A NEW APPROACH TO ESTIMATE THE IN-SITU THERMAL COEFFICIENT AND DRYING SHRINKAGE FOR JOINTED CONCRETE PAVEMENT

Abstract

The current development of mechanistic-empirical pavement design methods will necessitate the need for more accurate and realistic material property input values. The Mn/ROAD project was developed and constructed to aid in the determination of those values for pavements in cold climate regions. Utilizing the first 7 years of in-situ strain and temperature data from the Mn/ROAD project, a new approach has been developed for determining the in-situ coefficient of thermal expansion and drying shrinkage of jointed concrete pavements. Correlation analysis between strain and temperature data from embedded vibrating wire strain sensors was performed for six Mn/ROAD concrete pavement test cells. The monthly variation of the in-situ coefficient of thermal expansion was found using the slope between temperature and strain data. The yearly variation in the drying shrinkage was estimated using the intercept from the temperature and strain data. The analysis concluded that the range of in-situ thermal coefficient values is similar to laboratory values reported in the literature for temperatures between –3 and 23o C, and when the concrete moisture content is not high. There was found to be a reduction in the slab strain, equivalent to 8 με/ o C, caused by the effect of slab restraint stresses in the spring and summer seasons. A reduction in the slab restraint effect caused by drying shrinkage as the pavement ages was observed. The joint closure temperature varies seasonally and is significantly affected by the moisture content and temperature of the pavement slab. Utilizing this new approach will enable researchers to better understand the seasonal and age related behavior of the coefficient of expansion and drying shrinkage values for jointed concrete pavements.