The role of coarse aggregate point and mass strength on resistance to load in HMA

The ever-increasing traffic volumes, including increased truck traffic and higher tire pressures, are putting greater stresses on the asphalt pavements which manifest in the form of pavement distresses such as rutting and fatigue cracking. To address these issues, improvements in the hot mix asphalt (HMA) blends are being implemented. The new generation of asphalt pavements such as coarse graded Superpave mixtures, Stone Matrix Asphalt (SMA) and Porous Friction Course (PFC) rely more on stone-on-stone contact for a stronger coarse aggregate skeleton. The performance of HMA mixtures is greatly influenced by the properties of the aggregate blends such as gradation and strength; therefore they have a significant and direct effect on the performance of asphalt pavements. It is important to maximize the quality of aggregates to ensure a proper performance of roadways. Several methods are available to determine aggregate characteristics, but their relationship to field performance, aggregate structure in HMA, and traffic loading needs to be further investigated and defined. Current laboratory protocols do not correlate well with aggregate abrasion, toughness, and strength requirements during handling, construction, and service. Specifications should ensure that aggregate particles possess the necessary strengths to avoid degradation during handling, construction, and trafficking. In this report, the feasibility of determining the characteristics of the aggregates in a multifaceted way, considering the geological, geotechnical and mix design, is reported