On the Use of Interfacial Fracture Mechanics Approaches for Evaluation of the End Movement in Concrete Slabs

Abstract

This dissertation aims to study effects of different design factors on the end movements in Continuously Reinforced Concrete (CRC) pavements subjected to environmental loads. End movement in CRC pavements is an important distress leading to deterioration of in-service pavement structures. Different models, including closed form solutions and numerical approaches for prediction of the concrete slab displacements, are introduced and discussed. The effect bond strength between the concrete slab and the subbase layer on concrete slab end movement is investigated using interfacial fracture mechanics concepts. First, the theoretical criteria describing the mechanism of interfacial crack propagation are discussed in a general framework. A modified version of the maximum tangential stress criterion is developed for strong interfaces and it is shown that the proposed model provides more accurate prediction of the experimental data. A new fracture test specimen, which covers all mixed mode conditions, is proposed for evaluation of the bond strength between two dissimilar materials. The new test specimen is then employed for evaluation of the bond strength between the asphalt concrete and the Portland cement concrete.

As the next step, a series of three dimensional finite element simulations are performed to investigate end movements in CRC pavements. The concrete slab/ subbase layer and concrete slab/ reinforcing steel bar interfaces were modelled using a zero thickness cohesive layer which follows traction-separation constitutive law. The results of the finite element simulations are compared with those measured from experiments by previous researchers. Finally, the effects of CRC dimensions, material properties, bond strength, and environmental loads on the end movements in CRC pavements are explored using three dimensional finite element simulations. The results obtained in the present work can help pavement engineers to better understand the mechanism of end movements in CRC pavements.