Modelling the Fatigue Cracking caused by super-single and dual-tyred trucks on a flexible pavement

Abstract

Roads are the arteries through which the economy pulses, and are pivotal for the development of any nation. However, increased traffic and heavier vehicles cause much more distress to roads than ever before. Supersingle tyred trucks are considered more economical than standard dual tyred trucks though this is coupled with more road damage due to reduced contact area leading to higher road strains than conventional dual tyres. This study was carried out to compare the fatigue cracking caused by dual tyred and supersingle tyred trucks using Kenpave software. This software was used for determining the stresses and strains on a flexible pavement consisting of four layers (the HMA layer was 60mm thick, base course was 250mm, sub base of thickness 300mm and the sub grade at the bottom with infinite thickness). Results were then used in both the Marshall and MEPDG Fatigue Models. These results include the horizontal strain at the bottom of the bituminous layers (0.913µ for the supersingle tyred truck and 0.883µ for the dual tyred truck) and the resilient modulus of the HMA layer (1.964𝑀𝑃𝑎). The Marshall Method yielded a fatigue life in terms of number of standard axles as 4259 for supersingle tyred truck and 4852 for dual tyred truck. While the MEPDG Method yielded a fatigue life in terms of number of standard axles as 9539 for supersingle tyred truck and 10,889 for dual tyred truck.The ratio of the fatigue life in terms of number of standard axles of the dual tyred truck to the fatigue life in terms of number of standard axles of the supersingle tyred truck was 1.14 for both the Marshall Method and the MEPDG Model. This showed that the supersingle tyred truck would cause more fatigue damage to the flexible pavement, which is consistent with previous studies.