Hydraulic cement is a very popular option for concrete crack repair, but what most consumers don’t know (and eventually find out), is hydraulic cement is only a bandaid and can’t actually repair a concrete crack.
Concrete, or any cement-based material, is comprised of water which is why when it cures, it shrinks. Some concrete shrinks as it dries, some concrete shrinks further down the road. This “shrinkage” is what causes most cracks in foundations, concrete driveways, walkways, etc. Hydraulic cement, for the most part, is concrete. It too will eventually shrink. It can’t be injected into a crack and therefore, can only provide a temporary seal to surface cracks. Further, concrete can’t bond to concrete (or any other material). At best, concrete can lay on top of other concrete and will eventually just “pop” off.
To summarize: Why can’t hydraulic cement repair concrete cracks?
- Hydraulic cement is comprised of water – eventually the cured material will shrink allowing the crack to reform – or allowing for new cracks to form around the hydrualic cement repair.
- Concrete can’t bond to concrete. Hydrualic cement will lay on top of already existing concrete. Over time, the hydralic cement repair will eventually “pop” off.
- Hydraulic cement can’t be injected. It is merely used as a surface bandaid.
So if you can’t repair your concrete crack with hydraulic cement, what can you repair it with? The two obvious choices would be polyurethane foam or epoxy. Epoxy is a very strong material but it isn’t very forgiving. Repairing a crack with epoxy will provide structural repair but nothing is to stop cracks from forming around the repaired area. Further, epoxy can’t be used where water is present. So, if you have a wet, damp, leaking, or gushing crack – you can’t use epoxy. Some epoxies can only be used indoors and the instructions and circumstances in which you can use epoxy are very specific. Polyurethane is more flexible but just as strong. It bonds to the concrete creating a seal that will stop water, insects, and radon. It isn’t porous and offers a permanent solution to concrete crack repair.