Design and Water Stability Evaluation of Cold Mix Emulsified Asphalt Mixture under Multiple Freeze–Thaw Cycles

Abstract

Water stability resistance and internal void evolution behavior of the cold mix emulsified asphalt mixture (CMA) specimens at multiple freeze–thaw cycles were evaluated based on the tensile strength ratio from the indirect tensile strength (ITS) test and x-ray computed tomography (CT) test, respectively. The ITS results show that the effect of multiple freeze–thaw cycles had a more negative impact on the CMA compared to that on the hot mix asphalt, and the water stability issue of the CMA could not be ignored. Moreover, the water stability was quantified by the porosity increase and void distribution of the CMA specimens from the x-ray CT; such test results indicate that early damage of the CMA specimens after freeze–thaw cycles shown as reduced tensile strength was mainly due to the rapid increase of the number of small voids, and late damage was induced by the formation of medium and large voids within the CMA specimens. As a result, the water stability of the CMA needs to be improved before it is used as pavement surface layers in cold areas with multiple freeze–thaw cycles.