Many researchers have attempted to use mixed fibres to produce a synergy of mechanical properties, processing properties and/or cost, often driven by the desire to move to automated production. Popular hybrids include glass/carbon, steel/polypropylene and glass/polypropylene. However, few have explicitly addressed any durability issues that might be raised by using hybrids. Xu et al. (1998) reported the results of 6-year weathering on polypropylene/glass-frc sheets but no significant degradation in mechanical properties was observed. Banthia and Nandakumar (2003) have discussed the durability potential of polypropylene/steel-frc but did not present any long-term results. It seems that there are no durability synergies that can be obtained from hybrid fibre rein- forcement. The durability of hybrid-frc is therefore controlled by the time- dependent behaviour of the least durable fibre and durability analysis of such composites must focus on the extent to which any mechanical synergy can be retained as the least durable reinforcement degrades.
