Influence of transport properties on the determination of conditioning and thickness to obtain uniformly damaged FRC specimens

A conventional flexural beam test subjected to environmental conditioning, especially cyclic wetting and drying, results in a non-uniformly damaged specimen at the cross section as well as non-uniform stress distributions. Some limitations for durability evaluation can cause an erroneous behavior of fiber pull-out. To obtain a uniform stress distribution at the failure surface with minimized thickness, this paper evaluated transport properties affecting the movement of deleterious materials into FRC. The most common fiber types and volume fractions used in industry were chosen with input from the manufacturers. Steel fiber at 1%, PP fiber at 0.5%, and PVA fiber at 0.75% were used. The absorption test by capillary action was identified as the critical transport mechanism to produce an effective cyclic wetting conditioning and uniformly damaged specimen. It was found that a 7-day conditioning cycle and 25 mm thickness were appropriate to maximize the transport of the harmful materials with a minimized conditioning period.