Characterizing Strain Induced by Environmental Loads in Jointed Plain Concrete Pavements

Abstract

The focus of this study is to provide a detailed analysis of the strain that develops as a result of environmental loads. The study characterizes slab response immediately after construction (first 72 h after paving) and also addresses seasonal effects over the first 10 months following construction. A heavily instrumented test section was constructed on SR-22 in Murrysville, Pennsylvania, to help characterize slab response to environmental loads better. Static strain and climatic data collected through the first 10 months after construction (August 2004 through June 2005) were analyzed to interpret pavement response to environmental loads as a function of location with respect to joint proximity, depth within the slab, and level of restraint applied to the slab. Many things were also learned about the strain that develops in the slab over the first 10 months after construction. The average strain in the fall was around –450 μstrain, whereas the average strain in the winter was –600 μstrain. The ambient temperatures increased during the spring and summer; this resulted in a decrease in the average strain to –250 μstrain. Thermal strain was found to be twice as high as the drying shrinkage the first winter after construction. A substantial amount of drying shrinkage occurred within the first 50 days after construction. Variations in drying shrinkage occur not only through the depth of the slab but also across the surface of the slab.