WHAT IS ALKALI RESISTANT FIBRE? Hydrating cement is strongly alkaline and a concrete matrix will rapidly degrade normal E gla ... ss fibre as used with polyester resin in GRP/FRP products. AR Glass Fibres have been specially formulated to resist this degradation by the addition of zirconia to the glass fibre composition. The European standard BS EN15422 2008 calls for a minimum Zirconia content of 16% and Fibratec fibres exceed this requirement. Check out our website www.fibratec.co.uk for further information, stockists, downloads and project references. read more