Influence of Single- and Two-Stage Aggregate Manufacturing Mechanisms on Asphalt Mixture Performance

This paper presents the effects of single-stage (jaw crusher alone) and two-stage crushing (jaw crusher followed by an impact crusher) mechanism on the mechanical properties of aggregates. A two-phase study was designed to investigate the effectiveness of two-stage crushing mechanism in improving the properties of aggregate and performance of asphalt mixtures. Aggregate packing, mechanical properties, and their influence on asphalt mixture performance have been discussed. Performance tests comprising stiffness, resistance to rutting, adhesion, and fatigue cracking were conducted in the laboratory. The study revealed that aggregate particles manufactured in a two-stage crushing process were more cubical in shape and exhibited better laboratory test results than single-stage crushing. Packing of aggregates using single-stage crushing could not be possible within the Bailey’s defined ratios. A reasonable relationship exists between the octahedral shear stress and the resilient modulus for both types of materials under a triaxial testing methodology. However, asphalt mixtures with aggregates from two-stage crushing showed relatively better results. Also, the variability in the performance parameters in the case of two-stage crushed materials was relatively less compared with single stage crushed materials.