Treatment of glassfibre strands in polymer and silica fume dispersions to improve the ageing performance of glassfibre-reinforced cements

Synopsis Glassfibre strands were immersed in polymer latex or silica fume dispersions before incorporating them in a cement matrix, in order to improve the ageing performance of the composite. These treatments always enhanced the performance, their effectiveness depending on the type of dispersion and fibre. In composites reinforced with alkali-resistant (AR) glass fibres, both dispersions were equally effective in eliminating almost any loss in strength during accelerated ageing, but the silica fume treatment was more effective in limiting the loss in toughness. The treatment of E glass fibres with polymer latex enhanced the ageing performance to levels better than those of untreated AR glassfibre reinforced composites, although the polymer did not completely eliminate chemical attack of the E glass. The influence of the two treatments is discussed in terms of their effectiveness in providing a barrier to chemical attack and their ability to preserve the flexibility of the reinforcing strands by slowing down or preventing enhanced fibre-matrix bond due to growth of hydration products around the filaments in the strand.