Reaction-degree-based multi-scale predictions for the effective properties of ultra-high-performance concrete

Abstract

Through upscaling from the hydration products to a macroscopic composite, a multi-scale framework is proposed to predict the effective properties of ultra-high-performance concrete (UHPC) with different reaction degrees. In this framework, the hydration of Portland cement and the pozzolanic reaction of silica fume (SF) are taken into consideration. Different length scale representative volume elements are used to describe the material's hierarchical microstructures. The constituents’ volume fractions at different length scales are analytically calculated by the reaction degrees of Portland cement and SF. Multi-scale and multi-level homogenisation schemes are adopted to quantitatively relate the microstructures to the macroscopic properties. The numerical results showed that estimations of existing hydration models can be obtained as special cases of the proposed model. By comparison with experimental data and results estimated in previous work, it was found that the proposed multi-scaling approaches are capable of predicting the macroscopic behaviour of UHPC with different reaction degrees.