Semi-circular bending setup for predicting fracture characteristics of high-strength fiber-reinforced concrete

Abstract

Semi-Circular Bending (SCB) Setup is commonly used to investigate the fracture parameters of the road materials like asphalt mixtures. This paper examines the performance of the SCB setup in extracting the fracture characteristics of high-strength fiber-reinforced concrete (HSFRC). Monofilament and fibrillated polypropylene fibers with polyolefin coatings of 19, 30, and 50 mm length were added to a high-strength concrete mixture at three volume percentages of 0.5, 1, and 1.5 %. Standard cube and cylinder specimens were initially fabricated for conventional material properties tests. Subsequently, the three-point bending test specimens, i.e., intact rectangular beam, notched beam, and SCB, were made using the same concrete mix of different fibers lengths and percentages. A total of 36 beam and SCB tests with three replications was conducted to find the fracture energy and pick load of each specimen. Results showed that selecting the shortest fibers (19 mm) of 0.5 % and 1.5 % by volume increased the elastic modulus and the splitting tensile strength by 70.5 % and 43 %, respectively. Also, increasing the fiber length and volume enhanced the fracture energy of the notched beam and SCB specimens up to 90 times and 40 times, respectively. However, increasing the volume of the fibers was more effective than using longer fibers in fracture energy increase. For these three test setups, finite element models were generated and analyzed to develop a numerical framework capable of predicting the fracture characteristics of HSFRCs with acceptable accuracy (maximum error of 4 %). The concrete damaged plasticity (CDP) model in ABAQUS software package were adopted to simulate the damage initiation and progression in concrete using the material properties from the conventional tests. Comparing the results of beam setups with SCB tests, it was found that SCB can be a reliable and economical setup to find the fracture characteristics of the HSFRCs.