If the concrete in question is structurally sound and it is only the top layer that is pitted or has chipped away, it is possible to resurface the old concrete and make it look like new, at a fraction of the cost of having new concrete poured.
Steps:
- Clean off any debris from the concrete. This includes, loose pieces that may have not flaked off yet, but will. Use a hammer and tap the top of the concrete, you will be able to tell the difference between solid concrete and areas where there is air below the surface layer. In areas where you detect air, use the hammer and crush the loose surface layer. The use of a high pressure washer also works well to loosen any flakey material Any and all oils, grime, and dirt mush also be removed. The new surface layer of concrete will not adhere to any grime or oil.
- Build a wood form around the current concrete in order to have something to pour the concrete into and allow it to set (it is always wise to build the forms "level". If your forms are level you have a guideline for the finished height of the concrete that you are pouring).
- As with any concrete project it is best to pour concrete in somewhat cooler temperatures, ideally 50 to 60 degrees F. If possible avoid working on very sunny and/or windy days.
- Moisten the old concrete.
- Apply a coating of concrete bonding paste to the old concrete.
- Pour the new concrete mix into the form and trowel level.
Concrete resurfacing material is available from any home improvement center (read the label of the product and make sure you get the right product for the thickness you are planning to pour) or you can mix the ingredients together yourself.
Note: General purpose premixed concrete will not work for resurfacing!
For resurfacing layers that are more than 1 inch thick use:
- 6 - parts pea gravel
- 4 - parts sand (use sand that is sold as concrete sand).
- 3 - parts Portland Cement.
- Water - the consistency should be such that it will stay in a mound and not freely flow.
For resurfacing layers that are less than 1 inch thick use:
- 3 - parts sand (use sand that is sold as concrete sand).
- 1 - part Portland Cement.
- Water - the consistency should be such that it will stay in a mound and not freely flow.
In both cases make sure that the cement is thoroughly mixed. Failure to have a homogeneous material will result in pitting, cracking and flaking of the resurfaced material.
Additional information on decorative concrete
Additional information on repairing cracks in concrete