Super-critical carbonation of glass-fibre reinforced cement. Part 1: mechanical testing and chemical analysis

Abstract The deterioration of glass-fibre reinforced cement (GRC) arises to a substantial extent from the alkalinity and calcium hydroxide content of the matrix. Carbonation of the matrix significantly lowers both factors, but under normal circumstances the reaction proceeds too slowly to be of practical use in improving durability. If carbonation is effected using supercritical carbon dioxide the reaction can be completed within hours rather than years, rendering it potentially attractive as a treatment for enhancing the durability of GRC. The efficacy of such treatment is dependent on the moisture content of the samples prior to treatment. GRC samples thus treated, with various moisture contents, were mechanically tested before and after a period of accelerated ageing. The supercritical carbonation treatment significantly increased the design strength and toughness of the GRC and greatly increased the fibre–matrix bond. Retention of toughness and degree of carbonation were both correlated with pre-treatment moisture content while initial property enhancements were not.