Measurement and Analysis of Early-Age Concrete Strains and Stresses

Abstract

The early-age behavior of continuously reinforced concrete pavement (CRCP) in terms of concrete strains and stresses due to environmental loading was extensively investigated. The strains measured with strain gauges in the actual CRCP cannot be used simply to calculate the concrete stresses by multiplying the elastic modulus of concrete because the measured strains include both the stress-dependent and -independent strains. In situ stress-independent strains were measured with vibrating wire gauges embedded in the modified half-cylinders developed in this study and in small beams. The total strains in the concrete were measured with vibrating wire gauges at different depths in both the longitudinal and transverse directions at the crack-induced area and the surrounding areas in several test sections. The crack width variation through the depth of the pavement was also measured with the gauges installed at the crack-induced area. The in situ coefficient of thermal expansion and drying shrinkage of concrete were successfully measured with the developed measurement devices, and these measured values were used to calculate the stress-dependent strains. The concrete stresses were then calculated from the stress-dependent strains and the calculated stresses were finally verified by comparison between the calculated stress at the instant of cracking and the measured strength.