Cracks in cement walkways, driveways and patios are common and should be repaired. Cracks will allow water to seep in and over time the damaged surface will degrade even more and may become a safety hazard. Repairing cracks can usually be done in a few hours and is relatively inexpensive.
Soil shifting or sinking is a common cause of cement cracking. There is a good chance that the patch will break in a few years from the same shifting that caused the original crack in the cement so you will have to repeat this process. Not necessarily what you want to hear, but often realistic, so easy and inexpensive is a good choice.
The cement patch will be hard to disguise since the mortar will have a different color from the main surface. This is usually not an issue, and aging will lessen the color difference.
You will need the following tools:
wire brush, stiff paint brush, hammer, chisel, broom and/or shop vacuum, garden hand spade, cement (see first step), water hose, spray bottle, bucket to mix cement ( mop bucket size)
Your first step is choosing the type of material you will use to fill the crack. Go to your favorite building supply store to get the patching cement. Do not use a concrete mix for small cracks because it contains gravel which makes it harder to smooth. Depending on the size and depth of the cracks, and perhaps even your strength, you can get quick setting cement in as small as 10 lb buckets and up to 60 to 80 lb bags of mortar mix type S. For all of these you just have to add water. The difference between quick setting cement and mortar mix is mainly price and set up time – results are the same.
Your second step is preparing the area for patching. Wear gloves to protect your hands and old clothes – mortar can irritate your skin and will stain. Remove cracked, loose cement and debris with a wire brush or broom. For loose but stuck pieces that you can’t get with the wire brush gently use a hammer and chisel to loosen and remove. For repairs wider than 1/2 inch, gently use a hammer and chisel to widen the bottom of the crack to the same width as the top. This will give the patching material more surface to stick to and hold it in place better. Use a broom or shop vacuum to clear dust and small material.
Your third step is to prepare the patching material. The quantity to mix depends obviously on the size of the patch. For example, start with 6 cups of dry cement to repair a 1 inch wide crack across a 2 foot wide walkway. Scoop the cement into the bucket, add water a little at a time, use the hand spade to stir the mixture blending the mix until thoroughly wet. Continue adding cement mix or water until you have slightly more than you think you will need. Let the mix sit for a few minutes.
Your fourth step is to use a water hose or spray bottle to wet the cracked cement surface but do not leave any standing water. Wetting the area will allow the cement to adhere to the surface but excess water will dilute the mixture too much.
Your fifth step is to scoop or pour the cement mix into the crack using the hand spade, pushing down on the mortar to force it to fill up the space. Use the hand spade to roughly level and smooth the mixture with the surface. Work slowly and carefully to spread and smooth the mixture. If you push too hard the mortar will come out – just smooth it back in. An alternate method is to use a 1 to 2 inch wide paint brush to spread and smooth. Get a small can of water and dip the brush lightly into it, shake off the excess water and then spread/smooth the mix. The water allows the mix to flow – but don’t overdo the water. Dip and shake the brush tip often as it will get sand on it. Let the material dry about an hour or more and then repeat smoothing the surface if needed. The brush works particularly well on rough surfaces for spreading and smoothing the cement mix.
Your sixth step is to clean the bucket and other tools with water as soon as you are finished – once the cement hardens it is very difficult to remove.
Let the cement patch dry for 24 hours before stepping on it.
