What is the Largest Crack that can be Repaired with Epoxy Injection
A reader writes:“What is the largest concrete crack that can be injected with an Epoxy Injection repair?”
For concrete outdoors and/or is going to see extreme temperatures, you
would typically want to limit your injection to about 1/4 inch. If the
crack is larger than that you may experience some thermal coefficient issues, if
injected using normal epoxy concrete injection techniques.
Thermal coefficient is the rate that materials expand and contract due to
temperature changes. Neat epoxy resin expands at a rate greater than
concrete. In small cracks this is not important, but as the mass of epoxy
gets greater, the potential for differential movement gets greater.When I have been forced to epoxy inject these cracks larger than 1/4 inch
I like to use Epoxy.com Product #301 – www.epoxy.com/301.htm..
Epoxy.com Product #301 is is a low mod (more “flexible”) injection
material and is less likely to create a thermal co-efficient problem than a
high modulus material.
If the crack is still bigger, I try to pack as much Epoxy.com Product
#703 – www.epoxy.com/703.htm -
Low-Mod Epoxy Gel Adhesive as I can into the crack. First I place
copper tubing as far back into the crack as I can. Then I fill out to
the surface with the Epoxy.com Product #703. If the crack is large
enough you can also mix up to 1 part silica sand with 1 part of mixed
Epoxy.com Product #703. Mixing in the silica sand saves material
costs, and makes the Epoxy.com Product #703 easier to trowel. Most
importantly the thermal coefficient of the Epoxy.com Product #703 and silica
sand is much closer to that of concrete than the Epoxy.com Product # 703 alone.
After the Epoxy.com Product #703 has hardened, you can pump the Epoxy.com
Product #301 into the copper tubes that were inserted earlier. This
results in a very effect, well designed and engineer solution for larger
cracks. When in doubt how to proceed with larger cracks, please contact me
at Epoxy.com Technical Support – 352-533-2167 or by email at