You can alter small exterior concrete steps extending from a patio or directly from a home. For instance, if concrete stairs are not the correct size, are too small or are different sizes, you can pour new concrete over them instead of redoing the entire structure. The only problem to overcome is that newly-poured concrete does not dry and bond to existing concrete. Fortunately, there is a solution.
Use a tape measure to measure the size of the area in which you are adding more cement.
Put on safety glasses and then measure, mark and cut 2-by-4-inch lumber with a circular saw to create forms for the new concrete pour.
Drill pilot holes into the concrete using a drill with a masonry bit. Fasten the forms to the old concrete with concrete screws using a screw gun.
Mix the concrete in a wheelbarrow by combining 3 parts sand with 1 part mortar and wetting the dry ingredients with water. Mix with a hoe.
Pour bonding agent onto the set cement, then pour the newly mixed mortar. This will "bind" the two concrete pours together. Smooth the new cement with a trowel and let dry for at least 24 hours.
Unfasten the concrete screws securing the forms in place with a screwdriver and then knock away from the new cement with a hammer.