Effects of water and bleaching on the mechanical properties of cellulose fibre cements

The mechanical properties of bleached and unbleached cellulose fibre-cement composites are studied in both dry and wet conditionS. Bleaching the fibres increases both the elastic modulus and flexural strength but reduces the specific work of fracture. Water has a dramatic adverse effect on the elastic modulus and flexural strength of the composites irrespective of whether the fibres are bleached or not. However, water increases remarkably the fracture resistance. A failure mechanism is proposed to explain these experimental results and this is supported by evidence obtained from scanning electron micrographs of fracture surfaces.