Properties of cement composites reinforced with Kevlar fibres

The organic polyamide fibre, Kevlar, is promising as an efficient reinforcement for cementitious matrices. For cement boards, in which chopped fibres are distributed randomly in two dimensions, typical mechanical properties obtained with 1.9 vol% fibre addition are as follows: ultimate tensile strength (UTS) 16 MN m^–2; MOR 44 MIN m^–2; impact strength 17 kJ m^–2. The composite material can be produced by autoclaving if desired and at ambient temperatures they are expected to be durable in most environments. The relatively low decomposition point of Kevlar (as opposed to glass fibres or steel) is a disadvantage for its use in building components which may come into contact with high temperatures, as in a fire. It should be noted that a solvent which is used in the manufacture of the fibre and remains in the fibre in minute quantities has been found to produce cancer in rats. There is no evidence of it causing cancer in humans but the significance of this in terms of a possible health risk, if any, will need to be assessed by the appropriate medical authorities in relation to any applications.