Evaluation of microstructural properties in sand–sulphur–bitumen (SSB) mixes

Abstract

The sand–sulphur–bitumen (SSB) mixes may prove to be a promising solution for locations where sands are available in plenty while natural stone resources are scanty. This paper is an attempt to study the microstructural characteristics of SSB mixes which normally have much higher air void content as compared with the conventional bituminous mixes. In this paper, the air void characteristics of SSB mixes were studied with the help of X-Ray micro computed tomography coupled with high-end image processing tools. Two methods namely flux-based algorithm and pore centroid method were implemented for the determination of tortuosity, which is linked to microstructural characteristics of the mixes. An expression for the prediction of tortuosity was developed to establish a relationship between various air void characteristics and tortuosity. Seventeen different types of SSB mix specimens having variable air void contents were prepared and their air void characteristics were considered for model development using Artificial Neural Network. Sensitivity analysis of the resulting model indicated the significance of each microstructural property related to tortuosity. It was observed that the connected air voids and specific surface have significant influences on tortuosity of the SSB mixes.