Shrinkage Behaviour of Cement-Treated Crushed Rock Base in Western Australia

Abstract

Shrinkage cracking is a significant problem when using cement stabilised materials in the construction of road pavements. Reflective (upward) cracks travel from the cement stabilised base layer to the top of the asphalt surface can cause water ingress through the underlying pavement layers. This paper examines the shrinkage behaviour of cement-treated crushed rock base as applied to pavement conditions in Western Australia. The testing protocol to examine the shrinkage behaviour of the material was adapted from the cement shrinkage test in Australian Standards, AS 1012.13. The test results showed that the amount of shrinkage in the cement-treated material did not increase with additional amounts of cement. The highest shrinkage values were found for the 2% and 6% cement specimens, where shrinkage was approximately 17% greater than the lowest shrinkage value found for the 4% cement sample. Based on the results of this study, it seems that shrinkage in the samples with relatively higher cement content of 5% and 6% mainly results from loss of water during the hydration reaction process between cement and water. Shrinkage in the low cement content samples of 2% and 3% is governed by the evaporation of excess water after the hydration reaction. The 4% cement content sample demonstrated the optimum cement content when considering the lowest shrinkage values among other cement content samples and an appropriate unconfined compressive strength value.