Investigation of the flexural behavior of self-consolidating mortars reinforced with net warp-knitted spacer fabrics

Abstract

This work intended to study the flexural properties of self-consolidating mortars (SCM) reinforced with net warp-knitted spacer fabrics (WKSF). The effects of fabric structural parameters namely mesh size, the position of the meshes in the outer layers with respect to each other, and the fabric thickness on the properties of the composite materials were investigated. The uniaxial tensile tests were conducted to evaluate the influence of the fabric variables on the fabric elastic modulus. The cement-based specimens were made by casting in three forms: 1) plain SCM as the control specimen, 2) SCM reinforced with two 2D fabrics, and 3) SCM reinforced with the 3D spacer fabrics. Three-point bending tests were carried out. The mode of fracture was investigated through microscopic analysis using a Scanning Electron Microscope. Furthermore, the condition of the prepared SCM from porosity viewpoint was evaluated using the water absorption test with and without fabric inclusion. The tensile tests indicated that the modulus of fabrics in the wale direction is more than the modulus in the course direction. Fabrics with larger mesh and also thicker fabrics have lower modulus than the fabrics with smaller meshes and lower thickness. The fabric modulus was independent of the position of the meshes. The experimental results of the flexural tests showed the significantly better performance of the spacer fabrics owing to the presence of spacer yarns and their contribution towards the thickness reinforcement. Stiffness, strength, and strain capacity of the composite materials were improved using the spacer fabrics. Furthermore, SCM reinforced with 2D fabrics had better mechanical properties than the plain SCM. The flexural bending tests indicated that the composite materials which reinforced with larger mesh have better mechanical performance owing to the easier penetration of the matrix through the fabrics and making reasonable interfaces. There is an increase in the volume fraction of the reinforcement using thicker fabrics with longer spacer yarns which were resulted in higher modulus and strain capacity. The SEM images indicated that matrix cracking and then the breakage of the outer layers of the spacer fabrics are the major causes of the composite failure.