Thermal expansion coefficient of concrete at very early ages

The thermal expansion coefficient of concrete has a crucial effect on the thermal stress development. Since the thermal expansion coefficient drastically changes at early ages, it should be accurately evaluated and incorporated in the analysis. In this study, the thermal expansion coefficient of concrete was measured during the early stages of hardening by means of non-contact high-precision displacement meters (gap sensors) and embedded strain gages. The performances of the two measuring techniques were compared in order to investigate their applicability. Measurements using gap sensors proved to be valuable for elucidating the changes in the thermal expansion coefficient of early age concrete during the hardening, as well as the effect of different cement types.