Impact of Curing On the Strength and Mechanical Properties of Cold Mix Asphalt

Abstract

The objective of this study was to assess the impact of curing on the strength and mechanical properties of Cold Mix Asphalt (CMA). While curing is critical for moisture dissipation and the development of adhesive bonding between residual bitumen and aggregates, the uncertainty of this evolution often limits the structural use of CMA. This research investigated the influence of curing temperature (25 and 38 oC) and duration (7 and 14 days) on control mix (CM) and cement-stone dust (CS) mixes. At first, the strength of CMA was evaluated through Indirect Tensile Strength (ITS), while the mechanical property was evaluated using Resilient Modulus (MR). The test findings indicated that curing conditioning significantly influences the strength and mechanical properties of CMA mixes. Furthermore, the indirect tensile strength (ITS) increased with higher curing temperatures, particularly in cement-modified mixes. Next, the resilient modulus of the CMA mix was determined, and it showed significant improvement with the addition of cement. The statistical analysis revealed that for the strength property, except for curing duration, other factors, such as curing temperature and mix type, had a significant impact. Whereas, for mechanical properties, the mix type, curing duration, and test temperature had a significant impact, particularly for cement-modified mixes. Although the cement-modified mix exhibited higher stiffness values, the CS mix's higher resilient modulus cannot be considered a true indicator of structural strength, as its high brittleness may lead to sudden fatigue failure under heavy traffic conditions. It is recommended to conduct comprehensive performance testing, including rutting and fatigue-life analysis, to verify the suitability of the cement-modified mix as a structural layer. It is envisaged that the study findings will offer valuable insights related to the strength evolution of CMA and thus help promote the utilization of CMA in flexible pavement.