Abstract
In this paper, we investigated quality properties for the expansive of the CaO-$CaSO_4$ family which used to compensate dry-shrinkage in the floor mortar of On-Dol heating System. This experimental study established the mix condition with quantity of the expansive and is to investigate the relativity between the compress strength and the length change and the relativity between the chemical properties and the length change with the analysis of the physical and chemical properties. As a result of the study, the expansive is controlled by more the CaO than the $CaSO_4$. The relativity between the compress strength and the length change is expressed by exponential function, showing that if the expansive performance is increased, the compress strength is decreased. And the relativity between the chemical properties and the length change is only relative the quantity of the F-CaO among the chemical properties, is expressed by the second order function, showing that if the F-CaO is increased, the expansive performance is increased.
