A complete thermo-poromechanical model for freeze-thaw modification of recycled coarse aggregate considering deterioration of each component

Abstract

Freeze-thaw modification is a novel method that improves recycled aggregates by utilizing the expansion of pore water during phase transitions. However, there is still a lack of theoretical analysis regarding each component in recycled aggregates during freeze-thaw. In this paper, we introduce the parameter of pore radius to transform the traditional 2D phase diagram into a 3D phase diagram of pore water. This transformation makes the phase transition conditions of pore water more clear to understand. It is then combined with the pore size distribution of each component in recycled aggregate to calculate the ice content and freezing pressure. To achieve a more intuitive evaluation of frost susceptibility, this paper establishes a frost vulnerability index (FVI). Based on the FVI curves of different rocks, their frost resistance is categorized into three levels. Finally, according to the FVI of recycled aggregates with diverse material properties, some recommendations are provided for the engineering application of freeze-thaw modification.