Microstructural and mechanical behaviour of polyamide fibre-reinforced plaster composites

Different concentrations of polyamide fibres with given aspect ratios were associated to a commercial plaster in a view to investigate the mechanical behaviour. The presence of these water-absorbent fibres perturbs the hydration of the plaster and causes changes in the plaster microstructure. All the mechanical parameters decrease monotonically as the concentration of fibres is increased, except the fracture toughness which shows a different trend. The ability of the composites to retain strength at the onset of matrix cracking has been forecast and analysed on a phenomenological basis in terms of a fibre efficiency factor which is a useful supplement to the usual mechanical characterisation of such materials.