Parallel wires steel-reinforced polymer and mortar for structural strengthening: Introducing and bond properties

This study aims to introduce a cost-effective composite for strengthening/retrofitting concrete elements in bond-critical applications. It comprises a polymeric or cementitious matrix reinforced with parallel high-tensile strength steel wires. 14 concrete prisms were first strengthened with such composites as carbon fiber-reinforced polymer sheets (CFRP), parallel wires steel-reinforced polymer (PW-SRP), and parallel wires steel-reinforced mortar (PW-SRM), and then tested under a direct single lap-shear setup. The study also assesses the efficacy of two surface preparation methods, externally-bonded reinforcement (EBR) and externally-bonded reinforcement on grooves (EBROG), on the bond features of the composites above. In the EBR group, the bond capacity of PW-SRP is 46 % and 85 % higher than that of CFRP and PW-SRM, respectively, while EBROG-CFRP held the first rank in the EBROG group, recording a capacity of 8 % and 54 % higher than the PW-SRP and the PW-SRM. Such results demonstrate the importance and priority of PW-SRP and PW-SRM composites from both resistive and economical considerations. Despite the PW-SRM's low capacity, its cheaper matrix justifies its use. Although the CFRP- and PW-SRM-strengthened samples debonded, the PW-SRP hit the peak failure strain and reached the wire rupture in both surface preparation methods. Moreover, the EBROG kept its superiority over the EBR in the bond capacities of PW-SRP and PW-SRM samples, reaching a capacity of up to 69 % higher than the EBR ones.