Scrape the damaged area of the step with a 2-inch putty knife. Gently scrape the putty knife over the area to remove loose pieces of concrete. The repair will be more successful if the cement has solid concrete to which it can bond.
Sweep the damaged area with a hand broom to remove pieces of concrete and other debris. A clean surface provides a good foundation for the repair.
Mix the hydraulic cement in a bucket with water according to the directions on the package. Use the putty knife to mix the cement to a consistency similar to thick oatmeal.
Dip the 6-inch drywall knife into the bucket and scoop up some of the cement on the end of one side of the knife.
Smooth the cement into the damaged area, making it level with the rest of the surface. Use the very edge of the knife to scrape up excess cement and throw it back in the bucket. Completely fill in the damaged area and make it as smooth as possible. Let the cement dry thoroughly for a couple of hours before walking on it.