Preparation and properties of new type low-temperature early strength accelerator

The traditional early strength components have not met the requirements of green and high performance concrete, especially in the long-term mechanical properties and durability. The low temperature early strength performance of the existing early strength accelerators is relatively limited, and the research on the mechanism of early strength or that on its influence on concrete durability is also insufficient. In our research, a new type of low-temperature early strength accelerator, which has no alkali, no chlorine and no sulfate ions, was prepared by using four components of inorganic salt CB, LB, triisopropanolamine and nano-SiO₂, and its early strength performance and adaptability were also analyzed. The results show that the effects of the early strength accelerator with the optimal ratio of 0.50% CB+1.00% TIPA+0.20% nano-SiO₂+0.30% LB is highly reliable. CB and LB were the key components, which played an important role in improving the strength of mortars at different ages under low temperature curing, and TIPA had a significant effect on the strength enhancement after 3 d, while nano-SiO₂ was beneficial to the strength improvement after 7 d. At 5 ℃, the 1 d, 3 d, 7 d and 28 d compressive strengths of the motars mixed with early strength accelerators could be increased by 377%, 98%, 72% and 18% respectively, and the strength development of mortars after 3 d had exceeded the strength development of the contrast samples cured at 20 ℃. Low-temperature early strength accelerator had good adaptability to different types of cement and temperature.