Concrete Foundation Repair & Waterproofing
You have noticed horizontal cracks in your outside foundation stem wall. This could be a serious problem. Usually these horizontal cracks are a result of the rebar oxidizing.
When rebar rusts it grows in volume putting pressure on concrete, at first cracking it and given enough time causing spalling and eventually splitting it as the rebar dissipates in entirety. This is caused by chloride ion exchange in the moisture laden pores of the concrete that facilitates the oxidization of the rebar.
Once started is very difficult to stop with traditional means. Sealing the crack with epoxy will not stop the rebar from continuing to oxidize and expand.
The proper fix is to expose the rebar, sand blast to white metal on all sides, coat with an ion blocking epoxy, and patch the concrete with anodic inhibiters that stop the electrical current in the concrete. The following steps are illustrated to better understand this process.
Cracks may start out small, but continue to grow like the picture above. These cracks are a result of oxidizing (rusting) rebar. This occurs because the pores of the concrete contain minute amounts of water that actually conduct electricity forming a tiny current between the rebar and the out side of the concrete facilitating a flow of chloride ions that cause the rebar to rust. Eventually the rebar grows large enough to break the concrete out completely on its own, causing total failure.
If you attempt any repairs to the concrete with out first dealing with the chloride ion flow, the rebar will continue to oxidize and break out the concrete. The steps to repair this phenomenom are as follows:
1. Chip out the concrete to reach the rebar.
2. Next you sandblast the rebar and then coat it with an ion blocking epoxy.
3. Then you the concrete is patched back with cement patch material that has an anodic inhibiting agent in it.
4. The concrete is then finished to look like new!!!