There is a popular concrete stem wall repair service that that tries to make themselves out to understand the complexity of the problem. They claim to put rust inhibitors on the existing rebar…. or replace it….. and then patch the concrete back with a super-duper Army Core of Engineers cement approved patch material. And then offer a warranty that covers only a few years.
Why only a few years? Because there are several problems with this approach that limit its effectiveness over time. First, putting a rust inhibitor on rusting rebar will do no good unless the rebar is sand blasted to a white metal condition. That requires chipping out 1” behind the rebar. Why? Because the International Concrete Repair Institute (ICRI) procedure for this requires that the entire bar be in white metal condition before putting on a rust inhibitor.
Reference: https://cdn.ymaws.com/www.icri.org/resource/resmgr/2016_fall_convention/1_Fri_02-F2016.pdf
Here is another protocol from American Concrete Institute (parent organization to ICRI): https://www.concrete.org/portals/0/files/pdf/rap-6.pdf
Even with this procedure, the repairs are not expected to be permanent. How long will they last? No one will give a concrete answer…. It depends on how well the sand blasting is done, if the rust inhibitor coating is done without any pin holes, how aggressive the environment is and many other factors. The point is if the important prep work is neglected, the repair will be lucky to last a few years…. Hmm …..sound familiar?
It really makes no difference how wonderful the concrete patch material is, it will still fail. All cement based products have low tensile strength (pulling apart). When rusting rebar continues to rust with continuing electrochemical micro currents in the concrete it will split any cement based product apart over time. (See my previous blogs on this subject: https://www.foundationaz.com/blog/repairing-a-stem-wall-repair https://www.foundationaz.com/blog/repairing-a-stem-wall-repair)
I was vexed by the problem for many years. I struggled to sand blast completely, coat the entire exposed rebar completely and patch back using an anodic modified cement patch material…. the concrete stem wall repair still did not last long enough. I eventually experimented and developed the patented NeveRust® Stem Wall Repair System. It not only replaces the rebar with composite rebar, but also the hold down straps and temporary shoring jacks all with composites. Learn more about NeveRust® here: https://www.foundationaz.com/blog/composite-stem-wall-repair-system
I am happy to warranty any replacement that we have done against ever rusting again… for life - even if the home is sold! That is a concrete repair you can feel good about.
Check out a recent concrete stem wall repair, before, during & after NeveRust® Stem Wall Repair System was installed:
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