A permeable emulsified asphalt concrete and a method for preparing the same

Abstract

The application discloses a water-permeable emulsified asphalt concrete and a preparation method thereof, which is prepared from the following components in parts by mass: coarse aggregate 50-70 parts, cement 20-25 parts, modified emulsified asphalt 5-10 parts, cementing agent 0-5 parts and water 5-10 parts; wherein the modified emulsified asphalt is prepared from the following components in parts by mass: asphalt 40-60 parts, anionic emulsion 20-30 parts, rubber powder 20-25 parts and anti-stripping agent 0-5 parts. The modified emulsified asphalt prepared by the application is suitable for low-temperature storage, and the prepared water-permeable emulsified asphalt concrete has the advantages of high concrete strength, high-temperature anti-rutting performance and wear resistance.

Description

Technical Field

[0001] This invention relates to the field of asphalt concrete technology, specifically to a permeable emulsified asphalt concrete and its preparation method. Background Technology

[0002] Currently, with the national initiative to build sponge cities underway, permeable concrete, as an important indicator of the transformation of urban development concepts and construction methods, is receiving increasing attention. However, due to the unique skeletal pore structure of permeable concrete, the bonding area between cement paste and aggregates is reduced, and the contact points between aggregates decrease, resulting in insufficient mechanical properties of the concrete. While permeable asphalt concrete, prepared by replacing cement with asphalt, can solve the problem of low strength in permeable cement concrete, it suffers from poor permeability and resistance to flexural deformation, making it prone to cracking and severe pavement wear under vehicle loads. Using modified emulsified asphalt to replace the base asphalt in permeable concrete addresses this issue. The stripping agent in the modified emulsified asphalt not only increases the adhesion between the asphalt and aggregates, improving strength, but the entire production process is also carried out at room temperature, eliminating the need for on-site heating and other special procedures, thus reducing energy consumption and environmental pollution, which is highly beneficial for achieving civilized and environmentally friendly construction. Furthermore, modifying emulsified asphalt with rubber powder can improve the resistance to irreversible plastic deformation under load, preventing pavement settlement and rutting.

[0003] Currently, in response to the problems of low strength, poor permeability, and poor resistance to rutting at high temperatures in permeable asphalt concrete, many professional technicians are starting with the modification of emulsified asphalt and seeking the best solution through continuous technological innovation.

[0004] Chinese patent CN105601947A discloses an emulsified asphalt with asphalt, water and compound emulsifier as the main components, which is suitable for the field of road construction. It solves the problem of insufficient stability of current emulsified asphalt, but does not mention the plastic deformation of asphalt under high temperature conditions and the resulting road settlement and rutting problems.

[0005] Chinese patent CN10839255A discloses a modified asphalt, whose main components are SBS modified matrix asphalt, modified rubber, high viscosity agent and ceramic fiber. This modified asphalt has strong adhesion. Permeable asphalt concrete made from this modified asphalt can reduce the amount of fine aggregate and improve the permeability of the road, but the production cost is high and the amount of modified asphalt is large.

[0006] Chinese patent CN108751833A discloses a high-strength cement emulsified asphalt mixture, with aggregates, cement, minerals, emulsified asphalt, water-reducing agent and wetting agent as the main components. The strength of the emulsified asphalt mixture is improved by adding water-reducing agent and wetting agent, but the bonding effect of emulsified asphalt is not mentioned.

[0007] The inventions mentioned above mainly focus on improving the storage stability and viscosity of emulsified asphalt and the permeability of permeable asphalt concrete, but do not mention the mechanical properties of permeable asphalt concrete, nor do they effectively solve the problems of road settlement and rutting caused by plastic deformation of high-temperature asphalt. Summary of the Invention

[0008] The technical problem to be solved by this invention is to provide a permeable emulsified asphalt concrete and its preparation method, thereby solving the problems of road surface settlement and rutting caused by plastic deformation of asphalt at high temperatures.

[0009] The technical solution of this invention is as follows:

[0010] A permeable emulsified asphalt concrete is prepared by mixing the following components in the following mass ratio: 50-70 parts coarse aggregate, 20-25 parts cement, 5-10 parts modified emulsified asphalt, 0-5 parts binder, and 5-10 parts water.

[0011] The modified emulsified asphalt is prepared by mixing the following components in the following mass ratios: 40-60 parts asphalt, 20-30 parts anionic emulsion, 20-25 parts rubber powder, and 0-5 parts anti-stripping agent.

[0012] The cement is one or a mixture of silicate cement and sulfoaluminate cement; the coarse aggregate is one or a mixture of 5-10mm limestone, 10-16mm limestone, 5-10mm basalt and 10-20mm basalt; the binder is one or a mixture of fly ash and silica fume.

[0013] The asphalt is selected from one or a mixture of two of petroleum asphalt, natural asphalt, and modified asphalt.

[0014] The anionic emulsion is prepared by mixing the following components in the following mass ratios: 0.6-0.8 parts anionic emulsifier, 0.01-0.03 parts stabilizer, 5-8 parts pH adjuster, and 991.17-994.39 parts water.

[0015] The anionic emulsifier is one or a mixture of two of the following: sulfonate surfactants with a solid content of 40-60%, carboxylate surfactants with a solid content of 20-40%, and sulfate surfactants with a solid content of 10-50%.

[0016] The pH adjuster is one or a mixture of two of sodium hydroxide with a solid content of 10-20% and potassium hydroxide with a solid content of 10-20%.

[0017] The stabilizer is selected from one or a mixture of two of the following: hydroxyethyl cellulose with a molecular weight of 30,000-60,000, carboxymethyl cellulose with a molecular weight of 30,000-60,000, and hydroxypropyl methyl cellulose with a molecular weight of 50,000-100,000.

[0018] The rubber powder is selected from one or a mixture of two of the following: coarse rubber powder with a mesh size of 20-40, fine rubber powder with a mesh size of 40-80, and micro-fine rubber powder with a mesh size of 80-200; the anti-stripping agent is selected from one or a mixture of two of the following: an anti-stripping agent with a viscosity of 900 cps, an anti-stripping agent with a viscosity of 1500 cps, and an anti-stripping agent with a viscosity of 2000 cps.

[0019] A method for preparing permeable emulsified asphalt concrete specifically includes the following steps:

[0020] (1) Preparation of modified emulsified asphalt:

[0021] Weigh out asphalt, anionic emulsion and anti-stripping agent by weight, put them into a high-speed shear mixing mill, shear at high speed for 1-2 minutes, and circulate three times to obtain a uniform emulsion. Weigh out the uniform emulsion at 40-60℃ and rubber powder by weight and mix them to obtain modified emulsified asphalt.

[0022] (2) Mix coarse aggregate and half water according to the mass ratio, then add cement, binder, modified emulsified asphalt and the remaining half water according to the mass ratio, and continue mixing to prepare permeable emulsified asphalt concrete.

[0023] In step (1), the stirring speed of the uniform emulsion and rubber powder is 20-30 r / min, and the stirring time is 20 min.

[0024] Advantages of this invention:

[0025] (1) The present invention uses rubber powder as an elastic modifier to modify emulsified asphalt. The prepared permeable emulsified asphalt concrete has the performance characteristics of both permeable asphalt concrete and permeable cement concrete. It can improve the problem of low strength of permeable concrete, improve the bending deformation resistance of permeable asphalt concrete, prevent cracking under vehicle load, and solve the settlement and rutting phenomenon caused by large load.

[0026] (2) The present invention uses anionic emulsion as a stabilizer for modified emulsified asphalt. The modified emulsified asphalt and permeable emulsified asphalt concrete prepared have stable performance. The storage stability of the modified emulsified asphalt is less than 0.5% after one day. The main performance indicators (Marshall test technical standards) of the prepared permeable emulsified asphalt concrete meet the performance technical standards of permeable asphalt concrete.

[0027] (3) This invention adjusts the acidity and alkalinity of the anionic emulsion by pH adjuster, thereby controlling the demulsification rate of modified emulsified asphalt in coarse aggregate. The demulsification of emulsified asphalt relies on the adhesion between the asphalt itself and the aggregate to squeeze out water. Asphalt emulsifiers generally rely on oxygen atoms for hydrophilicity. The oxygen atoms form hydrogen bonds with water, which slows down water evaporation. The hydrogen bond effect is enhanced under acidic conditions and weakened under alkaline conditions. Therefore, by controlling the pH value of modified emulsified asphalt, the demulsification rate can be controlled so that the modified emulsified asphalt does not demulsify during the mixing process of permeable emulsified asphalt concrete and can be quickly demulsified and formed after mixing.

[0028] (4) Due to the unique skeleton pore structure of permeable concrete, the bonding area between cement and coarse aggregate is reduced, the contact points between coarse aggregate are reduced, and the total bonding force and mechanical interlocking force inside the concrete are reduced, resulting in insufficient strength. Therefore, this invention uses modified emulsified asphalt and anti-stripping agent as binders to increase the adhesion between asphalt and coarse aggregate, thereby improving the strength of permeable emulsified asphalt concrete (28-day strength exceeds 30 MPa).

[0029] (5) The modified emulsified asphalt prepared by this invention has a lower asphalt content than ordinary permeable asphalt concrete, is easier to construct, is green and environmentally friendly, and reduces harm to the human body and environmental pollution. Detailed Implementation

[0030] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] A method for preparing permeable emulsified asphalt concrete specifically includes the following steps:

[0032] (1) Preparation of modified emulsified asphalt:

[0033] Weigh out asphalt, anionic emulsion and anti-stripping agent according to the mass fraction, put them into a high-speed shear mixing mill, shear at high speed for 1-2 minutes, and circulate three times to obtain a uniform emulsion. Weigh out the uniform emulsion at 40-60℃ and rubber powder according to the mass fraction, and stir and mix them at a stirring speed of 20-30 r / min for 20 minutes to obtain modified emulsified asphalt.

[0034] (2) Mix coarse aggregate and half of water according to the mass ratio and stir for 30s. Then add cement, binder, modified emulsified asphalt and the remaining half of water according to the mass ratio and continue stirring for 120s to prepare permeable emulsified asphalt concrete.

[0035] The following examples illustrate the formulation and analysis of this invention:

[0036] The proportions of anionic emulsions in Examples 1-3 and Comparative Examples 1-6 are shown in Table 1, the proportions of modified emulsified asphalt are shown in Table 2, and the proportions of permeable asphalt concrete are shown in Table 3. In Tables 1-3, "—" represents none.

[0037] Table 1. Composition of Anionic Emulsions (Unit: Parts)

[0038]

[0039]

[0040] Table 2. Composition of Modified Emulsified Asphalt (Unit: Parts)

[0041]

[0042]

[0043] Table 3. Composition of Permeable Asphalt Concrete (Unit: Parts)

[0044]

[0045] The component proportions of the permeable asphalt concrete in Comparative Examples 1-6 are the same as in Example 1.

[0046] The manufacturers and models of the raw materials used in Examples 1-3 and Comparative Examples 1-6 are as follows: petroleum asphalt, natural asphalt, and modified asphalt were produced by Feicheng Yongda Engineering Materials Co., Ltd.; rubber powder, including coarse, fine, and micro-fine rubber powder, was produced by Shandong Huitong Rubber Co., Ltd. and Cangzhou Ruifeng Rubber Co., Ltd.; anti-stripping agents of 900 cps, 1500 cps, and 2000 cps were produced by Guangdong Qingxu Chemical Technology Co., Ltd. and Fengqiu Dayang Chemical Materials Co., Ltd.; anionic emulsifiers, including sulfonate surfactants, carboxylate surfactants, and sulfate surfactants, were produced by BASF Group (Germany) and IDC (Japan); stabilizers, including hydroxyethyl cellulose, carboxymethyl cellulose, and hydroxypropyl methyl cellulose, were produced by Feicheng Yutian Chemical Co., Ltd. and Renqiu Haoyu Chemical Co., Ltd.; and pH adjusters, sodium hydroxide and potassium hydroxide, were produced by Tianjin Tongxin Chemical Plant.

[0047] The modified emulsified asphalt and permeable asphalt concrete prepared in Examples 1-3 and Comparative Examples 1-6 were tested, and the test results are shown in Table 4.

[0048] Table 4 Performance Test Results

[0049]

[0050]

[0051] As shown in Tables 1-4, the modified emulsified asphalt prepared in Examples 1-3 exhibits good storage stability, good compressive strength and permeability coefficient of the permeable emulsified asphalt concrete, and high Marshall stability and rutting stability. In Comparative Example 1, the weight percentages of rubber powder and pH adjuster are lower than the ranges defined in this patent, resulting in demulsification of the emulsified asphalt (poor storage stability), and a decrease in both Marshall stability and rutting stability of the permeable emulsified asphalt concrete. In Comparative Example 2, the weight percentages of rubber powder and pH adjuster are higher than the ranges defined in this patent, leading to increased residue on the modified asphalt sieve, poorer low-temperature storage stability, and a decrease in compressive strength. In Comparative Example 3, the weight percentage of asphalt is lower than the range defined in this patent, and the weight percentages of rubber powder are higher than the ranges defined in this patent. Within the range defined by the components of this patent, the modified emulsified asphalt exhibits increased residue on the sieve, decreased compressive strength, and reduced Marshall stability and rutting stability. In Comparative Example 4, the asphalt weight percentage is higher than the range defined by the components of this patent, resulting in increased residue on the sieve, poorer one-day and five-day storage stability, and poorer low-temperature storage stability. In Comparative Example 5, both the anionic emulsion weight percentage and the anti-stripping agent weight percentage are higher than the range defined by the components of this patent, leading to decreased compressive strength, decreased Marshall stability and rutting stability, and poorer permeability. In Comparative Example 6, the anionic emulsion weight percentage is lower than the range defined by the components of this patent, resulting in increased residue on the sieve, poorer one-day and five-day storage stability, poorer low-temperature storage stability, and decreased compressive strength.

[0052] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A permeable emulsified asphalt concrete, characterized by: This permeable emulsified asphalt concrete is prepared by mixing the following components in the specified mass ratios: 50-70 parts coarse aggregate, 20-25 parts cement, 5-10 parts modified emulsified asphalt, 0-5 parts binder, and 5-10 parts water; The modified emulsified asphalt is prepared by mixing the following components in the following mass ratios: 40-60 parts asphalt, 20-30 parts anionic emulsion, 20-25 parts rubber powder, and 0-5 parts anti-stripping agent. The anionic emulsion is prepared by mixing the following components in the following mass ratios: 0.6-0.8 parts anionic emulsifier, 0.01-0.03 parts stabilizer, 5-8 parts pH adjuster, and 991.17-994.39 parts water. The anionic emulsifier is one or a mixture of two of the following: sulfonate surfactants with a solid content of 40-60%, carboxylate surfactants with a solid content of 20-40%, and sulfate surfactants with a solid content of 10-50%. The pH adjuster is one or a mixture of two of sodium hydroxide with a solid content of 10-20% and potassium hydroxide with a solid content of 10-20%. The stabilizer is selected from one or a mixture of two of the following: hydroxyethyl cellulose with a molecular weight of 30,000-60,000, carboxymethyl cellulose with a molecular weight of 30,000-60,000, and hydroxypropyl methyl cellulose with a molecular weight of 50,000-100,000. Its preparation method includes the following steps: (1) Preparation of modified emulsified asphalt: Weigh asphalt, anionic emulsion and anti-stripping agent according to the mass parts, put them into a high-speed shear mixing mill, shear at high speed for 1-2 minutes, and circulate three times to obtain a uniform emulsion. Weigh the uniform emulsion at 40-60℃ and rubber powder according to the mass parts and stir to mix evenly to obtain modified emulsified asphalt. (2) Mix coarse aggregate and half water according to the mass ratio, then add cement, binder, modified emulsified asphalt and the remaining half water according to the mass ratio, and continue mixing to prepare permeable emulsified asphalt concrete.

2. The permeable emulsified asphalt concrete according to claim 1, characterized by: The cement is one or a mixture of silicate cement and sulfoaluminate cement; the coarse aggregate is one or a mixture of 5-10mm limestone, 10-16mm limestone, 5-10mm basalt and 10-20mm basalt; the binder is one or a mixture of fly ash and silica fume.

3. The permeable emulsified asphalt concrete according to claim 1, characterized by: The asphalt is selected from one or a mixture of two of petroleum asphalt, natural asphalt, and modified asphalt.

4. The permeable emulsified asphalt concrete according to claim 1, characterized by: The rubber powder is selected from one or a mixture of two of the following: coarse rubber powder with a mesh size of 20-40, fine rubber powder with a mesh size of 40-80, and micro-fine rubber powder with a mesh size of 80-200; the anti-stripping agent is selected from one or a mixture of two of the following: an anti-stripping agent with a viscosity of 900 cps, an anti-stripping agent with a viscosity of 1500 cps, and an anti-stripping agent with a viscosity of 2000 cps.

5. The permeable emulsified asphalt concrete according to claim 1, characterized by: In step (1), the stirring speed of the uniform emulsion and rubber powder is 20-30 r / min, and the stirring time is 20 min.

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