Effects of Concrete Stiffness on Mechanistic-Empirical Performance of Unbonded Jointed Plain Concrete Overlay

Rehabilitation of existing jointed plain concrete pavements (JPCP) by using unbonded jointed plain concrete overlay is increasingly being used all over United States. The design and performance of un-bonded overlays is affected by various factors including climate, traffic volume, concrete material properties, existing pavement condition and future design life. Modulus of elasticity/stiffness of concrete is an important material property that has significant effects on the performance of concrete pavements and many researchers have acknowledged it. But there has not been much research on effects of elastic modulus on performance of unbonded overlays. This study focuses on the impact of variability of elastic modulus of concrete on the mechanistic-empirical performance predictions of un-bonded JPCP overlays. Simulations were conducted using pavement ME design software with varying elastic modulus values and keeping all other design factors as constant. The results indicated that with decrease in elastic modulus values, the performance of un-bonded JPCP overlay is adversely affected with increased transverse cracking. The adverse effects of lower elastic modulus can be compensated by increasing the thickness of overlay concrete slab or by decreasing the transverse joint spacing and obtaining improved overlay performance.