Alchatek Blog

Sealing Leaks in Concrete with Polyurethane

Water is RELENTLESS. Leaks appear in all kinds of structures, from underground parking garages to municipal treatment tanks to elevator shafts. Everything from fine hairline crack leaks to gushers can threaten the long-term integrity of the structure and surrounding property. Fortunately, pressure injection of polyurethane grout into the crack or behind the leaking wall (depending on the application) creates a durable and rugged positive side repair. A relentless solution to a relentless problem.

A wide variety of leak seal solutions are available to address almost any type of concrete leak. (Call the Alchemy-Spetec technical support team at 404-618-0436 for assistance in choosing a product for your specific project.)

Polyurethane Leak Seal Solutions - Crack and Joint Injection

Crack and joint injection products are generally used for smaller non-gushing leaks:

Spetc PUR GT380
Activates as Foam or Gel Depending on Amount of Water Added
Ideal for Manhole Rehabilitation

Spetec PUR GT500
Most Dry-Cycle Resistant Hydrophilic Grout
Ideal for Cracks with Intermittent Leaking

Spetec PUR GT350
MDI Based Grout
For Wet Dynamic Cracks & Joints

Spetec PUR F400
Flexible Hydrophobic Grout
Ideal for Dynamic Cracks & Joints

Spetec AG200
Acrylic Injection Resin
Used in Special Situations (Contact Alchemy-Spetec Support for More Info)

Polyurethane Leak Seal Solutions - Curtain Grouting

Curtain grouting products are generally used for gushing leaks or multiple smaller leaks in proximity:

Spetec PUR H100
Semi-Flexible
Ideal for Structures with Some Movement

Spetec PUR H200
2,050 psi Compressive Strength, Fastest Cure Time­­
Ideal for Soil Stabilization

Spetec PUR Highfoamer
50x Expansion
Cost Effective for Large Voids

Spetec Boom! Seal
Two-Component, High Expansion (35x), Hydro Insensitive
Used in Special Situations (Contact Alchemy-Spetec Support for More Info)

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A contractor in Atlanta was recently called in to seal off a rain-induced ceiling leak in a new construction high-rise penthouse suite. Sealing off the water intrusion from the roof above was not an option, due to the rooftop swimming pool directly above the penthouse. So, they had to get into the ceiling from the interior of the suite and repair the leak from the underside.

Powerful Polymers

The crew on this job injected Spetec PUR F400, a water-reactive, hydrophobic, flexible, single component polyurethane resin. This product is ideal for sealing off active leaks in cracks.

Painless Procedures

Leaking concrete structures can be permanently repaired with concrete crack injection & curtain wall procedures using water-activated polyurethane foam. Pressure injection of these liquid polyurethane resins forces the material into leaking cracks or behind leaking walls depending on the application. After the polyurethane injection is complete, the polyurethane resin rapidly reacts with water to form a watertight seal.

Rapid Results

In this case, the leak was shut down in less than two minutes. This all went down literally right before the new tenant was scheduled to begin moving in. (No pressure there!)

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What Causes Leaks in Concrete?

Imperfect Construction
Concrete construction is by no means a perfect science. New construction often requires Leak Seal treatment follow-up work. If the initial construction isn’t properly sealed at the time of construction, leaks are bound to appear sooner rather than later.

Weather and Wear
Concrete naturally decays over time. Exposure to extremely hot temperatures and extremely cold temperatures can take their toll over time. Even structures located in mild climates will begin to decay purely due to the aging process.

Unstable Soil
Unstable soil can undermine the integrity of concrete structures and cause cracks to appear. Loose soil has four main causes: soil erosion, poor compaction, freeze/thaw cycles, and biological decay. If soil is the main culprit, additional stabilization and slab lifting treatments may be required in order to prevent further cracks from appearing.

What is Curtain Grouting?

Curtain grouting is the process of injecting water-reactive resin behind the leaking wall in a grid pattern (from the negative side). The water on the other side mixes with the grout and cures to a solid mass covering the surface of the wall on the other side (positive side). In addition, you don’t have water pressure dislodging external “patches” over time, as can be the case with other methods.

Curtain grouting is often required when there are gushing leaks, multiple leaks in proximity, cracks cannot be identified, the walls are made of material that does not respond well to crack injection (such as masonry, stone, and CMU), or previous leak seal methods have failed.

The most well-known Alchemy-Spetec product for this application is Spetec PUR H100, a one-component, closed-cell, hydrophobic, water-reactive, solvent, and phthalate-free, low viscosity resin. If there are large voids involved, Spetec PUR HighFoamer (a similar product with a higher expansion rate) may be a more cost-effective option.

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Crack Injection Explained

Crack injection has many advantages over other methods.  For example, if you’re sealing a leak in a water tank, you can inject from the outside of the tank. So the tank can remain in service while you repair it. Having to dry a crack, like you do with epoxy resin, is not needed as this material reacts with water. The material also remains flexible at all times.

Crack injections can be applied in both vertical cracks and in horizontal cracks. With vertical cracks, it is imperative to start at the bottom of the crack and work your way up the crack until it is filled. This forces the material up and through the crack and will simultaneously push the water up and out as well. With horizontal cracks, injection can be started at either the left or right end.

Read more from Charlie Lerman's article Crack Injection Explained.

Curtain Wall Grouting Explained

Curtain wall injection is the process of drilling holes through a structure in a diamond pattern, then injecting the grout into soil on the other side. This procedure creates a curtain wall made of a resin/soil mixture that prevents water from getting back into the structure. It is often required if there are multiple cracks or leaks in a wall. Filling each individual crack may cause you to waste time following the water from crack to crack. Curtain wall grouting allows you to stop multiple leaks at one time and protects the structure on a long term basis.

This procedure was first performed in 1960 on a sewer manhole with a multiple leak problem. As described above, chemical grout was injected through to the outside of the manhole. This created a “positive side seal” (on the side the water was coming from), blocking water from penetrating the joints of the structure.

Read more from Charlie Lerman's article Curtain Wall Grouting Explained.

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Planners at Washington D.C.’s water utility, D.C. Water, decided to take proactive measures against potential flooding of their facility. Located right next to the Potomac, their facility could’ve been at risk in the event of an out-of-the-ordinary natural disaster. Determining that the main risk to the water supply in such a case would be permeation through sub-surface soil, they began installing a metal sheet pile wall deep into the substrate between the riverbank and the facility. However, in some spots they were not able to drive a sheet pile panel into the ground because of underground utility lines or rocky substrate. The planners called in LJS Waterproofing to create sub-surface grout walls in those spots to fill in the gaps.

Powerful Polymer

The LJS crew “constructed” these sections of the underground wall by injecting AP Fill 700. This is a single component, water-activated, hydrophobic, low viscosity, closed-cell polyurethane injection resin. This grout was used because it permeates the soil, fills small voids in the soil, and cuts off water flow.

Painless Procedure

LJS professionals used a Geoprobe to drive injection pipes into the ground (up to 33 feet in some locations). They then injected one gallon per foot using upward staging. The next injection point was 18 inches away from the first one. This process was repeated until a grout wall formed, filling the gap between the two adjacent underground sheet piles. For a large-scale job like this, LJS used the PolyShark single component grout pump.

Rapid Results

With solid, impermeable grout walls filling in the gaps, a sub-surface barrier between the riverbank and the drinking water facility was now in place. The planners at D.C. Water were very satisfied with this solution. LJS Waterproofing came through exactly in the way they had promised.

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The administrators of a church in Kingston, New York discovered water leaking through a wall into a hallway. The leak was located right next to the elevator. As water seeped into the elevator pit, it became flooded. Elevator pits often contain oil from hydraulic leaks in the equipment. Disposing of that oily water over and over can cost a property owner tens of thousands of dollars over time. The administrators reached out to LJS Waterproofing for assistance before the problem drove their budget through the roof.

Powerful Polymer

The LJS crew injected Spetec PUR F400 polyurethane grout to stop the water infiltration. This material reacts with the water inside the concrete cracks, curing to form an impenetrable seal. Chemical grouts are the most reliable way to shut down leaks in concrete.

Painless Procedure

1. Concrete crack injection with polyurethane resin is a five-step process:
2. Drill the injection holes.
3. Flush debris out of the holes with water.
4. Install the injection port.
5. Flush the crack with water.
6. Inject the resin.

For a complete overview of the crack injection process LJS professionals used on this job, see the Alchemy-Spetec blog post series 5 Steps of Concrete Crack Injection.

Rapid Result

The crew finished the repairs in a timely manner, saving the church a great deal of money in the process. The hallway is now completely dry and the elevator pit is no longer flooding. An ounce of prevention, in this case, was definitely worth a pound of cure!

Want more information on Alchemy-Spetec leak seal products?

Aging infrastructure is a common problem in municipalities across North America. Wastewater treatment tanks with leaking cracks are a particularly serious problem because the result is often environmental contamination. Administrators at a wastewater treatment plant in New York City contracted LJS Waterproofing to repair 39 leaking concrete tanks. An experienced LJS crew arrived on the scene shortly thereafter, ready to take on this critical threat to the environment.

Powerful Polymer

The LJS crew injected Spetec PUR F400 to seal the leaking cracks. This material is a solvent and phthalate-free, water-reactive, hydrophobic, closed-cell, low viscosity, shrink-free, flexible, one-component polyurethane injection resin designed to shut off water leaks.

Painless Procedure

Concrete crack injection with polyurethane resin is a five-step process:

1. Drill the injection hole.
2. Flush debris out of the hole with water.
3. Install the injection port.
4. Flush the crack with water.
5. Inject the resin.

For a complete overview of the crack injection process LJS professionals used on this job, see the Alchemy-Spetec blog post series 5 Steps of Concrete Crack Injection.

Rapid Result

LJS Waterproofing sealed every leaking crack in all 39 concrete tanks, preventing any future wastewater from leaking into the surrounding environment. The administrators at the New York City wastewater treatment plant were extremely happy with the results.

Want more information on Alchemy-Spetec leak seal products?

This article is an excerpt from Episode 13 of Alchemy-Spetec's podcast The Injection Connection, featuring Erin Rothman - Founder and CEO of StormSensor. (If you'd rather view or listen, an audio/visual version of this excerpt is posted at the bottom of the article.)

Charlie Lerman: Do you ever get involved with EPA Consent Decrees where they've said to a municipality, "Your system's all hosed up. You need to get this fixed and you're going to do it in this time frame." Did they ever call you in for that type of monitoring or anything like that?

Erin Rothman: The consent decree programs we've been a part of have been on the combined sewer side. And a lot of that is looking at obviously when overflow is happening, how significant the overflow is. We can quantify it given in tidal locations, so being able to separate different tidal sources or flow sources. But then, really, in doing that, helping them really understanding the total volume that needs to be addressed instead of the modeled volume and incorporating that into long-term control plans.

Charlie: Gotcha. Because a lot of municipalities, especially when they're slapped with a consent decree, just think, "We just need to increase the system capacity. We need to make it bigger. We need a bigger plan." Or something like that.

Erin: Yes, increase the budget to pay the fines.

Charlie: Right. And mitigation oftentimes is a great solution that helps or even gets them to where they need to be.

Erin: Exactly. And there are all different ways you can do it. It does not just mean increasing the size of the pipe and putting them over there.

Charlie: No. That's obviously where chemical grouting comes in. That's a small portion of how to control some things. And also with chemical grouting, you find saving opportunities just right there at the manhole. A lot of these people think, “We don't have a budget to start this” or “We don't even know where to start”. But there are some really simple things. When you look at a 10 gallon a minute leak in a manhole - that is roughly, depending what part of the country you're in, between about 12 to $25 000 a year in treatment costs. 

Erin: That's one leak.

Charlie: Right, one leak. And something like that is usually super easy to repair. We're talking a couple of thousand dollars, one day, one crew out there and they can immediately repair it. You see, that $3000 you paid to fix that manhole saves $25000 that year. It's very simple stuff and I really feel that we need some champions out there to get people to understand this. Maybe some type of push with our legislators. This is kind of a passion that I’ve found and it goes great with trying to be more environmentally friendly and saving money at the same time. Who's against this kind of thing? And I don't understand why we're not doing more of it.

Erin: Exactly and providing jobs for the people to do the maintenance and creating those repairs.

This article is an excerpt from Episode 13 of Alchemy-Spetec's podcast The Injection Connection, featuring Erin Rothman - Founder and CEO of StormSensor. (If you'd rather view or listen, an audio/visual version of this excerpt is posted at the bottom of the article.)

Charlie Lerman: How did you get into this and how did you end up starting Storm Sensor? 

Erin Rothman: I think everyone's dream is to work in a sewer, so, of course, we start there! But I was a Vice President at a consulting company in Seattle, circa 2010-2011, and we brought in a stormwater group. For the first time in our company's history, we were losing money and we couldn't figure out why. When I talked to my stormwater team, they said that every time it rained at the office, they had to go out and sample their sites. Just because it was raining here doesn't mean it was raining there. So, they're going out like four times before they can collect a sample. And I said, "That's the silliest thing I’ve ever heard." Why don't we just have a rain gauge that texts us when it rains? And they said, why don't you go invent that? And I said, I will, I'm going to call it StormSensor. That's how it started as a little sparkle in my eye, but I had no hardware or software experience at the time. And I didn't know if I could even begin to put together a company like that. But as I started talking to more people in the stormwater industry and learned that there was a lot of frustration - and so much of it related to not knowing what was going on within these systems, I realized that maybe I could solve this problem with a team of brilliant people who could actually build the things that were in my head. That's how it started.

Charlie: That’s spectacular.

Erin: Yeah, I started with construction and industrial compliance because that was my background. And I started talking to cities and so many of them said they just needed to know how much water was moving through their storm system. That it wasn't metered and they didn't know. That just opened up a world of opportunity to me.

Charlie: Wow! That’s excellent. When you deal with below-grade infrastructure, there are a lot of needs but they're not really well defined. Nobody even focuses on them because it's out of sight out of mind. And I often say even for grouting, Alchemy-Spetec's biggest competitor is not another grout company - it's ignorance. People just don't understand that this kind of technology, these types of repairs (or your monitoring system) are even out there. And I think that's because municipalities are on tight budgets obviously. We want them that way, we don't want to just throw money at them. We want them to use the funds correctly. But you get a lot of people who start off at low-level positions in municipalities and then there's turnover, they move up, they go on to other things. And a lot of information is lost there. So, it's not necessarily that the government's just bad. It's kind of the nature of it, we all want to grow in our careers but these things get left behind.

Erin: Absolutely. And then the people paying for it, the citizens and taxpayers, want to see the benefit of what they're spending their money on. If you can't see it, then why would you pay for something that you can't see, that you can't understand? If you wait to fix it is once it stops working, it's too late because you're dealing with flooding and backups and paying too much for treatment and everything else.

Charlie: Oddly enough, it’s going back to that study I mentioned earlier in this interview, the 188 million dollars for I&I repairs - paying that is actually the easy part of it. What it comes down to is that inflow also causes damage to infrastructure. You see sinkholes and damage to property, potentially harmful or life-threatening conditions. And then, when these systems overflow, you're putting septic out there in the public, damaging our waterways and our health.

Erin: Yes, and sometimes even our homes and our businesses and the people who live and/or work there. It's becoming a lot more common.

View the video version of this excerpt...

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This article is an excerpt from Episode 13 of Alchemy-Spetec's podcast The Injection Connection, featuring Erin Rothman - Founder and CEO of StormSensor. (If you'd rather view or listen, an audio/visual version of this excerpt is posted at the bottom of the article.)

Charlie Lerman: Have you ever found or identified anything that’s just an anomaly, something that's completely unexpected that you surprised the city with, or anything like that?

Erin Rothman: Once or twice, yes. One example was in Memphis. We were working as part of a larger group to do a model validation study for the storm system because Memphis was dealing with a lot of flooding. And most model validation studies have sensors that are deployed in a limited number of locations and for a very short period of time - one to three months usually. We were deployed for about six months before we got a call claiming that all of our sensors were broken because we were reading four feet of depth, four feet of water in all of the pipes. And that it was flowing backward, and all that was impossible. This is why whoever was running the project didn't like new technology.

But we're thinking like, for every sensor to show this, there's got to be something. I mean, we've never seen it with even one sensor, but if the whole thing's acting up... So, we called the city and they had no idea what was going on. We asked them to go check it out and they came back and said, "Oh, my gosh, there is four feet of water in these pipes and it's flowing backward!" What could possibly be going on? So, they talked to the guys at the plant on the Mississippi River and they said, "Oh, yeah, every time the river hits a certain stage, we open up the gates and then use the storm system for storage." But you're telling me that it goes more than a mile into the system.

So, what we had is a situation where no one really understood that the river was filling the storm system and taking up at least half the capacity on a pretty regular basis. So, when you combine heavy rain and high-water levels, all of which are going into a storm system that is designed to hold only rainwater, you have some pretty significant flooding impacts. Now, what they do is before a storm comes, they close the gates, empty out the storm system, and clear that out.