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

The deterioration of glass-fibre reinforced cement (GRC) arises to a substa ntial extent from the alkalinity and calcium hydroxide content of the matri x. Carbonation of the matrix significantly lowers both factors, but under n ormal circumstances the reaction proceeds too slowly to be of practical use in improving durability. If carbonation is effected using supercritical ca rbon dioxide the reaction can be completed within hours rather than years, rendering it potentially attractive as a treatment for enhancing the durabi lity of GRC. The efficacy of such treatment is dependent on the moisture co ntent of the samples prior to treatment. GRC samples thus treated, with var ious moisture contents, were mechanically tested before and after a period of accelerated ageing. The supercritical carbonation treatment significantl y increased the design strength and toughness of the GRC and greatly increa sed the fibre-matrix bond. Retention of toughness and degree of carbonation were both correlated with pre-treatment moisture content while initial pro perty enhancements were not. (C) 2001 Elsevier Science Ltd. All rights rese rved.