Curling of concrete slabs on grade: experimental versus theoretical analysis

Abstract

Based on a mathematical approach, Westergaard (1926, 1927, 1943, 1948) derived formulae that predicted the state of stresses and strains in concrete slabs on grade subjected to temperature variations. Although Westergaard made various assumptions, his approach remained a basic tool for the design of concrete pavements. This paper presents a close experimental examination of the deformation of concrete pavement slabs subjected to temperature variations. Full-scale instrumented slabs provided data from key-performance parameters within the scope of a long-term monitoring program where concrete pavement slabs equipped with over 200 sensors are subjected to weather conditions in the absence of traffic loading. A quantitative validation of Westergaard's predictions is presented and a modification to Westergaard's curling strain formula is suggested based on temperature profiles recorded across the slab cross section. Time histories of temperature profiles showed a temperature change at the mid-slab thickness accompanied by a gradient profile (in contradiction of Westergaard's assumption). The measured response and data analysis are further verified through a three dimensional finite element study.