Experimental measurement of load-transfer length in textile-reinforced cementitious matrix composites using distributed optical fibres

Abstract

This paper discusses a micromechanical parameter that governs the behaviour of textile-reinforced cementitious matrix composites (TRCMCs) under tensile load: load-transfer length. This parameter determines the number, location, and spacing of cracks in TRCMCs, and it depends on the interaction between the textile and the matrix. The objective of this study was to experimentally measure the load-transfer length of TRCMCs during a tensile test. For this purpose, optical fibres (as strain sensors based on the Rayleigh backscattering principle) were embedded in the core of TRCMCs at different positions, allowing precise measurement of the strain in the matrix and the textile reinforcement before, during, and after the occurrence of cracks. Nine TRCMCs were tested in this study: two types of matrices, two types of textile reinforcement and three reinforcement ratios. The development of the load-transfer length during the test was identified, measured, and analysed. The effects of the matrix type, textile type, reinforcement ratio, and crack distribution on the load-transfer length were examined. The mechanical behaviour of the textile/matrix interface after the cracking of the TRCMCs was investigated. These results allowed the analysis of the cracking mechanisms and elucidated the mechanical behaviour of the crack-propagation zone of TRCMCs under tensile load. Highlights Measurement of the load-transfer length of textile-reinforced cementitious matrix composites; Identification of the type of mechanical behaviour of the textile/matrix interface; Effect of the energy dissipated by the interface damage on the development of the load-transfer length; Effects of crack history and positions on the load-transfer length; Effect of the reinforcement ratio and matrix type on the evolution of the load-transfer length.