The relations between autogeneous shrinkage and hydration of cement pastes prepared with low heat cements and ordinary portland cement were studied. Two types of turning point which was not recognized in the chemical shrinkage curve was recognized in the autogeneous shrinkage curve. Time to first turning point was related to setting time of cement used. Second turning point was observed when gypsum was consumed. Low heat cement pastes expanded from first turning point to second turning point. This expansion was attributed to the formation of ettringite. It was suggested that shrinkage after second turning point was initiated with the morphological change of ettringite crystal.
