EFFECT OF TEMPERATURE AND HUMIDITY ON FRACTURE ENERGY OF CONCRETE.

Fracture experiments were conducted at temperatures from 20 to 200 C (60 to 392 F) to determine the dependence of the Mode I fracture energy of concrete on temperature as well as the specific water content. The fracture energy values were determined by testing geometrically similar specimens of sizes in The ration 1:2:4:8 and then applying Bazant's size effect law. Three-point bend specimens and eccentric compression specimens are found to yield approximately the same fracture energies, regardless of temperature. To describe the temperature dependence of fracture energy, a recently derived simple formula based on the activation energy theory (rate process theory) is used and verified by test results. The temperature effect is determined both for concrete predried in an oven and for wet (saturated) concrete.