Polyurethane chemical grout injection can be a bit of a Pandora’s box at times. So, what can be done to help combat some of these uncertainties? Well, how about the easiest and most cost-effective solution first. Oakum! Not only is it amazing what you can accomplish with it, but it is vital to have on every job. YES, I SAID EVERY JOB.

There are only two things that have to happen for successful water mitigation. One, get the grout to the right location. Two, keep it there long enough to react. With tight cracks, it can be difficult to get the grout to travel in the crack, but once you get it there it is good to go. With wide cracks or high flow leaks, getting to the right place is easy, but keeping it there long enough to set up can be challenging.

You can use oakum to control grout and keep it where you want it in the crack or joint. Remember we are doing the injection work to stop the flow of water, so let’s make the least amount of holes possible in the concrete. But what does that have to do with oakum? Cracks are irregular, and often have sections that are wider in some sections. When this wider area is at the surface it can allow an easy escape path for a grout under pressure. That means you are wasting grout and not getting it where it needs to be, deep in the crack. Sure, if you have raw resin coming out of the crack you can just wait for it to cure. Once cured you cannot reinject that packer, so it is best to surface seal that crack and stop or slow down the loss of grout. This allows you to continue effective pumping into the crack or joint.

If the crack or joint is wide, grout impregnated oakum can be packed in place. While messy, this is the equivalent of finger painting with chemical grouts and is an easy process.

If you're thinking "I have rags, I don’t need oakum", think again. Oakum is stronger, can be pulled apart into just a few fibers if needed, and can be stuffed into very tiny defects where rags cannot fit.

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A large Mid-Western aluminum manufacturer was losing water from all of its quenching tanks. Losing 3 million gallons in half a year can be expensive, not to mention the massive effect that volume of water can have on soil and the structures it supports. So, they reached out to one of their trusted maintenance contractors, who in turn came to Alchemy-Spetec for guidance on how to efficiently mitigate the leaks with minimal downtime. 

Powerful Polymer

After consulting with Alchemy-Spetec, the contractor 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 holes.
2. Flush debris out of the holes with water.
3. Install the injection port.
4. Flush the crack with water.
5. Inject the resin.

Rapid Results

The crew repaired leaks in one tank at a time with no manufacturing delays. This meant no production interruption. The work was done at a fraction of the cost of replacing the tanks.

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Like with most issues, there is no one final answer, but let’s weigh the pros and cons. An easy one is cost: two-component urethanes are significantly more cost-effective than a single component IF you already have a rig to properly handle them. Keep in mind, not many leak seal contractors typically have a rig.

Speed: let’s talk reaction time. While the single component products can have their set time field adjusted, two-component products will almost always react faster. This is helpful when you have gushing leaks, but often you want to give your grout a longer time to migrate and permeate before they react to ensure you get the whole leak. Remember, 99% waterproofed is 100% leaking.

Both types of grouts are isocyanate-based and are closed celled. They both are highly resistant to chemicals, and neither are UV stable. The two-component grouts are always hydrophobic whereas the single component can be either hydrophobic or hydrophilic. In general, most two-component urethane grouts are rigid or semi-rigid. On the other end of the spectrum, single component polyurethanes can be a gel, a flexible foam, a semi-rigid foam, or even a rigid foam.

So, with all that said, single component foams are the traditional choice for leak seal. When it comes to crack and joint water mitigation, flexibility is key and that rules out most of the two-component foams. When we look at curtain grouting, both can be very effective and there can be a substantial cost saving when it comes to two components. But a downside of using two-component is the shorter set time and thus less travel.

In summation, for leak seal, single component grouts can do everything that is needed and are the typical grout of choice.

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Newcomers to urethane grouts often cut their teeth on these two terms, but the industry in general struggles with the understanding of what they are, and when to use hydrophobic vs. hydrophilic polyurethane grouts. So, I will cover the differences and then point out what I feel is a much more important conversation about polyurethane chemical grouts.

Hydrophobic

• Cured States: Rigid, Semi-Rigid, Flexible Foam
• Reaction: Requires Water
• Requires Accelerator: Yes
• Elongation: None to 100%
• Wet/Dry Cycling: Unaffected
• Adhesive Bond: Good
• Pumped and Handles as: Single Component

Hydrophilic

• Cured States: Flexible Foam or Gel
• Reaction: Requires Water
• Requires Accelerator: No
• Elongation: None to 300%
• Wet/Dry Cycling: Can Dry Out
• Adhesive Bond: Superior
• Pumped and Handles as: Single Component

Somehow, the industry has erroneously assumed hydrophobic means: "fears water and pushes it away". While at the same time assuming hydrophilic means: "loves water and draws it in". There are some truths in these statements but they are only the core and are wrapped in misconceptions.

Misconception One: Water Loving and Water Fearing

Both grouts require water to activate and yes, the hydrophilic grout can incorporate more of the water into its cell structure, but both grouts will push water away when they have reacted with enough water to polymerize.

Misconception Two: Hydrophilic Grouts Dry Out and Shrink Without Water

A more accurate statement would be that cured hydrophilic urethane grouts can dry out and shrink in an arid environment. Concrete normally has a relative humidity of around 60% which will keep a hydrophilic foam hydrated. Soils can vary in their relative humidity but most often have enough moisture not only to keep a hydrophilic grout hydrated but also enough to polymerize a hydrophobic grout without the need for added water.

Misconception Three: Hydrophilic Grouts Have Better Adhesion

It is 100% true hydrophilic grouts have better adhesion in ASTM lab testing, and I did just list them as having superior adhesion. But, in my twenty-plus years in construction, I have never seen a grout job performed under laboratory conditions. Adhesion requires a clean surface for bonding. During crack injection, surface prep is a water flush in a crack we cannot see. So clearly it would be silly to believe we have a pristine surface inside the crack to adhere to. So yes, in a lab, hydrophilic grouts adhere to concrete better than hydrophobic grouts. In situ, both have a weak adhesive bond and both rely on their compressive and mechanical bonds much more than on an adhesive bond.

So, it's important to understand there is much more to grout selection than just hydrophilic and hydrophobic. I would estimate around 60% of chemical grouters only chemical grout a few times year. This can make product and methodology selection very difficult. That is why I am here with the Alchemy-Spetec team to help navigate you through these critical nuances. Call us at 404-618-0438 for technical assistance!

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Municipalities across North America have widespread problems with Inflow and infiltration (I&I). Inflow is in reference to stormwater that invades sewer systems. Infiltration is in reference to groundwater infiltrating manholes, lift stations, pipes, and other sanitary system components. While there are a few solutions on the market for mitigating inflow, this article is primarily focused on mitigating infiltration with polyurethane grout.

What are Sanitary Sewer Overflows (SSOs)?

According to EPA.gov, sanitary sewer overflows (SSOs) can be found all over the country and pose many dangers to public health. They estimate there are at least 23,000 - 75,000 SSOs per year in the United States alone. Because SSOs contain raw sewage they carry bacteria, viruses, protozoa (parasitic organisms), helminths (intestinal worms), and inhaled molds and fungi. Because of this, they may cause diseases ranging in severity from mild gastroenteritis (causing stomach cramps and diarrhea) to life-threatening ailments such as cholera, dysentery, infections hepatitis, and severe gastroenteritis.

Massive Amount of Funds in Place for Sewer & Stormwater Infrastructure Repair

Thankfully, hundreds of billions of dollars are budgeted for addressing these issues according to EPA.gov. The CWSRF (Clean Water State Revolving Fund) was created by the 1987 amendments to the Clean Water Act (CWA) as a financial assistance program for a wide range of water infrastructure projects. This program is a key relationship between the EPA and states that replaced EPA's Construction Grants program. States now have the ability to fund a range of projects that address their urgent water quality issues.

A Simple Plan for Mitigating Sanitary/Stormwater System Infiltration

The grouting plan shown below provides the highest return on investment:

1. Inspect lift stations and manholes.
2. Identify obvious and large leaks.
3. Point repair with polyurethane grout.

Typically, a two-person crew can quickly mitigate 10-30 gallons per hour in less than a day. Just this one day’s work will usually equate to $30,000 a year in savings depending on local treatment costs. For more information on mitigating infiltration with polyurethane grouts, call the Alchemy-Spetec technical support team at 404-618-0438 today.

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One of the most common questions I get about leak seal grout is along the lines of "Can I do this or that? Will it work?". I get this type of question regularly because every job is very unique and there is no one precise grouting procedure that fits everything. Let me introduce you to a term I love to use: exploratory grouting. This is the phase in which you are trying various methods until you find one that works for your particular application. While this just sounds like guesswork, it is very far from that.

So, I have come up with a short three-item list of the things you should not do while chemical grouting with urethanes:

1. Do not eat the grout!
2. Do not get the grout in your eyes!
3. Do not add water to the grout before pumping it. (Actually, there are rare times you do this.)

If you do not break those three rules, your work falls under exploratory grouting. We have a standardized leak seal crack injection procedure that will maximize your result (in a laboratory setting). But concrete restoration does not happen in a laboratory. Start with the procedure, but understand that the procedure is written for the spirit of what we are trying to accomplish. It is not written in stone (as long as you're following the three rules I have listed above).

Pro tip: Number one, do not eat the grout, seems like a no-brainer but it exists because we had a call from someone saying, "My worker ate your grout". 

In summation, remedial waterproofing is often an explorative process and can require on-the-fly adjustments. Setting expectations, maintaining open communication with all involved parties, and attention to detail are essential to making the waterproofing process efficient and successful. Here at Alchemy-Spetec, we have a wealth of experience navigating all types of waterproofing projects. We look forward to assisting you with your specific needs.

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Do you know that leak that returns every year no matter how much hydraulic cement you put on it? Why not make this next time the last time you have to mess with it? Polyurethane grouts have some unique properties that allow them to do things concrete cannot. One of the most glaring is its flexibility.

I like to ask the question, "What is the difference between a joint and a crack?" A joint was engineered by humans while mother nature adds her cracks where the engineer did not see the need for one. They allow the concrete the ability to flex a bit as needed. These cracks can be caused by temperature changes, loading, and unloading, or even a difference in the coefficient of expansion of dissimilar materials, like a metal pipe in a concrete wall.

So, as you pick up that bucket of hydraulic cement, ask yourself, "Is this a dynamic leak? Is movement the issue at hand?" More often than not, movement is the issue and the solution is a flexible polyurethane grout. Spetec PUR GT500 and Spetec PUR F400 are two of the main Alchemy-Spetec grouts used in parking garages, elevator pits, and such. Spetec PUR GT380 is the main grout when it comes to sewers, wet wells, and the like. All of these grouts are highly flexible, NSF 61 certified for contact with drinking water, and allow the concrete to move without allowing it to leak.

Another misconception is that a repair material needs to be dry to effectively waterproof a structure. With polyurethanes that is completely wrong. We want and require water present when injecting the urethane grouts.

So, in summary, the best practice is to quit using hydraulic cement in situations where it will fail because of movement. Instead, waterproof once and effectively with a flexible polyurethane grout and be done with it.

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Polyurethane foam was first discovered in 1937 by Dr. Otto Bayer who lived in Leverkusen, Germany. Bayer was a German chemist and was the head of the research group that discovered this new material. His fundamental idea of combining small volumes of chemical substances together to react into a dry foam material was viewed to be an impossibility. But after many trials and difficulties, Bayer eventually succeeded in synthesizing the first polyurethane foam.

Polyurethane was initially used as a cheap replacement for rubber. Widespread use began in World War II when many other materials became scarce. Polyurethane use quickly spread as a key component in many products, from specialized paper to protective military garments to gloss finishes and protective coatings.

In the 1950s, many companies such as DuPont, BASF, Dow, and Union Carbide started producing polyurethane for an even wider variety of applications including adhesives, insulation, and foam upholstery cushions. By the 1960s, polyurethane began being used for grouting purposes as we know it today. Here’s a brief snapshot of the history of polyurethane grouting:

• The 3M Company in the United States and Takanaka in Japan both introduced polyurethane grouts in the 1960s.
• 3M’s product was called Elastomeric Sewer Grouting Compound. As the name indicates, it was intended for use in underground utilities.
• Takanaka’s product was called Takanaka Aqua-Reactive Chemical Soil Stabilizer (TACSS). As the name indicates, it was intended for use in soil stabilization projects.
• In the early 1980s, DeNeef obtained the rights to TACSS and began distributing polyurethane grout worldwide. By the mid-1980s, there were almost a dozen manufacturers of polyurethane grouts.

Alchemy-Spetec CEO Stephen C. Barton started his career pumping 3M 5600 to seal cracks in the Atlanta subway system back in 1985. He was amazed at what it could do back then, and we're all still amazed at what our products do today. Despite still being specified in outdated documents, 3M exited the business many years ago and no longer manufactures the grout. In the last few decades, polyurethane grouting has become a widely accepted method for sealing leaks, stabilizing soil, and lifting slabs.

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Charlie Lerman, a.k.a. "The Grout Geek", is Alchemy-Spetec's Director of Technical Services - Leak Seal Division. The importance of waterproofing became critical to him while serving on nuclear submarines in the U.S. Navy. With decades of experience in construction and leak seal, Charlie commands unparalleled expertise in grouting techniques and water mitigation.

The vast majority of grouting done in mines is cementitious. Only a fraction of it is done with chemical grouts. This is not because of the effectiveness of chemical grout but rather due to their higher cost. Chemical grouts have a long and successful history of use in mines.

Today I want to focus on a fraction of a fraction when grouting in mines: polyurethane chemical grouts. Or as I like to say, the grout for when all else fails.

So let us start with which urethanes are the go-to. The hydrophobic polyurethanes, both one and two-part, typically have better chemical resistance than the hydrophilic polyurethanes, thus they are preferred in mining applications. More often than not a rigid or semirigid grouts are selected as they have a high expansion factor to help minimize costs. Also, mines typically don't need to be 100% water-tight. Rigid polyurethane grouts in a crack or fissure may leak a bit after that crack moves but their ability to fill voids and stop high flows of even cold water make them more popular than their flexible counterparts.

Polyurethanes are normally used in high flow situations, used to shut off flows so cementitious grouting can continue, and in high salinity environments where sodium silicates cannot be used. They are field adjustable and have superior characteristics to most other types of grout, except when it comes to cost. The majority of polyurethanes are NSF-61 approved for contact with potable water, contain no VOCs, are inert when they cure, and only produce carbon dioxide while curing. Lastly, the leak seal pumping equipment is extremely low cost when compared to other mining and grouting equipment. The one Achilles heel of polyurethanes is their temperature resistance. They don't perform well over 165 F and are not fire-resistant, which precludes them in some applications.

In summation, when you need a hail mary for water control in mining, polyurethane chemical grouts come to the rescue at a premium - and they're worth it!

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It's that time of year again. As temperatures drop, take a moment to review this previously posted article packed with cold-weather tips.

There are plenty of leak seal jobs that need to be done in the winter. So let's take a look at those cold-weather markets. We'll also review some special considerations for conditioning leak seal material and equipment. Then we’ll leave you with a few cold temperature leak seal application tips.

Cold Weather Markets

You have a variety of options for seeking jobs that are inside, out of the elements, during the winter months.  Hopefully, these ideas will spark more brainstorming on your part. First up we have tunnels, both pedestrian and vehicle. Tunnels often leak, sometimes significantly enough to result in quite a big job. Aquariums are another possibility. As you can imagine, there are infinite potential leak problems in a structure holding that much water. Other possible large jobs could include mines and water treatment plants (which have plenty of interior spaces with potential leak issues). On the smaller side, there are utility vaults, lift stations, manholes, and elevator pits.

If you’re still up for working outside during the winter months, you’re in luck because concrete contracts during colder weather. The contraction makes cracks open wider. Wider cracks make leaks more apparent to the property owner and make them easier to repair.

Conditioning Materials and Equipment

One important point to understand is that cold weather requires you to make an extra effort to keep your materials and equipment warm. Cold material reacts slower and gets thicker. Be sure to store your materials and equipment in a heated room the night before the job. When on the job site, there are many ways to keep everything warm. Use an enclosed vehicle, like a box truck, enclosed trailer, or pickup truck with a camper top or bed cover. Keep as much material and equipment inside the vehicle as possible when working. Use a portable heater to maintain a warm temperature. You can also use electric pail heaters to keep your resin ready for action.

Remember that it won’t do you any good to heat the resin if you’re pumping it through cold equipment. The cold steel inside the pump and the cold hose will literally suck the heat out of the resin before it gets where it needs to be. This will increase the viscosity, making it harder to mix with the water and it will slow down the reaction dramatically. So don’t neglect the equipment side of the equation!

Cold Temperature Application Tips

If you’re using a product with an accelerator, you may need to use a faster accelerator or increase your percentage. Also, bring lots of oakum. You may have to use more if the cold temperature slows down the material or the contracted concrete has made the cracks wider.

If your job requires you to inject into a structure underwater (and the water’s cold), you can use a technique called twin streaming. In this approach, you hook two valves together in a parallel fashion – then inject warm water along with the resin to kick start it reacting before hitting the cold water.

Conclusion

I hope this overview has helped spark some ideas on your part for finding leak seal work during the winter months. Just remember to keep your materials and equipment conditioned and you should be fine. Have more questions about polyurethane leak seal in cold weather? Call us at 404-618-0438.

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