Influence of Waste Asphaltic Concrete Pavement on Compressive Strength of Cement-Stabilize Material

Abstract

The pavement recycling, which has been widely used in Thailand, is generally used to restore damaged pavement. The process of construction begins with the milling of damaged pavement. This damaged pavement materials are considered as waste with a large quantity. This article aims to illustrate the influence of asphaltic concrete volume, cement content and curing time on compressive strength of cement stabilized crushed rock and waste asphalt concrete. Results show that the maximum dry unit weight of the mixed material between crushed rock (CR) and asphalt concrete (AC) decreases with an increase in AC replacement for the same compaction energy (modified Proctor test). It is because the rubber in AC absorbs more compaction energy than the CR. The compressive strengths at 7 and 28 days of curing decrease significantly with the increase in AC replacement. The decrease in strength may be because the surface of AC is more slippery than the surface of CR. Consequently, the shear strength at the contact points between the particles of CR and AC becomes low. The compressive strength versus AC replacement relationship is approximately linear. The mixed material which used cement contents higher than 5% for all CR:AC ratios is greater than the recommendation by the Department of Highways, Thailand. This mixed material stabilized with cement is beneficial from both engineering and economic viewpoints.