Thermal cracks are the major problem as temperature increases in massive concrete structures. It is imperative to investigate the temperature rise and to find effective techniques to control the heat of hydration of massive concrete. In this research, based on a segmental model test of high rise building raft, the temperature field for the bottom, middle and top surface concrete of the raft caused by the heat of hydration were measured. Blast furnace slag cement (CEM III/A 42.5N) was used due to its lower percentage of C3A and C3S and lower surface area. The tested temperature rise curves indicated that the temperature increases quickly but diminishes gradually. The maximum temperature rise at the middle surface of the concrete reached 56oC, and the maximum temperature difference between the middle and the top surface was 15.80oC. The most extreme temperature difference between the top surface and the surrounding environmental temperature was 26.5oC. So, using slag cement controlled the heat of hydration of concrete leading to environmentally friendly concrete mixes.