Coating Effects on Ductility of Welded Wire Reinforcement

Welded wire reinforcement (WWR) offers improvements in constructability over conventional rebar but suffers from low ductility because of cold working. WWR is often epoxy coated or galvanized to improve its resistance to corrosion. The associated heating from the coating processes may improve ductility, adding additional value of coating to WWR and improving member performance. The authors hypothesize that epoxy-coated and hot-dip-galvanized WWR have higher strength, stiffness, and ductility than uncoated WWR. To test this hypothesis, experiments were performed to measure the yield strength, ultimate strength, modulus of elasticity, and elongation in uncoated, epoxy coated, and galvanized WWR in D11, D20, and D31 wires. The yield strength and ultimate strength of the WWR were not significantly affected by either coating process; however, the galvanizing process resulted in significant increase in uniform and total elongations. The authors present a case study to compare section ductility in reinforced concrete slabs with uncoated and galvanized WWR elongations at the minimum and maximum allowable reinforcement ratios. Depending on section length and reinforcement ratio, the increase in ductility of galvanized WWR translates to a 10%–50% increase in section ductility.