Aboweld is a two-part epoxy for concrete repair. It’s impermeable, can be applied under water, and bonds to old concrete — which means it can patch anything from swimming-pool walls to concrete stoops. The maker says it won’t sag when wet and can be ground with an angle grinder, then sanded to a finish when dry. Standard and “cold weather” (for use below 50°F) versions are available. A two-quart kit costs about $60.
Abatron, 800/445-1854, abatron.com.