A research on effect of sewage sludge ash on the bonding properties of composite materials

Adhesive bonding has considerable advantages over mechanical fasteners. Adhesively bonded joints have more fatigue resistance because of absence of stress concentrations that occurs at fasteners. Therefore, the need to improve adhesives used for bonding has acquired utmost importance. The present study aims to strengthen adhesive joints. Single lap and double lap configurations were chosen to perform this study. In order to improve the mechanical properties of adhesively bonded joints, micro-particles (45μm and below) of sewage sludge ash (SSA) were mixed with epoxy resin. The weight ratios of SSA added into epoxy were (0%, 5%, 10%, 15%, 20%, 25%) respectively. Glass fiber/epoxy composite laminates with 10 layers were chosen as adherends and the adhesive was produced from different amounts of microparticles added into the epoxy. The adhesively bonded joints with same thicknesses of adherends under tensile and bending loads were investigated experimentally to assess the effect of SSA particles on the mechanical properties of the epoxy. Depending on the tensile test results, the addition of SSA increased shear stress at specified weight ratios of ash. It was found that addition more than 20% of ash particles into the adhesive showed a negative effect on shear stress. According to the three point bending test results, flexural stress affected by addition of SSA particles.