Laboratory investigation on the properties of asphalt mixtures modified with double-adding admixtures and sensitivity analysis

In order to improve the high temperature stability and low temperature cracking resistance of asphalt mixtures, two varieties of admixtures (anti-rutting agent and lignin fiber) were selected and then combined. This is called double-mixture technology. A series of tests about pavement performance of base asphalt mixtures and asphalt mixtures with admixture of anti-rutting agent or lignin fiber were conducted. Meanwhile sensitivity analyses were used to study the influence of three factors (i.e., asphalt grade, aggregate type and gradation) on the high and low temperature performance and water stability of said asphalt mixtures. Test results indicated that the dynamic stability, residual stability, TSR and low temperature failure strain of asphalt mixtures have increased significantly with the additions of 0.40% anti-rutting agent and 0.36% lignin fiber. These results show that the high and low temperature and water stabilities of asphalt mixtures improve obviously. This supports the beneficial comprehensive effect of the double admixture. The problem of improving the asphalt mixtures performance with a single admixture is solved, in addition to also improving other pavement performance. Based on the sensitivity analysis, the most influential factors of dynamic stability, low temperature failure strain and TSR are the gradation, followed by asphalt grade and aggregate type.