The Use of Reclaimed Epoxy Asphalt Materials in Asphalt Mixtures and Cement Concrete Mixes

Abstract

Designing long-life pavements and pavement recycling with reclaimed asphalt pavement (RAP) are two important strategies for improving the sustainability of asphalt pavements. Epoxy asphalt, as a proven long-life pavement material, is attracting attention from the pavement community for its use in road pavements. The recyclability of epoxy asphalt mixtures, however, has never been studied and has now become one concern in promoting the use of epoxy asphalt binder (or simply referred to as “epoxy binder”) in road pavements including flexible and rigid pavements. First, this research attempts to explore the performance of hot mix asphalt (HMA) containing reclaimed epoxy asphalt materials (hereinafter referred to as “epoxy RAP”). Epoxy RAP materials were incorporated into regular asphalt mixtures at various contents. Specimens were prepared and tested for their performance in comparison with mixtures without RAP. Since epoxy binder dilution is a legitimate practice by road agencies to reduce the material cost, epoxy binder was diluted by conventional binder at a ratio of 1:3. Performance of HMAs containing reclaimed diluted epoxy asphalt materials (hereinafter referred to as “diluted epoxy RAP”) was also investigated and compared with asphalt mixtures containing epoxy RAP (hereinafter referred to as “epoxy RAP mixtures”). Results showed that replacing the coarse aggregates in HMA with epoxy RAP and diluted epoxy RAP up to 80% did not negatively affect its Marshall stability, tensile strength, and moisture resistance. Improvements of Marshall stability, tensile strength, and moisture resistance results were noticed at asphalt mixtures containing 40% diluted epoxy RAP. This indicated that diluted epoxy RAP binder might be partially blended with conventional binder x during mixing. To validate this assumption, blends of diluted epoxy RAP binder and conventional binder were investigated using regular dynamic shear rheometer test (DSR), DSR multiple stress creep recovery (MSCR) test, DSR linear amplitude sweep (LAS) test, Fourier transform infrared spectroscopy (FTIR) test, and scanning electron microscopy (SEM). Results from these tests showed that there was blending between two binders. In addition, Portland cement concrete mixes containing 100% epoxy RAP and 100% diluted epoxy RAP with and without silica fume were fabricated and tested. The objective of this study was to compare pervious concrete mixes containing epoxy RAP particles (undiluted/diluted) with others containing regular RAP evaluated by many previous studies. Density test, permeability test, and compressive strength test were used to assess concrete mixes. Results showed similar performance to those mixes with regular RAP materials in terms density, permeability and compressive strength. It can be concluded from this research that the use of epoxy RAP materials in either asphalt mixtures or cement concrete mixes might be considered as a sustainable option for the road industry in the near future, as environmental and economic benefits could be realized.