Micromechanical analysis of concrete and reinforcing steel exposed to high temperature

This study discusses determination of macroscale properties of concrete and reinforcing steel from micromechanical properties (elastic modulus) of individual phases in concrete (coarse aggregate, mortar), and reinforcing steel that have been exposed to high temperature through micro-indentation of their respective samples. Micro-indentation results are obtained by performing grid indentation. These results are then statistically analyzed through a deconvolution technique and a self-consistent homogenization scheme, to obtain the mechanical properties at macroscale. These obtained properties from samples are useful in assessing the nature and extent of damage that has taken place in concrete or steel due to high temperature expressed in terms of stiffness reduction. As a consequence this can provide a basis for designing a suitable structural repair with an understanding of the force flow in the element. Micro-indentation of concrete samples in hot state has also been undertaken, and these results suggest that combined thermos-mechanical loads result in more degradation of concrete due to thermo-mechanical coupling. Results of elastic modulus obtained from homogenization of micro-indentation data and the elastic modulus obtained from macroscale tests are in good agreement.