Abstract: Concrete containing limestone blended cement or blended cement with limestone and fly ash have noticeably different thermal properties. Maximum temperature rise due to cement hydration plays an important role on delayed ettringite formation and thermal cracking of the concrete. However, the maximum temperature rise due to cement hydration in the mass concrete floor would be different from thin slabs. The purpose of this study is to provide such difference for concrete with limestone blended cement and fly ash type C. In this study, results of thermocouple measurement at a new construction laboratory are compared via a 1.22m thick mass concrete floor and a 0.18m thin slab at the edge and center point of the foundation. The mass floor includes the virtical steel anchors which conduct the generated hydration heat to the bottom and surface of the slab. The results show that hydration heat is accumulated at the middle of the mass floor. Also, temperature profile of the thin slab and bottom heat flux records mostly follow the ambient temperature. In addition, the bottom of the mass floor is affected by hydration heat conducted by vertical steel.