The condition of your slab foundation is very important because it supports the whole of your building. If you ever notice any cracks or damage to your concrete slab foundation, it is important to repair the damage right away. There are a number of different ways to repair a slab foundation.
Step 1 - Look for Cracks
Concrete is a very strong man-made material; however, there are plenty of weaknesses. If the temperature becomes very cold or the soil shifts, then cracks can develop. Over time, these cracks grow in size, so it is important that you spot them as soon as possible so they can be repaired.
Small cracks due to temperature changes and the house settling are normal and shouldn't be anything to worry about. It's only when cracks become large that they are a reason for concern.
Cracks can also be caused by moisture, which enters the foundation in a number of different ways. If you are experiencing these problems, then you need to fix the leak before you start to worry about the crack itself.
Step 2 - Consider Using Mortar
One method of fixing and repairing cracks in foundations is to use mortar. Whenever your concrete slab foundation cracks, there will still be small pieces of concrete in the crack. Use a wire brush to clean all of these pieces from inside the crack. If you don't clean the crack properly, then the repair will not work properly.
Mix the mortar with sand and water. It's best to use a ratio of two parts sand to one part mortar. The mortar needs to be mixed thoroughly to ensure it can be applied to the foundation.
Before you apply the mortar, wet the crack with some water. Doing so will prevent the mortar from drying too quickly and failing to stick properly. The water will create a much stronger bond.
Use a small trowel to press the mortar inside the crack, then use the back of the trowel to scrape and level the mortar. Repeat this step as many times as is needed. Don't allow the patch to dry quickly; it should stay wet for two days before drying completely.
Step 3 - Consider Epoxy Resin
If you are having trouble patching the crack, or if the hole is allowing water to enter, then you can use epoxy resin. Epoxy is a strong, waterproof chemical which seals the foundation. Epoxy can be injected deep into the cracks, which will impregnate all of the surrounding area to ensure the problem is fixed.
Step 4 - Consider Hydraulic Cement
Hydraulic cement can be used in exactly the same way as regular mortar. Working with hydraulic cement should be easier because it has a texture similar to putty. It can be pushed and compacted into the hole so the repair is completed as easily as possible.
Step 5 - Consider Professional Help
If the problem is something that you don't feel confident fixing alone, then you should consider hiring a professional. A professional contractor may be expensive; however, he will know exactly how to repair the crack.
If you believe that the problem has been caused by soil shifting under the house, hire a professional. The soil will need to be stabilized before any foundation repair can be of use.