Laboratory evaluation of the composition of nano-clay, nano-lime and SBS modifiers on rutting resistance of asphalt binder

The physical and rheological properties of asphalt mixtures affect pavement performance at high and low ambient temperatures, and thus can affect the final performance of the mixture. Adding modifiers such as polymers and nano additives to improve asphalt mixture performance has become popular in recent years. The purpose of this study is to modify the bitumen with nano-clay, nano-lime and Styrene-Butadiene-Styrene (SBS). PG 64-22 bitumen was modified using 2, 4 and 6 wt% of nano-clay and the results showed that increasing the nano-clay to the base bitumen improved the rheological properties and rutting resistance of asphalt binder. Also, it was examined the effect of adding 3% SBS to the bitumen sample, and the results indicated a positive effect of this additive, especially at lower temperatures. In the next step, bitumen was modified using 4 and 6 wt% of nano-lime and 3% SBS with 4 and 6 wt% of nano-clay in combination with the base bitumen and tested to evaluate the combined effect of these three materials. The effect of this modifier on reducing rutting failure was evaluated compared to the control sample. To this end, we evaluated the effect of these materials on the rheological properties of bitumen by performing multiple stress creep recovery (MSCR) test by Dynamic Shear Rheometer (DSR). Results showed that increasing the nano-clay to the base bitumen improved the rheological properties and rutting resistance of asphalt binder and best improvement is achieved with 6%. The effect of 3% SBS although did not produce results similar to nano-clay, but the results showed significant improvement in bitumen properties. Finally, the best combination in this study was a combination of 3% SBS, 4% nano-clay, and 6% nano-lime, which yielded good results. (C) 2019 Elsevier Ltd. All rights reserved.