Performance of a dry-method-epoxy modifier and a modified epoxy-asphalt mixture

Conventional epoxy asphalt and its mixtures have a complex application procedure that leads to poor stability, easy segregation, and strict on-the-spot preparation requirements and applications. To solve these issues, the performance of a mixture of a customized dry-method-epoxy modifier and its asphalt mixture was evaluated. Functional groups before and after curing were analyzed using Fourier transform infrared spectrometry; the curing behavior was analyzed by non-isothermal differential scanning calorimetry tests; an optical microscope was used to observe the dispersibility of the dry-method-epoxy modifier in the asphalt, determine the optimal mixing ratio of the dry-method-epoxy modifier and the asphalt through the dispersibility, and observe the curing state. The relationship between the factors influencing the construction and road performance of dry-method-epoxy-asphalt mixture was evaluated using an orthogonal test and the Gray situation-decision method. The performance of the mixture under optimized conditions was then examined, and the results indicate that our modifier was exposed to a completed reaction at high temperatures. The curing heat decreased with increase in heating rate, resulting in a reduced reaction degree. The calculations demonstrated that the curing of dry-method-epoxy modifier is an approximately first-order reaction, although the reaction exotherm is concentrated and its tendency is high. Moreover, orthogonal tests were used to formulate 16 test plans for five factors and four levels of dry-method-epoxy asphalt mixture. The optimized conditions determined through the orthogonal test and the Gray situation-decision method were gradation = EA10, oil–stone ratio = 4.5, curing temperature = 150 °C, curing time = 4 h, and retention time = 30 min. Considering the realistic factors, an optimized scheme was determined and applied to assess the road performance of dry-method-epoxy-asphalt mixture. Based on the test, the Marshall stability was up to 65.28 kN, the dynamic stabilities at 60 °C and 70 °C were 43,200 and 27,391 times mm−1, respectively, the freeze–thaw-splitting-strength ratio was 109%, the residual water-stability ratio was 96.2%, and the low temperature bending maximum flexural-tension strain was 3562 μe. This study confirmed the performance of dry-method-epoxy modifier and its mixtures with asphalt, thus providing theoretical guidance for practical applications.