Performance Criteria to Assess Shrinkage Cracking Tendency in Concrete Overlay

Differential shrinkage between new concrete overlay and that of old substrate concrete will trigger shrinkage (tensile) stress leading to cracking when this tensile stress development reaches tensile capacity of overlay. There are many parameters affecting the magnitude of shrinkage stress. Any criteria used to assess cracking tendency of concrete overlay caused by differential shrinkage should take into account all of the parameters involved in building up shrinkage stress. Assessment of shrinkage cracking behaviour of concrete overlay could be classified into qualitative and quantitative method. This paper reviews both methods. Current models for estimating shrinkage stress and their possible application for setting performance criteria to assess shrinkage cracking tendency in concrete overlay are discussed. Simplification of model is proposed and extension of data to improve the model is suggested.