Experimental Study on High-Early-Strength Precast Concrete

High-early-strength precast concrete technology can improve production efficiency and save energy. The use of early-strength type polycarboxylate water reducers can shorten the setting time of concrete and steam curing time of precast concrete and can significantly improve the early strength of concrete. Early-strength superplasticizer BTC300 bearing with sulfonic acid groups and amide groups is synthesized at room temperature and has some significant functions, such as slow release, early strength improvement, and high water reduction. The tests of preparing C30 ~ C80 precast concrete show that compared with concrete with the normal superplasticizer BTC100, concrete with early-strength type superplasticizer BTC300 have higher 1- to 3-day average strength, whether under steam curing conditions or at room temperature. The feature becomes more prominent as the strength grade increases.Also, the 28-day strength of concrete with BTC300 is slightly higher. GPC analysis shows that the active ingredients of BTC300 superplasticizer molecules are much higher and the content of small monomer polymers is low, so it has little influence on delay of cement hydration reaction. Hydration heat tests show that the second hydration exothermic peak with BTC300 is nearly 10 hours earlier than that of BTC100. These tests proved that the function of BTC300 is relatively early strengthening.