This paper examined the influence of high temperature during the initial curing period on the durability of massive concrete. For this purpose, mortar speciments made with three types of cement and different mix proportions were cured in controlled temperature environments. The physical properties studied in this paper are compressive strength, diffusion coefficient of chloride ion, depth of carbonation and microstructure of matrix.
　It was recogized from the experiments where specimens were cured at high temperatures that mortar qualities such as long-term strength, resistance to chloride ion penetration and resistance to carbonation, tended to deteriorate in comparison with standard curing at 20°C. Accordingly, more attention should also be apid to the durability in massivbe concrete in addition to preventing thermal cracking.