Crack crack prevention manner null of reinforced concrete manufacture at time of hot

摘要

PURPOSE:To remarkably decrease the tensile stress generated in a concrete by the thermal expansion difference between reinforcing steel and concrete in high-temperature curing, by using an expanding agent in the mixing step of concrete, thereby restricting the range of residual expansion ratio of concrete defined by a specific formula. CONSTITUTION:An expanding agent is used in the mixing stage of concrete in an amount to give a residual expansion ratio of concrete of 10-30% calculated by the formula (A-B)/BX100 (A is expansion ratio of concrete at the end of the curing with normal pressure steam; B is expansion ratio of concrete at the end of the curing with steam of high temperature and pressure). The curing conditions with normal-pressure steam are the maximum heating temperature of 45-65 deg.C, the period to keep the highest temperature of 1-9hr and the maturality of 300-500 deg.C.hr in the case of using a lime-based expanding agent and the maximum heating temperature of 55-65 deg.C, the period to keep the highest temperature of 1-9hr and the maturality of 400-500 deg.C.hr in the case of using a calcium sulfoaluminate-based expanding agent.