On the behaviour of FRCM fibres in saturated alkaline solution

The main objective of this work was to study the behaviour of fibre grids, usually employed in FRCM (Fibre Reinforced Cementitious Matrices) systems, when exposed to an alkaline solution. Three basalt and a glass fibre textiles were conditioned in a saturated solution of calcium hydroxide and distilled water at 23°C. The total exposure time was chosen equal to 1000h. To monitor the conditioning process, alkalinity levels were periodically controlled for the whole exposure time. Subsequently, tensile tests were conducted on textile samples, including multiple longitudinal strands. A series of preliminary SEM (Scanning Electron Microscopy) analyses was also conducted to verify the integrity of the organic coating applied to the fibres. The coating, indeed, has the fundamental role of preventing or delaying the degradation process. The obtained results are discussed in terms of ultimate strength and elastic modulus reductions, showing significant detrimental effects of the alkaline environment especially for the basalt fibres.