Snap ties are metal tabs installed in the concrete forms when concrete is poured to hold the forms together. Snapped off to release the forms most of the metal tab is left inside the concrete. Over time they can rust and allow water to enter the foundation. Using hydraulic cement, tar or polyurethane to repair is not recommended because they may fail eventually. The best solution is to use an ultra-low viscosity epoxy to encapsulate the rusting snap tie and provide a permanent solution. The typical repair product solution is #4 ULV Epoxy with an autoinjector.