Search

For asphalt pavement structures, semi-rigid road base course has to sustain repeated high-axle load during its service life and the performance of semi-rigid road base materials directly influences the durability of pavement structures. The dynamic compressive resilience modulus of two commonly used semi-rigid road base materials, cement stabilized aggregates (CSG) and lime-fly ash stabilized aggregates (LFSG) were evaluated at different frequencies using a Universal Testing Machine (UTM). The results showed that LFSG had higher dynamic modulus than that of CSG and the load frequency had less influence on the dynamic modulus of these two semi-rigid road base materials. The four-point bending test was applied to measure the flexural-bending strength and the fatigue life of these two semi-rigid materials. A higher flexural-bending strength of LFSG indicated its better bearing capacity than that of CSG. The fatigue life of LFSG and CSG decreased with the increase of stress–strength ratio and the LFSG performed better in terms of fatigue resistance. The fatigue damage models of CSG and LFSG based on Stress-Life (S-N) curve are established. As per incremental-recursive mechanics, a general modulus degradation model was established and verified by the results of full-scale accelerate loading test. This model cannot only be used to predict the fatigue deterioration of semi-rigid road base materials under different stress levels, but is also able to calculate the current bending elastic modulus based on its initial modulus value. [ABSTRACT FROM AUTHOR]

• Replacement of limestone powder by red mud made the asphalt mastic stiffer. • Adding red mud resulted in reduced cracking resistance, moisture damage resistance and fatigue life. • The utilization of red mud has proved to be practicable by adding a certain amount of white mud as the modification agent. With the view of reducing the consumption of non-renewable limestone resources, the waste-derived secondary resource can be considered as the limestone powder replacement for hot asphalt mixtures. This study unravels the feasibility of using a red mud-derived alternative filler aggregate to replace the commonly used limestone powder in asphalt mastics, and further improves the red-mud-modified asphalt mastic by using hydrated lime and white mud. The experimental tests, including direct tension (DT), Positest AT-A bonding strength, as well as dynamic shear rheometer (DSR), were performed to characterize the cracking resistance, the moisture damage, the fatigue behavior, as well as the rheological properties of asphalt mastic. Due to surface morphology and mineralogical composition of red mud, its replacement of limestone powder improved the elastic recovery of asphalt mastic, but it had detrimental effect on properties of the cracking resistance, the moisture damage and the fatigue life. When incorporating the hydrated lime and white mud, both materials can improve the low-temperature cracking resistance of red mud asphalt mastic. Moreover, the incorporation of the white mud into the red mud asphalt mastic can enhance its moisture resistance of aggregate-mastic bonding under both short- and long-term moisture attack as well as its fatigue resistance. [ABSTRACT FROM AUTHOR]