Topographical analysis of fractured surface roughness of macro fiber reinforced concrete and its correlation with flexural toughness

Abstract

Macro fibers reinforcement is considered to be an effective way to improve the flexural toughness of the concrete. With growing public interest in the wide-spread use of fiber reinforced concrete (FRC), the need for understanding and evaluating micro fiber reinforcement mechanism is on the rise. In this study, concretes were reinforced by various dopant amounts of macro polypropylene (PP) fiber or steel fiber (SF) or their mixtures, topographical analysis was applied on a fractured concrete surface by using a custom-built 3-D laser scanning equipment, and the tested surface was fractured by using a three-point bending beam test. The topographical analysis results were evaluated quantitatively by roughness parameters of roughness number (RN), fractal dimension (D), standard deviation of height distribution (σz), and arithmetic mean deviation of the surface topography (Ha). Multivariate analysis suggests the most effective of roughness number (RN) for evaluating the roughness of fractured surface. Furthermore, the RN of fractured surface was further correlated to the flexural toughness of the concrete, the relation between the fractured concrete surface roughness (RN) and flexural toughness follows an exponential function, which can be employed to quickly estimate its roughness of fractured surface by flexural toughness of the FRC. In conclusion, from the developed topographical analysis method, the hybrid fibers reinforced concrete shows the most significant improvement of the flexural toughness of the concrete, which suggests hybrid fiber reinforcement shall be a future solution for commercialization of the FRC in terms of high toughness and high durability.