Thermal strain and drying shrinkage of concrete structures in the field

When concrete structures are placed in the field, substantial changes in temperature and moisture can occur. To predict stress and the corresponding risks of thermal and/or drying shrinkage cracking, an estimate is required of thermal strain and drying shrinkage not related to stress. In this study, a proposed method was developed to allow the direct field measurement of thermal strain and drying shrinkage in concrete structures. A nonstress cylinder was designed, which enabled the embedded strain gauge to measure actual thermal strain and drying shrinkage in concrete structures. Sensors, such as vibrating wire strain gauges and temperature and relative humidity (RH) sensors, were incorporated into the developed method. The validity of the method was investigated through laboratory tests as well as field implementation. It is expected that the proposed method can be efficiently used infield testing and allow realistic assessments of time-dependent behavior of concrete structures, including cracking potential.