A Framework to Assess Early Concrete Slab Cracking

This research was based on the findings from a field study of slab placements representing different combinations of curing conditions and placement times. One of the key objectives was to collect data with respect to slab setting characteristics as a function of the quality of curing provided for each slab. The set is referred to herein terms of a gradient that forms due to environmental effects on temperature and moisture profile variations during the initial days after placement. These profile variations effect the degree of slab support. In other words, early-age concrete temperature and moisture history is a key factor affecting the set gradient, as well as a factor in slab curling and warping behavior (corner displacement). There is also a strain profile associated with the set gradient creating a level of stress that can be related to the development of early-age cracking similar to slab curling and warping. This early-aged behavior is mostly drying shrinkage driven, and is often manifested by the separation of the slab from the substrate along the edges and the corners of the slab. This paper mainly focuses on a framework to relate early-age slab damage to the probability of slab cracking later in the performance cycle. This relationship is elaborated with respect to curing quality and its effect on the development of the set gradient as well as its role in PavementME calibration results. The PavementME developers were aware that construction weather conditions affect concrete pavement performance via the inclusion of a set gradient in the computations.