Study on the fatigue properties of bitumen emulsion-cement mastics using frequency sweep and linear amplitude sweep tests
Sajjad Jafarian, Amir Modarres
Abstract
Cold recycled mixtures with bitumen emulsion have an initial resistance problem. To reduce the rutting potential, cement is usually added which prompts significant changes in material properties. This study investigates the rheological properties of emulsion-cement mastics under short and long-term curing with emphasis on fatigue performance. The interaction of cationic and anionic bitumen emulsions with cement was separately investigated. Different ratios of cement to residual bitumen (c/b) between 0 and 0.7 were considered. In short-term curing, specimens were stored at 20°C for 3 days and in long-term curing, specimens were stored at 50°C for 7 days. Frequency sweep and linear amplitude sweep DSR tests were performed at two temperatures and the results were analyzed using the viscoelastic continuum damage theory. Also, frequency sweep test was performed at two high performance temperatures to evaluate the rutting potential of mastics. Furthermore, isothermal calorimetry test was accomplished to investigate the effect of emulsion-cement interaction on hydration progression. Based on the results anionic mastics had better fatigue performance than cationic ones. In contrast, cationic mastics showed a better rutting resistance. The fatigue life decreased at higher strains than 1% with increasing the c/b ratio, while at strains less than 1% the reverse was true.