In situ measurement of coefficient of thermal expansion in hardening concrete and its effect on thermal stress development

It is well known that the coefficient of thermal expansion (CTE) has substantial effects on behavior and performance of concrete structures. In this study, a time-dependent variation of CTE in hardening concrete was examined based on a series of field experiments using a device called impervious non-stress cylinder (INC). The results showed consistent trends: (1) the CTE at the time of setting is about twice as high as the CTE in the stabilized stage and (2) after the CTE's initial sudden drop, it starts to slightly increase for a certain period of time and then stabilizes. The present study also quantitatively investigated the effect of time-dependent CTE variation on thermal stress developments. The results revealed that the effect of CTE's time-dependent variation is non-negligible; rather, it may be of great importance for accurate assessments of early-age cracking potential and the later-age behavior and response of concrete structures.