The performance of High Performance Reinforced Cement Based Composites (HPFRC) before reaching the elastic limit is governed by microcracking. For the purpose of enhancing serviceability, durability and transport properties (e.g. permeability) there is a high interest on how fibers can control cracks in the micron range. It has been reported that fibers reduce permeability of separation cracks in fiber reinforced concrete and are beneficial to its durability. Fibers reduce the cracking tendency, confine the crack width and thus reduce the permeability of cracked concrete. The goal of the research presented here was to study the effect of steel fibers on cracking and permeability of HPFRC and to support accounting for permeability and cracking resistance besides strength, as criteria to be considered in mix design in order to achieve a durable composite. In me current study, factors which may influence the relationship between crack width and permeability like fiber volume and the average width of the crack were examined. A feedback-controlled wedge splitting test was used to generate width-controlled cracks and speckle interferometry was used to record the cracking history. Water permeability of the cracked composite was then evaluated by a low-pressure water permeability test. cracked rocks with parallel walls.
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