Preparation And Properties Of Waterborne Epoxy Modified CRTSⅡ Cement Asphalt Mortar

The CRTSâ…¡ballastless slab track is one of main high-speed railway track structurre. Cement emulsified asphalt mortar is important component of slab track structure. In the rainy season, water can permeate into mortar under hydrostatic pressure, which causes the decreasing of adhesivity of asphalt fim with cement hydrate under mechanical loading combining with water pressure gradually. Acid gas, alkaline environment and oil leak from locomotive are also the reasons of leading to failure of the adhesivity between binder and sand in mortar,resulting in some pot holes, crack and void between slab and cushion, which seriously impact the life and safety of the board slab track.Therefore, the durability of mortar has a very important practical significance.This article through phase transforming method to preparing waterborne epoxy resin, using SK-90 for preparing waterborne epoxy modified emulsified asphalt and waterborne epoxy modified cement emulsified asphalt mortar. The effect of waterborne epoxy on emulsified bitumen of adhesion, softening point and penetration were investigated, the microstrcture of waterborne epoxy modified emulsified asphalt was characterized by fluorescent microscope. Discussed the cement admixture, waster rubber powder, fiber and penetration crystallization materials powder on influence on the performance of the modified cement mortar on the basis of determining the proportion and mortar mixing, maintenance way. Emphatically analyzes the effect of waterborne epoxy resin on mortar mechanic properties, freezing-thawing, corrosion resistance and resistance to fatigue. The main conclusions are as follows:1.The softening point of emulsified bitumen residue was improved by adding waterborne epoxy, but the penetration had declined. The adhesion of the waterborne epoxy modified emulsified asphalt was significantly better than which modifed by butyl benzene latex and polychloroprene latex,when the content of waterborne epoxy was 5%.2.The mechanical properties of the cement emulsified asphalt mortar can be improved by both fly ash and silica fume, the effect of fly ash on fluidity was obvious increased, however, can, the flexural strength of the mortar was enhanced dy rubber powder,which increased toughness of mortar; Fiber can significantly increased the mechanical performance and reduced the mortar mortar stratified degrees. The crystalline materials can obviously improve flexural, compressive strength,when the content is 2% of cement.3.Compared with unmodified mortar, the compressive strength, flexural strength and bond strength of modified cement emulsified asphalt mortar were improved 15.1%,22.4% and 37%, respectively, while the content of waterborne epoxy was 5% of emulsified asphalt. The effect of a small amount of waterborne epoxy on the mechanical property of mortar were obvious at early curing stage of mortar, furthermore, at later stage, the trend of increase of strength was smooth.4.The droop rates of the compressive strength, flexural strength of modified cement emulsified asphalt mortar were lower than that of unmodified mortar, after 56 cycles of freezing-thawing. Moreover, with the increase of freezing-thawing cycles, the difference of flexural strength between modified mortar and contrast sample was more distinct.5.The acid and alkali corroding resistance of modified cement emulsified asphalt mortar were enhanced effectively, compared with unmodified mortar. Additionally, the effect of alkali corroding on mechanical property of mortar were more evident.6.After 10000 cycles of freezing-thawing, the compressive strength retention rate of modified cement emulsified asphalt mortar was 105% of that of unmodified mortar, and the diversity between modified mortar and contrast sample were more clear with the increase of freezing-thawing cycles. It could be attributed to the formation of network structure of waterborne epoxy in mortar system, which could be increased the bond strength between asphalt and mortar, in other words, the fatigue resistance of mortar was improved effectively due to building a bridge between organic and inorganic.