Mechanical properties, long-term hydration heat, shrinkage behavior and crack resistance of dam concrete designed with low heat Portland (LHP) cement and fly ash

摘要

The utilization of low heat Portland (LHP) cement is considered to be one of the most effective methods to decrease the thermal stresses and cracking risk in the dam concrete. The long-term hydration heat of LHP cement paste up to 360 days and adiabatic temperature rise of four-graded LHP cement dam concrete (LHP concrete for short) with the maximal aggregate size of 120 mm at all hydration age is low. Due to the relatively high C2S content and slow hydration rate of LHP cement, LHP concrete possesses smaller autogenous and drying shrinkage at late age and consequently leads to better crack resistance than that of ordinary Portland cement (OPC) four-graded concrete. In addition, LHP cement paste has a denser pore structure than the OPC one at late age, which improves the final mechanical properties of LHP concrete. The shrinkage behavior of LHP concrete is closely associated with the fraction of pores in the range of 2.5-50 nm. "LHP cement + fly ash" combination seems to be a good means to decrease the temperature rise and improve the crack resistance of dam concrete structures. (C) 2018 Elsevier Ltd. All rights reserved.