The microstructure and ageing of cellulose fibre reinforced cement composites cured in a normal environment

The correlations between microstructural changes after ageing and the mechanical performance of cellulose fibre reinforced cement composites were studied. Ageing conditions which promote carbonation (natural ageing and accelerated ageing in a CO₂ rich environment) result in densening of the matrix around the fibres and the petrification of the fibres, leading to an increase in strength and E-modulus. Accelerated ageing in a normal environment leads to densening of the matrix without fibre petrification, resulting in a reduction in strength. Both ageing environments led to a marked reduction in toughness. The processes leading to petrification and matrix densening are discussed with a view of explaining the changes in mechanical properties after ageing.