Predicting fatigue damage growth in cement-treated base layer built with construction and demolition waste

Abstract

Fatigue damages of cement-treated construction and demolition waste (CDW) aggregate base materials were predicted using a nonlinear elastic-damage model coupled with a finite element (FE) program. CDW with two different gradations (BC1 and BC2) and one control cement-treated base material using quarried aggregate (N1) were tested. Three-point bending strength and fatigue tests were conducted to obtain the fracture property of the three base materials and inputs of the proposed nonlinear elastic-damage model. Pavement structures with the three base layers were modelled by FE simulations, to evaluate the mechanical and cracking performance under three different vehicle load levels of 700 kPa, 840 kPa and 1050 kPa, respectively. The result of experiments shows that the BC1 with a skeleton-dense gradation has the highest fracture strength, which was followed by the N1, and is much higher than the BC2. In the FE simulations, the proposed nonlinear elastic-damage model can well reflect the damage evolution and modulus distribution of cement-treated base layers under vehicle loading. With the accumulation of vehicle loading cycles, the damage of base layers increases, and pavement structure with the BC2 base layer shows the fastest damage evolution. Besides, the stress-dependent modulus shows a non-uniform distribution in the base layers, presenting very high values at the surface and bottom of the base layer due to the high compressive stress and tensile stresses.