Influence of CBR value in embankment materials on the improvement of recycled asphalt concrete pavement

Abstract

Reclaimed Asphalt Pavement (RAP) is the by-product of removing old asphalt concrete pavements through milling or excavation and broadly improves the engineering properties by mixing RAP with crushed rock and cement or polymer called “pavement in-place recycling”. The cost of raw materials can be significantly decreased and the mixing process easier
if cement or polymer is neglected. A road structure typically consists of multiple layers which the California Bearing Ratio (CBR) of the soil in each layer is different. This research studies the influence of CBR value in soils to improve the engineering properties of RAP. A different type of soil especially for road embankment includes gradation and CBR mixed with RAP in several ratios by weight were compacted and the CBR values evaluated to determine the appropriate mixing proportion. Based on the test results, native soil is found to improve the strength of RAP by densification and the maximum CBR of mixed material increased due to larger amounts of CBR in the native soil. However, the maximum CBR of mixed material after the appropriate mix proportion point is constant and cannot exceed the native soil. While ARP increases the CBR, it also reduces the percent of swilling for soaked condition. The cost of raw materials
is reduced because RAP performs a rigid body filled soil mass up to increase volume. Finally, this research also presents a cost-benefit analysis in which the cost of different layers of road structure are compared.