August 15, 2012
Which is better, epoxy injection or urethane injection? That is a little like asking which is better a 1/2 inch wrench or a 3/4 inch wrench. The answer is whichever one is the Right Product for the Right Job. This blog will explain this in more detail.
Epoxy injection should always be used in cracks where two sections were never meant to be separated. For example a crack that took place in a piece of concrete that was intended to be monolithic (single pour), or where two sections of wood need to be bonded together. These repairs should always be by epoxy injection.
Urethane injection should always be used where the two separate members (pieces of structure) were never intended to be attached firmly but need to be waterproofed. Consider for example, a sewer pipe and a basement wall (between a pipe and the concrete where it passes through the concrete).
Engineering determinations are required in places like a cold joint or the space between two sections of precast concrete. If the structure is better off by the two members being bonded together, then epoxy injection should always be used. If the structure is better off by the two members being able to have slight differential movement from each other and/or should never be bonded together, then urethane injection should always be used.
Please Like us on Facebook: www.facebook.com/epoxy.com
April 22, 2010
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