Debonding length in normal concrete and fiber reinforced concrete

Abstract

In this thesis work an investigation program on normal plain reinforced beams (NC) and fibre reinforced concrete (FRC) was performed. In the first part of the study several ways of investigation of the internal cracking condition of the concrete matrix were used, focussing on the debonding process, or rather the relative slip between concrete and steel. Of the investigation method proposed (Ink, NaCl, epoxy resin impregnation and epoxy injection) the efficiency and obtained results in ten bending-caused cracks in beams with the same geometry was compared. In the second part of the study a comparison between the NC and FRC was performed using the technique of the epoxy impregnation, measuring manually the debonding length with the aid of a UV light. This operation was performed in four bending-cracked beams and four beams cracked by action of shear loading. The result, mainly concerning the bending beams, showed that the measured debonding length considerately changes with dependency to the used method, and then the addition of the 0.5% steel fibres in the used concrete has a noticeable influence on it, decreasing it approximately by 30%, which may potentially increase the service life according to recent findings reported by other authors in the literature.