Effect of curing humidity on the fracture properties of concrete

This study investigates the influence of curing humidity on concrete fracture properties. Concrete fracture energy, effective fracture toughness, and characteristic length were tested at five different ages using wedge splitting specimens exposed to four different relative humidity values (30%, 50%, 70% and 98%). Four environmental chambers capable of automatically controlling temperature and relative humidity were constructed. A data averaging method for companion specimens was introduced. The test results show that at the early age, fracture energy, effective fracture toughness, and characteristic length remained almost constant during drying. As time elapsed, however, the influence of curing humidity on the concrete fracture properties became increasingly pronounced; larger values of fracture energy, effective fracture toughness, and characteristic length were measured by concrete specimens kept at high humidity. The concrete fracture mode also gradually changed from ductile to brittle with curing humidity decreasing and hydration time elapsing. (C) 2018 Elsevier Ltd. All rights reserved.