Analysing a pavement structure with a crushed stone overlaying on an existing thick asphalt layer

Abstract

It is a rare practice in South Africa’s engineering industry to keep the existing asphalt intact and to construct a granular subbase and / or base above it. This study investigates such a pavement structure in order to gain a better understanding of how it functions. Therefore, the influence of slippage between a granular layer on top of an older asphalt layer was determined as well as the structural capacity of the pavement which was then compared to more conventional pavement structures. Also, possible economic benefits were identified. A case study (N1 Section 17) was selected for investigation. Theoretical models were evaluated using Linear Elastic Analysis (LEA) for various slip conditions and scenarios. The elastic surface deflections were calculated for various slip rates and the results showed that the surface deflection increased exponentially as the slip rate increased. Both the LEA and Finite Element Analysis (FEA) calculations indicated that the bearing capacity of the pavement structures evaluated was sensitive to slippage between the base and the older asphalt layer. This study consequently found the inverted pavement structure to be a viable construction option within the limits of this study.