Alkali Resistant (AR) Fiberglass Roving are designed specifically for use in concrete. They are manufactured from a specially formulated glass composition with an optimum level of Zirconia (ZrO2) to be suitable for use in concrete. AR Glass Fibers are particularly suitable for Premix GFRC and other mortar and concrete reinforcement applications. They have high tensile strength and modulus, do not rust like steel, and are easily incorporated into concrete mixes.