Effects of short-term ageing scenarios on asphalt mixtures’ fracture properties using imaging technique and response surface method

Abstract

ABSTRACT This paper evaluates the fracture properties of mixtures subjected to different short-term ageing conditions obtained from semi-circular bending test. Response Surface Method (RSM) was used to develop an experimental matrix based on the central composite design. Ageing temperature, ageing duration and duration in humidity and ultraviolet chamber were selected as short-term ageing parameters, while fracture toughness or stress intensity factor (K), broken aggregate (BA) and adhesion failure (AF) were regarded as responses. Image analysis technique was employed for quantification of failures (including adhesion and cohesion failures) on the fractured surface of mixtures. The susceptibility of mixtures’ fracture properties to temperatures was also determined in terms of KTS. The responses were analysed using RSM. The results showed that ageing temperature and ageing duration were the dominating ageing factors affect responses. Ageing increment resulted in higher K and BA while exhibited contradictory effects on AF. Test temperature increment reduced the fracture toughness. The KTS was increased at higher temperatures. Lastly, RSM and image analysis technique exhibited great reliability and capability to study the behaviour of the responses exposed to various ageing conditions.