Caulking Concrete Cracks (DIY) | Family Handyman
Fill the crack with urethane caulk, similar to what you would use for driveway caulk. It works perfectly as a concrete expansion joint sealant. Snip the opening of the tube at a 30-degree angle, making the opening the same size as your gap. Use a smooth, even motion, filling the crack flush with the surface, beveling it if it's against the house.