Micromechanics based multi-level model for predicting the coefficients of thermal expansion of hybrid fiber reinforced concrete

Abstract

This study is involved with presenting a multi-level micromechanical model for predicting the coefficients of thermal expansion (CTE) of randomly distributed and oriented short hybrid fiber reinforced concrete (HFRC), which includes the cement paste level, concrete level, and HFRC level. In this micromechanical model, the inner products (IP), outer products (OP), calcium hydroxide (CH), unhydrated clinker, sands, aggregates and hybrid fibers are comprehensively considered. A substepping homogenization framework is presented to realize the upscaling from the microstructure to macro HFRC, based on which the overall CTE of HFRC is determined. In addition, the volume fractions of phases at each level are also presented to facilitate the prediction of CTE. Comparisons with experimental data from previous studies are implemented level by level. Subsequently, the influences of the water-cement ratio, the hydration degree, the aggregate property and the fiber property on the CTE are discussed carefully.