Thermal Effects on Physico-Mechanical Properties of Ultra-High-Performance Fiber-Reinforced Concrete

Material characterization tests of an Ultra High Performance Fiber Reinforced Concrete (UHPFRC) were performed at various ages. A linear relationship was obtained between the mechanical properties and the degree of hydration. In parallel, the influence of curing conditions on the physico-mechanical properties and the time dependent behavior of this UHPFRC was investigated. A temperature increase accelerated the hydration process at early age and therefore improved the material’s compressive strength and the carrying capacity in four point bending tests, but at a long term, a higher temperature had inverse effects on the mechanical properties. Moreover, at a 20 °C temperature cure, the UHPFRC exhibited autogenous shrinkage at long term comparable to normal concrete. An increase of curing temperature increased the autogenous shrinkage. This effect may be due to the hydration and the self-desiccation processes which are accelerated at high temperatures.