Temporal and Spatial Variation in Drying Shrinkage and Thermal Response of a Jointed Plain Concrete Pavement

Abstract

Drying shrinkage and coefficient of thermal expansion (CTE) are key material properties that affect the long-term performance of a concrete pavement. The importance of these two properties will continue to increase as extreme heat events occur more frequently with climate change. Standard laboratory tests performed to quantify these properties do not replicate the in-situ slab conditions such as spatial and temporal variation in moisture levels. As a result, laboratory-determined material property values may not accurately reflect the response of the pavement to changes in temperature. In this research, strain data from a 16-year-old in-service jointed plain concrete pavement was studied with a focus on the variation in drying shrinkage and response to temperature change. Drying shrinkage over time was estimated at different locations within the slab. Additionally, the structural coefficient of thermal expansion (SCTE) was determined as the strain response of the slab to unit changes in temperature. The frequency and amount of monthly rainfall was compared with SCTE results to explain seasonal variation in SCTE values. The results indicate that slab restraint conditions affect both the development of drying shrinkage and the SCTE of the pavement. Additionally, this study shows that both drying shrinkage and SCTE are not constant through the pavement structure, and both parameters are affected by the moisture content of the concrete. The SCTE was up to 23% larger and 22% smaller than the CTE determined through laboratory testing. In addition, only 31% of the laboratory measured ultimate drying shrinkage was realized in the slab.