Multi-scale investigation of the effect of thermal treatment on the tensile creep of ultra-high performance concrete: preliminary assessment

Abstract

The effect of thermal treatment on the tensile creep of steel-fibre reinforced, nano-engineered ultra-high performance concrete (UHPC) was examined through short-term creep testing, nanoindentation and scanning electron microscopy (SEM). UHPC thermally treated at 90%C for 48 hours prior to loading showed a decrease of 73% in the tensile creep coefficient and 77% in the specific creep at seven days as compared to companion samples subjected to ordinary curing. Nanoindentation showed an average decrease of 63% in the modulus of elasticity of bulk paste of UHPC with no thermal treatment. Also, the presence of a more porous and lower modulus zone around steel fibres in the case of non-thermally treated UHPC was evident by nanoindentation measurements and SEM. These preliminary measurements suggest that the differences in the interface zone between fibres and UHPC cementitious matrix may have a significant effect on the tensile creep performance.