If a big chunk of concrete broke off a step, you can repair it without having to spend money on taking out the old concrete and rebuilding the entire steps. If, however, the steps are generally in pretty bad shape — with crumbling concrete on the surface and deep cracks in other parts — then the steps should be replaced.
Repairing a large broken edge is similar to repairing a small piece of concrete, but you need to put a rod into the sound portion and the new edge. You need a wire brush, a latex bonding product, concrete patching material, scrap boards, re-rod, a drill with a masonry bit, and some concrete blocks or adhesive tape to hold the boards in place while the patch cures. Here’s what to do:
With your masonry bit, drill a hole into the center of the break into which you can insert a steel dowel, called re-rod.
Get all loose pebbles and dirt off the step or the bonding agent won’t adhere as tightly as it should. The rod will help reinforce the patch.
Clean the broken edge of the step and blow out the hole, coat the rod and the hole with bonding material, and pound it in, leaving half its length sticking out.
A turkey baster works well for blowing debris from the hole.
Apply the latex bonding material to the broken edges of the step.
If you use a liquid, you can brush it on and make sure it reaches into all the crevices.
Mix the patching compound with water and the bonding agent that you used in Step 2.
Read and follow the manufacturer’s directions. The mixture will be thick and look like wet concrete. Be careful not to get it too wet because then, even though it’s easier to work with, it will not make a strong bond or hold up for long.
Place the scrap lumber up against the step to make a form.
Tape it on or use some cement blocks to hold it in place, or screw or nail the boards together at the corner.
Use a trowel to apply the thick mixture to the top and sides of the step, tamping it into place and smoothing out the top.
Experiment with matching the rest of the step. Stipple it with the tip of a dry brush or wash a little cement off the top to make it look old.
Cover the patch with plastic if you expect it to rain within the next 24 hours.
It doesn’t matter if the patch gets a little wet, but you don’t want rain drumming into it because too much moisture will limit its strength.
After 24 hours, take off the plastic.
Leave the boards in place for a week while the concrete cures.