阅读说明：本技术 水性环氧树脂提高泡沫沥青冷再生混合料性能的方法 (Method for improving performance of foamed asphalt cold-recycling mixture by using water-based epoxy resin ) 是由 李秀君 赵麟昊 刘纪 王弘 高世柱 拾方治 董力铭 刘宁 于 2020-05-29 设计创作，主要内容包括：本发明属于泡沫沥青冷再生路面的施工技术领域,具体涉及一种水性环氧树脂提高泡沫沥青冷再生混合料性能的方法,包括以下步骤：步骤1,将水性环氧树脂加入水中,搅拌均匀后加入拌合锅；步骤2,在拌合锅内加入矿料和水泥以及泡沫沥青,搅拌后得到掺有水性环氧树脂的泡沫沥青冷再生混合料。本发明通过将水性环氧树脂作为冷拌外掺剂来制备泡沫沥青冷再生混合料,能够有效地改善泡沫沥青冷再生混合料的高温稳定性和抗水损性能。(The invention belongs to the technical field of construction of foamed asphalt cold recycling pavements, and particularly relates to a method for improving the performance of a foamed asphalt cold recycling mixture by using water-based epoxy resin, which comprises the following steps: step 1, adding waterborne epoxy resin into water, stirring uniformly, and then adding into a mixing pot; and 2, adding mineral aggregate, cement and foamed asphalt into the mixing pot, and stirring to obtain the foamed asphalt cold-recycling mixture doped with the waterborne epoxy resin. According to the invention, the foamed asphalt cold recycling mixture is prepared by taking the water-based epoxy resin as the cold mixing additive, so that the high-temperature stability and the water loss resistance of the foamed asphalt cold recycling mixture can be effectively improved.)

1. A method for improving the performance of a cold recycling mixture of foamed asphalt by using water-based epoxy resin is characterized by comprising the following steps:

step 1, adding waterborne epoxy resin into water, stirring uniformly at room temperature, and then adding into a mixing pot;

and 2, adding mineral aggregate, cement and foamed asphalt into the mixing pot, and stirring at room temperature to obtain the foamed asphalt cold-recycling mixture doped with the waterborne epoxy resin.

2. The method for improving the performance of the foamed asphalt cold recycling mixture by using the water-based epoxy resin as claimed in claim 1, wherein the method comprises the following steps:

the mixing amount of the water-based epoxy resin in the foamed asphalt cold recycling mixture is 1.5%.

3. The method for improving the performance of the foamed asphalt cold recycling mixture by using the water-based epoxy resin as claimed in claim 1, wherein the method comprises the following steps:

wherein when the construction temperature is normal temperature, the foamed asphalt cold-recycling mixture is used within 45min,

when the construction air temperature is lower or higher, the foamed asphalt cold-recycling mixture is used within 30 min.

Technical Field

The invention belongs to the technical field of construction of foamed asphalt cold recycling pavements, and particularly relates to a method for improving the performance of a foamed asphalt cold recycling mixture by using water-based epoxy resin.

Background

Foamed asphalt is a special asphalt material that is broken in a short time by injecting a certain amount of water into hot asphalt to expand its volume to form a large amount of asphalt foam. When the foamed asphalt contacts with aggregate, the asphalt foam is quickly changed into small particles which are scattered on the surface of fine aggregate (especially the particle size is less than 0.075mm) to form fine joint filling material adhered with a large amount of asphalt, and after mixing and compacting, the fine materials can be filled in the gaps of wet cold coarse materials and play a role similar to mortar, so that the mixture is stabilized.

The traditional indexes for evaluating the foaming performance of asphalt are expansion rate and half-life: the expansion ratio is defined as the ratio of the maximum volume reached by the foamed bitumen to the original volume of the unfoamed bitumen; half-life refers to the time (in s) required for the foamed bitumen to reach half of the maximum volume. Cold regeneration tests of foamed asphalt of German Vietgen company show that in order to obtain a high-quality foamed asphalt mixture, the expansion rate is more than 15, and the half-life period is within 5-10 s. Foamed asphalt disposables have inferior wear resistance to hot mix asphalt mixtures, and therefore such materials are commonly used as base or sub-base layers. Foamed asphalt as a stabilizer or a regenerant can be used for disposing various materials, and foamed asphalt can be used for disposing from poor road building materials to recycled asphalt mixture (RAP) of planing and milling.

The addition of the admixture can effectively improve the cold regeneration mixing performance of the foamed asphalt, and the common admixture can be mixed with aggregate under the action of high temperature at present, so that the performance of the mixture can be improved only by adopting a mode of modifying matrix asphalt by the admixture, but the modified asphalt has the problems of reduced foaming performance and the like. The water-based epoxy resin (WER for short) is a high molecular compound, can generate polymerization reaction at room temperature to generate a thermosetting material with a three-dimensional network structure, can effectively make up for the defects of insufficient high-temperature stability and the like of asphalt, and the polymerization product of the water-based epoxy resin obviously improves the bonding property and the frost resistance of cement mortar. Therefore, WER is gradually used as a modifier of an emulsified asphalt cold-mixing material in recent years and achieves better effect, but the application of the WER in a foamed asphalt cold-recycling mixture is not developed at home and abroad.

Disclosure of Invention

The present invention is made to solve the above problems, and an object of the present invention is to provide a method for improving the performance of a cold-recycling mix for foamed asphalt with an aqueous epoxy resin.

The invention provides a method for improving the performance of a cold recycling mixture of foamed asphalt by using a water-based epoxy resin, which is characterized by comprising the following steps of: step 1, adding waterborne epoxy resin into water, stirring uniformly at room temperature, and then adding into a mixing pot; and 2, adding mineral aggregate, cement and foamed asphalt into the mixing pot, and stirring at room temperature to obtain the foamed asphalt cold-recycling mixture doped with the waterborne epoxy resin.

The method for improving the performance of the foamed asphalt cold recycling mixture by the waterborne epoxy resin provided by the invention can also have the following characteristics: wherein the mixing amount of the water-based epoxy resin in the foamed asphalt cold recycling mixture is 1.5 percent.

The method for improving the performance of the foamed asphalt cold recycling mixture by the waterborne epoxy resin provided by the invention can also have the following characteristics: wherein, when the construction temperature is normal temperature, the foamed asphalt cold-recycling mixture is used within 45min, and when the construction temperature is lower or higher, the foamed asphalt cold-recycling mixture is used within 30 min.

Action and Effect of the invention

According to the method for improving the performance of the foamed asphalt cold recycling mixture by using the waterborne epoxy resin, which is disclosed by the invention, the foamed asphalt cold recycling mixture is prepared by using the waterborne epoxy resin as a cold-mixing external additive, so that the high-temperature stability and the water loss resistance of the foamed asphalt cold recycling mixture can be effectively improved.

Drawings

FIG. 1 is a schematic microstructure of a conventional foamed asphalt cold mix in an embodiment of the present invention;

FIG. 2 is a schematic flow diagram of a method for enhancing the performance of a cold-recycling mix for foamed asphalt with an aqueous epoxy resin in an embodiment of the present invention;

FIG. 3 is a schematic microstructure of a foamed asphalt cold-mix incorporating an aqueous epoxy resin according to an embodiment of the present invention;

FIG. 4 is a comparison of the appearance of test pieces with 1.5% and 0% of aqueous epoxy resin in examples of the present invention;

FIG. 5 is an ITSR, void fraction and dynamic stability of a foamed asphalt cold-recycled mix with different incorporation patterns and amounts of aqueous epoxy resin in an example of the present invention;

FIG. 6 is a curing process of a waterborne epoxy resin at different storage temperatures in an embodiment of the present invention;

FIG. 7 is a graph of the dynamic stability and ITSR of a foamed asphalt cold-mix at various storage times and storage temperatures in examples of the invention.

Detailed Description

In order to make the technical means and functions of the present invention easy to understand, the present invention is specifically described below with reference to the embodiments and the accompanying drawings.

FIG. 2 is a schematic flow diagram of a method for enhancing the performance of a cold-recycling mix for foamed asphalt with an aqueous epoxy resin in an embodiment of the present invention.

As shown in fig. 2, this example provides a method for improving the performance of a cold-recycling mixture of foamed asphalt with a water-based epoxy resin, which includes the following steps:

step 1, adding the waterborne epoxy resin into water, stirring uniformly at room temperature, and then adding into a mixing pot.

The stirring time in the step 1 is 10s-20 s.

And 2, adding mineral aggregate, cement and foamed asphalt into the mixing pot, and stirring at room temperature to obtain the foamed asphalt cold-recycling mixture doped with the waterborne epoxy resin.

In the embodiment, the stirring speed of the mixing pot is 60rad/min, mineral aggregate and cement are added into the mixing pot according to the proportion in the step 2, water is sprayed into the mixing pot, the mixture is stirred for 5-10 s, foamed asphalt is sprayed into the mixing pot, and finally the mixture is stirred for 10-20 s, so that the foamed asphalt cold recycling mixture doped with the water-based epoxy resin is obtained.

In the embodiment, the Waterborne Epoxy Resin (WER) can be subjected to polymerization reaction at room temperature to generate a three-dimensional network structure, so that the defects of insufficient high-temperature stability and the like of asphalt can be effectively overcome, and the cracking resistance of cement mortar can be improved by a polymerization product of the waterborne epoxy resin.

FIG. 3 is a schematic microstructure of a foamed asphalt cold mix incorporating an aqueous epoxy resin according to an embodiment of the present invention.

As shown in fig. 3, the principle of WER improving the performance of the foamed asphalt cold recycling mixture is as follows: firstly, in the process of mixing the mixture, the WER can independently wrap loose fine aggregates to form epoxy resin mucilage, and a polymerization product with strong cohesiveness and high compactness is generated along with the evaporation of water. Secondly, the WER can fill larger gaps of cement mortar, so that the number of the gaps is reduced, and the structural compactness is improved; and a proper amount of WER can form a cross-linked structure in the foamed asphalt mortar, has interlocking and reinforcing effects on asphalt particles and the mortar, and can improve the compactness and stability of the asphalt mortar (as shown in figure 4). Therefore, the WER can be used as an ideal modifier for improving the pavement performance of the foamed asphalt cold recycling mixture.

In this embodiment, three different adding modes of WER are also compared: the method 1 is that WER is prepared first, and then the WER, mineral aggregate, cement, asphalt and water are added into a mixing pot; adding the prepared WER into water, uniformly stirring, and adding the WER, the mineral aggregate, the cement and the asphalt into a mixing pot; and the mode 3 is that the prepared WER is added into the mixture and stirred uniformly when the production of the foamed asphalt cold recycling mixture is finished.

FIG. 5 is a graph showing the ITSR, porosity and dynamic stability of a foamed asphalt cold-recycled mix in examples of the present invention at different modes and amounts of incorporation of the aqueous epoxy resin.

As shown in fig. 5, the optimal blending process is obtained as mode 2 under the condition of ensuring the consistency of the total blending time of the three blending modes.

In this embodiment, on the basis of considering the performance improvement effect and the economical efficiency of the WER on the asphalt cement, the water stability of the WER corresponding to the foamed asphalt cold-recycling mixture at four doping amounts of 0.5%, 1.0%, 1.5% and 2.0% (by forming and maintaining a standard marshall test piece of the foamed asphalt cold-recycling mixture, the void ratio of the test piece is tested and the cleavage test is performed, the water loss resistance of the mixture is represented by the dry-wet cleavage strength ratio) and the high temperature stability (by forming and maintaining a rut test piece, the rut test at 60 ℃ is performed, the high temperature stability of the mixture is represented by the dynamic stability), and finally the doping amount of the water-based epoxy resin in the foamed asphalt cold-recycling mixture is 1.5%.

In this embodiment, the performance analysis of the foamed asphalt cold-recycling mixture is performed at different storage times and storage temperatures, and the specific process is as follows: the temperature has great influence on the WER curing reaction speed (as shown in figure 6), the cement hydration speed and the plasticity of the foamed asphalt mortar. Because the construction temperature difference in different seasons is large, when the influence of the storage time on the performance of the mixture is analyzed, the temperature of the mixture during storage needs to be considered, and therefore the storage temperatures of 20 ℃, 30 ℃ and 40 ℃ are set according to common construction temperatures to carry out dry and wet splitting tests.

FIG. 7 is a graph of the dynamic stability and ITSR of a foamed asphalt cold-mix at various storage times and storage temperatures in examples of the invention.

As shown in FIG. 7, the water damage resistance and the high temperature stability of the mixture decrease with the increase of the storage time, wherein the water damage resistance of the mixture decreases to a small extent within 30min, and after 45min, the water damage resistance of the mixture decreases to a large extent when the storage temperature is 20 ℃ and 40 ℃, even the mixture does not meet the requirement of the specification limit. Therefore, in order to fully exert the improvement effect of WER, the prepared foamed asphalt cold-recycling mixture is recommended to be conveyed to the site for paving and compacting within 45min at normal temperature, and when the construction temperature is lower or higher, the transportation time is preferably controlled within 30 min.

The mixture water loss resistance of the foamed asphalt cold recycling mixture prepared by the method for improving the performance of the foamed asphalt cold recycling mixture through the waterborne epoxy resin can be improved by about 10%, the high-temperature stability is respectively improved by 30-50%, the asphalt foaming performance under the preparation method is not affected, and the operability is very high in the construction process.