Repairing Concrete steps is fairly easy, while casting new concrete steps requires quite a lot of complicated formwork and is tricky to get right. If you need steps in your garden, it is better and easier to build them from pre-cast slabs and blocks, or even bricks. If, however, you have existing concrete steps on your property, it makes good sense to keep them in good order.
Even the best made concrete steps will suffer the effects of weather over time. Spalling is common, as are chipped and broken edges, especially on the nosings (front edge of each step). This can make them not only look terrible, but also make them less safe than they could be. Being able to repair your spalled concrete steps is therefore an important DIY skill.
Repair Concrete Steps
Small chips and cracks less than 1cm deep are tricky to repair as there is little for the new concrete to adhere to. As the chip will undoubtedly get worse, it is better to chip away a little more of the concrete yourself (wearing safety goggles, of course), in readiness for the repair.
You now need to find a board that matches the height of the riser (front face of the step) and at least 20-30cm wider than the area to be repaired. A cheap or old pine shelf is often great for this. Prop the board flat against the riser and hold it in securely place with a couple of blocks or bricks.
Mix up a small batch of general purpose concrete and add some PVA bonding agent to it. The bonding agent will help the concrete adhere to the step and is widely available from DIY stores. Now dilute some of the bonding agent with water (3pts water, 1pt PVA) and brush this onto the chipped area, making sure you work it into all the cracks and crevices. Let this dry for a short time until it is tacky.
Creating an Edge
Now fill the gap with the concrete mix. The board against the riser will form the front of the step, so concentrate on filling the hole completely and getting a nice smooth finish on the top. Let the concrete dry very slightly and then run a float at an angle along the board where it meets the concrete. This will create a safer beveled edge rather than a sharp edge.