Effects of the structural composition on the performance of weathered stone gravel

Abstract

Paper presented at the 25th Annual Southern African Transport Conference 10 - 13 July 2006 "2010: Will transport infrastructure and systems be ready?", CSIR International Convention Centre, Pretoria, South Africa. ABSTRACT: The objective of this research was to evaluate the applicability of weathered stone gravels for use in rural roads and the factors influencing the structural strength of granular materials. The effects of the gradation, coarse size content, maximum size and fines content of gravel on its CBR value and shear strength were studied by using the CBR test and large-scale direct shearing test for two kinds of weathered stone gravels. The results showed that the CBR value of weathered stone gravel is influenced greatly by the fines (<0.0 75mm) content and the maximum size. The bigger the maximum size, the higher the CBR value. It was also concluded that the shear strenth of weathered stone gravel is influenced greatly by the coarse size content, with a maximum value of the percentage retained on the 4.75 mm sieve. Weathered stone gravels with high strength have higher shear strength and their C values correlate well with the content of aggregates below 0.6 mm. Finally, target values for the key influencing factors are recommended.