof coating material is mixed with 1 part by mass of water to prepare a mixed solution B2.

8. And mixing the mixed solution B2 with the recycled aggregate A2 and drying to obtain the treated cement-based recycled aggregate, namely, finishing the coating method of the cement-based recycled aggregate for the asphalt mixture.

Preferably, the mixed solution B2 and the recycled aggregate A2 are mixed and stirred for 1-3 min, and finally dried for 20-30 h in a ventilated area. Wherein the mass of the mixed solution B2 is 1-5% of the mass of the recycled aggregate A.

More preferably, in order to further improve the surface cohesiveness of the recycled aggregate, the mass of the mixed solution B2 is 3.5% of the mass of the recycled aggregate A, the stirring time is 2min, and the drying time is 24 h.

As shown in fig. 1, the basic structure of the cement-based recycled aggregate obtained by the coating method of the present invention includes: the recycled aggregate 1 positioned at the innermost layer, the slag portland cement coating 2 wrapped outside the recycled aggregate 1, and two acrylic acid based waterproof coatings 3 wrapped outside the slag portland cement coating 2.

It should be noted that: in the coating method, the purpose of wrapping the acrylic waterproof coating on the recycled aggregate for the first time is to seal pores on the surface of the recycled aggregate, and because the acrylic waterproof coating is required to have good permeability and can well permeate into the pores, 1 part by mass of the acrylic waterproof coating is preferably mixed with 2 parts by mass of water, so that low viscosity is ensured, and good fluidity is achieved; the purpose of coating the recycled aggregate with the acrylic-based waterproof coating for the second time is to further seal some residual small pores on the surface, and the other main purpose is to enhance the adhesion of the recycled aggregate with the asphalt, so that 2 parts by mass of the acrylic-based waterproof coating is preferably mixed with 1 part by mass of water, and the proportion of the acrylic-based waterproof coating is higher so as to remarkably improve the adhesion of the recycled aggregate with the asphalt.

Examples：

1. Crushing and screening the waste concrete materials, selecting concrete particles with the particle size of more than 4.75mm, continuously crushing the concrete particles with the particle size of more than 31.5mm, and finally selecting 200kg (kilogram) of the concrete particles with the particle size of 4.75-31.5 mm as cement-based recycled aggregate A.

2. Portland slag cement of 2.66kg in mass and water of 1.34kg in mass was prepared, and the Portland slag cement was sufficiently mixed with water to prepare a Portland slag cement slurry of 4kg in total.

3. And coating slag silicate cement paste on the surface of the recycled aggregate A, wherein the mass of the slag silicate cement paste is 2% of that of the recycled aggregate A, mixing and stirring for 2min, and standing for 24h after completion.

4. And (3) putting the recycled aggregate A wrapped with the slag silicate cement slurry into water for 7 days to complete hydration reaction, and then taking out to obtain recycled aggregate A1.

5. 3.33kg of an acrylic-based waterproof coating material was mixed with 6.67kg of water, and sufficiently stirred to prepare a mixed solution B1.

6. Coating a mixed solution B1 on the surface of slag silicate cement slurry recycled aggregate A1, wherein the mass of the mixed solution B1 is 5% of that of the recycled aggregate A, mixing and stirring for 2min, standing for 3-4 h after completion, and naming the sample as the recycled aggregate A2.

7. 4.67kg of an acrylic-based waterproof coating material was mixed with 2.33kg of water to prepare a mixed solution B2.

8. Pouring the mixed solution B2 into the recycled aggregate A2, stirring for 2min, and finally drying for 24h in a ventilated area. Wherein the mass of the mixture solution B2 was 3.5% of the mass of the recycled aggregate a.

Verification example：

In order to verify the effect of the method, the asphalt mixture is prepared according to the existing technical Specification for constructing the asphalt pavement of the highway (JTG F40), and the pavement performance indexes of the recycled aggregate prepared by the coating method and the asphalt mixture adopting the original recycled aggregate (namely the recycled aggregate A) are tested. See table 1 below.

TABLE 1 road Performance test results for two asphalt mixtures

The test results in table 1 show that the asphalt usage amount of the asphalt mixture prepared from the recycled aggregate treated by the coating method of the present invention is lower than that of the asphalt mixture prepared from the original recycled aggregate, which means that the coating method of the present invention effectively reduces the surface pores of the recycled aggregate and the asphalt absorption amount, which is beneficial to saving the cost of engineering materials; on the other hand, the pavement performance index of the asphalt mixture prepared by the recycled aggregate treated by the coating method is totally higher than that of the asphalt mixture prepared by the original recycled aggregate, which shows that the interface bonding strength between the recycled aggregate and the asphalt is improved and the pavement performance of the asphalt mixture is comprehensively improved by adopting the coating method.

Embodiments of the present invention have been described above, and the above description is exemplary and not exhaustive. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the illustrated embodiments. The terms used herein are chosen to best explain the methods of the embodiments or to enable others of ordinary skill in the art to understand the disclosed embodiments of the invention.