Selection of asphalt mix with optimal fracture properties at intermediate temperature using Taguchi method for design of experiment

Abstract

Fracture properties of asphalt mix at intermediate temperatures can be related to its resistance to cracking associated mainly by repetitive loading (i.e., fatigue cracks). These properties can be directly related to the properties of mix ingredient and asphalt mix design. In this paper, Taguchi experimental design and analysis was examined to achieve an asphalt mix with desired fracture properties at intermediate temperature. Reducing the number of experiments required, considering the target value variability in evaluating, analyzing and predicting of data and considering the interaction between factors in the analysis of results are the main advantages of Taguchi method. Through this approach the effect of aggregate gradation, asphalt binder content and type, and filler content and type were evaluated. For aggregate gradation two levels and for other factors three levels were considered in the experimental plan. The maximum load to fracture and the fracture energy obtained by SCB test at 25 °C were selected as fracture properties that can be indicator of mix cracking resistance. Generally, it has been revealed that Taguchi method with well approximation can predict optimum mix behavior and can potentially be used for the performance-related design of asphalt mixes. The results showed that among the mix design factors that was used, asphalt binder content has the greatest effect on the asphalt mix fracture strength and energy. The next important factors are successively the filler type, the filler content, the aggregate gradation, the asphalt binder type, and finally the aggregate type.