Abstract
The paper presents an experimental study on the evaluation of the compressive strength and modulus of elasticity of ultra-high performance concrete (UHPC) prepared with varying steel fibre contents, cured in water and exposed in air, and subjected to three exposure conditions (after 28 d of curing): laboratory environment, alternate heating-cooling cycles (heating at 60 degrees C for 2 d and then cooling at room temperature for 2 d), and alternate wet-dry cycles (wetting for 2 d in aggressive salt solution and then drying at 30 degrees C for 2 d). The test results indicate that: (a) although water-curing is better than exposure in air in improving the strength, the difference is not significant, particularly at a higher fibre content, (b) an increase in the fibre content can improve the strength and modulus of elasticity up to a certain extent, but beyond that an increase in the fibre content is not proportionally beneficial and (c) the effect of 6-month exposure to wet-dry and heating-cooling cycles on the strength and modulus of elasticity is negligible; indeed, the heating-cooling cycled specimens have strength and modulus of elasticity higher than the specimens not subjected to the cyclic exposures.