Test study on hydration temperature of compound concrete made of demolished concrete lumps and fresh concrete

Twelve 300 mm cubes and four 1000 mm cubes made of demolished concrete lumps (DCLs) and fresh self-compacting concrete (FSCC) were manufactured, and hydration temperatures of these cubes were measured during the first seven days after casting. The influence of replacement ratio of DCLs (0, 20%, 25%, and 30%) on hydration temperature of the compound concrete containing DCLs is examined. It is found that the using of DCLs is an effective way to reduce the hydration temperature in concrete mix, and such temperature decreases gradually with the increasing of the replacement ratio; the maximum hydration temperature of the 1000 mm cube with a replacement ratio of 30% is only 84.5% of that of the 1000 mm cube made of FSCC alone.