Fracture properties of self-compacting mortar in terms of contents and high temperatures

摘要

In this research, the effects of five parameters, namely, water/cementitious materials ratio, limestone powder, high temperatures, polypropylene and steel microfibres, on the fracture energy (G_F) and critical stress intensity factor (K_(IC)) of notched self-compacting mortar beams were investigated. Four levels were assumed, using the Taguchi method, with an L_(16) orthogonal array for each parameter, and 32 mix designs were considered instead of 512. The prepared specimens were placed in a furnace and exposed to three temperature levels of 200,400 and 600℃ at a heating rate of 2℃/min. Mortar specimens were kept at each target temperature for 6 h. As a result, the fracture properties of the specimens initially improved but then decreased after exposure to temperatures above 400℃. At 200℃, the density of self-compacting mortar increased and reached a maximum value; this, in turn, increased the fracture energy and critical stress intensity factor of the specimens at this temperature, compared with those at an ambient temperature. Above this temperature, up to 600℃, increasing the temperature had destructive effects on the fracture properties. Furthermore, the reliability of the results are discussed and confirmed by using analysis of variance.