Active water leaks in your concrete can be more than just a nuisance. Everybody has them. That area that stays wet all the time, especially after it rains. As long as it’s not inconvenient or posing a safety hazard, most people just overlook it. “It’s just always wet, that’s all.”
But, the truth is, those concrete structures are reinforced with rebar. The rebar adds a great deal of strength to the structure. However, the rebar is also very susceptible to damage from corrosion. And, all that water brings the oxygen with it that drives the process forming rust and eventually concrete failure.
Stopping the active leak is critical to stopping the flow of water. This is the first step to stopping the degrading of your concrete’s ability to perform as it was intended to.
Choosing the right approach to your leak is key to applying a permanent repair. Let’s take a look at some methods you could employ to stop active leaks in your own or your client’s structures.
Urethane Grout Injection
Urethane grouts are water activated. When they come into contact with water, they expand at a predictable rate creating a foam. The idea is to inject them into a confined space filled with water. The expansion would allow for the urethane to create a foam many times it’s original volume. But, because the space is confining it, it becomes more and more dense until it completely cuts off the flow of water.
Flexible Membrane Striping
A flexible membrane is a material that is very flexible, has high bonding properties and can work in submerged conditions. These are meant to be applied in a positive-side pressure situation. Meaning, they are on the inside of a tank or other structure that is usually filled with water. These materials are often flexible urethanes or polysulfides.
Rout and Seal Cracks
This is another positive side only application. Using this method, you rout out the cracks so that a high bonding material can be used to fill the area where water would enter the crack. Sealants are commonly used for this. However, flexible cement mortars are also very effective.
Coat Interior of Structure
Of course, creating a membrane covering the entire interior surface of the tank or structure would address any current leaks as well as any cracks that may have been inactive prior to the repair of those that were obvious. Coating are also an option for isolated problem areas like a particular pour that has cracking or voids that most of the structure does not.
Install Curtain Wall
A curtain wall is a urethane grout barrier on the outside of the structure. The urethane is meant to permeate the soil forming a barrier to water moving into the tank and also to keep water from exiting the tank. This is typically used when excavation of the ground around the tank is not possible or would be too expensive.
Apply Crystalline Surface Treatment
Application of crystalline material to the surface is effective if the leaks are very minor. If there are areas that are “damp” but don’t appear to be leaking, this could be a reasonable option. Just make sure you evaluate this during the colder months when cracks become more evident due to shrinking concrete.
Things to consider when selecting the method you’ll use
What’s the expected life of the repair?
You wouldn’t want to repair a tank to last for years if you plan to replace it during the upcoming capital project. You may also be willing to go for a fix that can be applied when it begins to loose its effectiveness to keep the cost down.
What level of expertise is required to perform the repair using that method?
You have to be honest about the ability of the labor you have to do this job with. Do they possess the skill level required for the method you’re leaning towards? You may need to engage a specialty sub-contractor.
How availability is the equipment needed to perform the work?
Do you own the equipment to perform the tasked related to this method? You may be able to rent equipment. Just make sure you have people that can operate it.
Can this method be completed within the time allowed by the schedule that has been set?
You or the owner may have an expectation of the time this will take. If you haven’t done this before, make sure you seek advice from someone who’s familiar with all aspects of the repair.
What methods would be possible given the budget provided?
You may have to offer a less effective or shorter term option if the owner doesn’t have the budget for the Cadillac. It’s not the end of the world if the client doesn’t go with the best solution as long as you can give them your best effort at the solution, they are willing to pay for.
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