Improved Performance of Natural Rubber Latex–Modified Asphalt Concretes with Various Types of Aggregates

Abstract

The influence of aggregate properties and natural rubber latex (NRL) additive on the performance of natural rubber modified asphalt (NRMA) concrete mixtures was investigated. The NRMA mixtures were prepared using three types of aggregate (granite, limestone, and basalt), asphalt cement AC60/70 and NRL with different rubber to binder (R/B) ratios of 3%, 5%, and 7%. A series of laboratory tests including Marshall stability and flow, indirect tensile strength, indirect tensile fatigue, resilient modulus, wheel tracking test, dynamic creep, and skid resistance tests were conducted to investigate the mechanical properties and mechanistic performance of the NRMA mixtures. Statistical analysis was performed using the NLOGIT software program to evaluate the influence factors including strength, shape, and chemical properties of aggregate and R/B ratio. The R/B ratio of 3% was found to be the optimum value which provided the best mechanical properties and performance. The strength parameters and mineral compound were found to control the Marshall stability. As such, the NRMA mixtures with basalt and granite of high Marshall stability led to the high resilient modulus, rutting resistance, and permanent deformation. Because of the good strength and shape parameters of granite, the NRMA mixture with granite indicated a significant rate of improvement of fatigue life compared with the NRMA mixtures with other aggregates. Limestone’s predominant mineral compounds (CaO, MgO, and SiO2) were found to influence the indirect tensile strength and skid resistance of NRMA mixtures.