Fracture Characterization of Stone Mastic Asphalt (SMA) with Hydrated Lime Through the Semi-circular Bending Test Approach

Abstract

Hydrated lime (HL) use as an active filler is due to its ability to increase the stiffness of asphalt mixtures as well as the mechanical and physicochemical performance through improved rutting resistance, reduced aging, and enhanced moisture-induced damage resistance. However, understanding of the effects of HL on fatigue or more specifically on the fundamental fracture properties of asphalt mixtures still requires further investigation. As a result, this research study assessed the fracture toughness characteristics of stone mastic asphalt (SMA) mixtures with locally available materials and testing procedures in the UK context. SMA cores were subjected to semi-circular bending (SCB) testing. The experimental matrix comprised various factors for assessing and comparing the fracture toughness of the manufactured mixtures with 0, 1, 2, and 3% hydrated lime by weight of total mixture as well as a control without hydrated lime. These factors included the effects on the fracture of (1) testing temperatures (0, 10, and 20 °C), (2) aggregate type (granite and limestone), (3) environmental conditioning (ageing combined with moisture damage), and (4) the effects of filler type and content. From the SCB experimental results, it was found that the fracture is highly factor-dependent. 2 and 3% HL improved the fracture strength of the manufactured cores, whereas 1% exhibited relatively low or negligible effects on the fracture strength. Finally, the use of granite aggregates substantiated a superior fracture resistance with a 40% increase compared to mixtures produced with limestone.