Effects of Compaction Efforts on Tensile Strength Characteristics And Durability of Warm-asphalt Mixture Containing Natural And Synthetic Zeolite

Abstract

Many studies have been conducted to evaluate the mechanical properties of warm-mix asphalt (WMA) mixtures using Natural Zeolite (NZ) and Synthetic Zeolite (SZ) without considering the impact of compaction efforts. In this study, the influence of compaction cycles on the mechanical characteristics of WMA mixtures including NZ & SZ additives, is studied and compared with hot mix asphalt (HMA) mixtures. The amount of NZ and SZ used to make the WMA mixes was 5% of the whole asphalt mass. For the research, six WMA mixtures with a penetration grade of 40-50 were designed and compared to HMA traditional mixture. HMA &WMA mixtures were designed with 35, 50 and 75 compaction efforts. Mechanical and durability experiments were performed on HMA and WMA mixtures, involving Marshall stability, Marshall quotient, static indirect tensile strength at 25 and 60°C, and tensile stiffness modulus at 25 and 60°C. Calculating the tensile strength ratio (TSR) to study the moisture susceptibility of the mixes was used to assess their durability. The study indicates that compaction efforts had a considerable impact on the performance of the mixtures. The Natural Zeolite of WMA & Synthetic Zeolite of WMA mixtures display lower Marshall stability and Marshall quotient with greater tensile strength and tensile strength ratio than HMA mixture for 35, 50 and 75 compaction efforts. Increased compaction efforts result in a greater reduction in mechanical and durability characteristics of WMA. The flow values of NZWMA and SZWMA mixtures are larger than HMA mixtures indicating higher strain capacities to achieve failure. All NZWMA and SZWMA mixtures achieve the SCRB standard specifications of 8kN stability, 2-4mm flow, 14 percent VMA, and 85 percent TSR when using the same optimum binder content. Furthermore, the NZAC mixtures show higher performance than SZAC mixtures in terms of stability and strength