Enhancing the thermo-mechanical properties of calcium aluminate concrete at elevated temperatures using synergistic flame-retardant polymer fibres

Abstract

This paper presents a systematic study on the feasibility of using synergistic flame-retardant polymer (SFRP) fibres for enhancing thermo-mechanical properties of calcium aluminate concrete at elevated temperatures. A series of tests were conducted to investigate the effect of SFRP fibres and cement type on thermal conductivity, compressive, splitting and flexural behaviours, and microstructural and micromechanical evolutions of concrete at different temperature levels, based on which the underlying mechanisms for enhancing the thermo-mechanical properties of calcium aluminate concrete were explored. Experimental results indicate that the combined usage of calcium aluminate blinders and SFRP fibres can significantly promote the strength-sustaining capacity (e.g., less than 45% compressive strength loss at 800 °C) and effectively prevent explosive spalling of concrete. The underlying mechanisms for enhanced thermo-mechanical properties of concrete can be explained by (i) the further reaction between hydration products and pozzolanic materials, which reduces the strength loss of concrete, and (ii) the melting, foaming and overflowing of SFRP fibres, which improves the connectivity of pore network and lowers the conductivity of concrete, and thereby improves the permeability and slows down the mechanical degradation of concrete.