Lushinga, N. (2014). Effects of Vertical and Horizontal Load on Pavement Interface Shear Stress. IJERT, 3(10), 1295–1299

Pavement interlayer slipping in areas where the vehicle accelerates decelerates brakes or turns (e.g. toll gates, police check-points, and airport runways) are common in many developing countries. However conventional mechanistic empirical pavement designs do not consider the effect of horizontal shear load in their designs, rather they only consider vertical stress or normal load. This paper aims at exploring the effect of both vertical and horizontal shear load on the interface shear stress and subsequently the performance of pavements. The paper primarily two things: overloading and interface bonding state (contact state of pavement layers) on performance of pavement structures with respect to different loading conditions. Horizontal shear stress was considered as the main cause of pavement deformation in areas of constant vehicle braking. In this paper a stretch of 1km of Chengdu-Deyang Nanbu expressway in Sichuan province of China was considered. This road section was a test section with three pavement configurations as follows: semi-rigid base pavement, flexible pavement and full depth asphalt pavement. Material properties of pavement layers were represented by layer thickness, elasticity of modulus and poison ratio. BISAR multilayer elastic theory computer programme was used to compute mechanical responses of pavements. EverFE (FEM) pavement software was also used to come up with graphical representations of overloaded pavements. It was concluded that the severe pavement damage in areas where vehicles accelerates or decelerates is as a result of both overloading and braking which increases level force at vehicle braking. Overloading crushes and densifies the aggregates in asphalt concrete mixture thereby reducing the air voids. Loss of air voids on the other hand result in loss of mixture stability and rutting due to build up of pore pressure in the mixture under traffic loading resulting in loss of strength and flow.