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

Authors: Victor Y. Garas, Amal R. Jayapalan, Lawrence F. Kahn, Kimberly E. Kurtis

Addresses: School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA. ' School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA. ' School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA. ' School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA

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.

Keywords: curing; fibre reinforcement; nanoindentation; thermal treatment; reactive powder concrete; tensile strength; ultra-high performance concrete; tensile creep; nanotechnology; steel fibres.

DOI: 10.1504/IJMSI.2009.028613

International Journal of Materials and Structural Integrity, 2009 Vol.3 No.2/3, pp.187 - 200

Available online: 21 Sep 2009 *

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