Bond Behavior of Carbon Fabric-Reinforced Matrix Composites: Geopolymeric Matrix versus Cementitious Mortar

This study aims to examine the potential use of a geopolymeric matrix as a sustainable alternative to commercial mortars in carbon fabric-reinforced matrix composites. Single-lap shear tests were conducted to examine the bond behavior at the fabric-matrix interface. Test parameters included the type of matrix (geopolymeric and cementitious matrices) and the bonded length (50 to 300 mm). The geopolymeric matrix was a blend of fly ash/ground granulated blast furnace slag activated by an alkaline solution of sodium silicate and sodium hydroxide. The bond behavior of the geopolymeric-matrix specimens was characterized and compared to that of similar specimens with a cementitious matrix. The specimens failed due to fabric slippage/debonding at the fabric-matrix interface or fabric rupture. The effective bond lengths of the geopolymeric- and cementitious-matrix specimens were 150 and 170 mm, respectively. The geopolymeric-matrix specimens exhibited higher fabric strains, higher ultimate loads, and a steeper strain profile along the bonded length than those of their cementitious-matrix counterparts. New bond-slip models that characterize the bond behavior at the fabric-matrix interface for geopolymeric- and cementitious-matrix specimens were developed. Both models exhibited equal maximum shear stress of 1.2 MPa. The geopolymeric-matrix model had, however, higher fracture energy and higher slip at maximum shear stress than those of the cementitious matrix model.