Comparative Toughness Testing of Fiber Reinforced Concrete

Abstract

Round-robin tests of the flexural toughness of fiber reinforced concrete were conducted using six different testing machines in five different laboratories. Six groups of beams, including a plain concrete control, two different volumes of polypropylene fibers, and three different volumes of steel fibers were tested in accordance with American Society for Testing and Materials (ASTM) C1018, with special care taken to exclude the "extraneous" deflections due to deformations at the specimen supports. The results from laboratory tests were used to compute the ASTM C1018 toughness indices and the corresponding residual strength factors. Also, the Japan Society of Civil Engineers (JSCE) Toughness and Toughness Factor were calculated. The findings suggest that although the load versus deflection curves were naturally quite variable, in most cases there was no significant difference amongst the participating laboratories, except for those mixes with a very low toughness. In addition, ASTM C1018 toughness indices did not discriminate very well amongst the different fiber contents or different fiber types; the JSCE parameters were more successful in this regard.