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.

Want more information on leak seal products and equipment?

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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The warehouse slab/floor repair market can be a goldmine for contractors. Most major metro areas contain endless square miles of warehouse space. That's why we've posted a good number of warehouse floor and slab repair articles on this blog over the years. In this post, we'll introduce and link to the best Alchemy-Spetec warehouse slab repair articles.

Warehouse and Industrial Slab Repair With Polyurethane

One of the hidden dangers a warehouse or industrial property owner and their employees can face is an unstable or sunken slab with a large void underneath.  The last thing anyone wants is injury and/or a lawsuit resulting from an un-repaired trip hazard or worse - a complete slab collapse. The video in the Read More link below depicts a real-time example of a warehouse slab with cavernous voids below and heavy equipment resting on top.  Next, you'll see the slab repair process in action as the voids are filled and the slabs are restored to a safe, stable state with AP Lift foams that support between 7,200 - 14,000 pounds per square foot (depending on the product selected). Click to Watch the Video and Read More.

Repair Unlevel Warehouse Slabs with AP Lift 475

Voids beneath warehouse floors can be filled with AP Lift 475 foam. This product is great for slabs that rock and warehouse floors that have begun to sink. The video in the Read More link below shows an example of the product in action. Inside this warehouse, the floors have begun to rock and are unleveled - which can speed up the wear and tear on valuable equipment. With this powerful polymer and its painless application procedures, unlevel slabs can be repaired at a rapid pace. Take a look for yourself! Click to Watch the Video and Read More.

Repairing Dangerous Sunken Slabs in Warehouses and Factories

Safety is the number one priority for factory and warehouse managers across the country.  Emphasis is most often placed on training employees to wear the right personal protective equipment and observe safety procedures when operating machinery - and rightly so!  In addition, it's also important for management to consider the state of the concrete slab floors. Click to Read More.

Case Study: Waterproofing Warehouse Slabs

In this case study, Charlie "The Grout Geek" Lerman shares a story about waterproofing warehouse slabs. There was a distribution center in North Carolina sitting on land that had a high water table. Eventually, the slabs in this 100,000 square foot building began to accumulate moisture. There were offices next to the warehouse area. The moisture that was seeping through the concrete slabs was first noticed as the carpet in the office area began to get damp. Click to Read More.

Stabilizing Slabs in an Omaha Warehouse with the PolyBadger

Not too long ago, Alchemy-Spetec customer Sudbeck Construction was called in by the property owner because he had noticed four slabs that were shifting up and scraping against a wall when forklifts crossed them. The crew drilled a couple of preliminary holes in the slabs for diagnostic purposes and discovered voids underneath ranging from 12-18 inches in depth. The Sudbeck team injected 35 gallons of AP Lift 430 beneath the slabs to stabilize them. This high-strength polyurethane foam provides a solid, reliable, long-lasting base underneath the concrete to prevent future shifting or sinking. Click to Read More.

Want more information on warehouse floor and slab repair?

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.

Cracks in Concrete Left Unchecked

Although it’s not unusual to find cracks in concrete, they could lead to detrimental structural issues in the future if not taken care of immediately. But why do concrete structures seem to crack so easily? This issue often occurs due to movement caused by thermal conditions and expansive soils.

And over time, you’ll typically see that these concrete cracks can widen and result in water infiltration, and corrosion of the reinforcing steel. The worst-case scenario we want to avoid is the structural integrity becoming compromised. These cracks are not only a bad look, but they can seriously threaten the lifespan of the structure if left unchecked.

A Quick Look at Polyurethanes vs. Epoxies

This naturally leads us to the next important question to answer: how can we fix it? As usual, there are a few methods used to tackle this problem. In this post, we will cover two popular but different methods: polyurethanes vs epoxies. The reality is that both products can work to address cracks in concrete but under very different conditions.

Due to high compressive strengths, Epoxy is used for cracks in need of structural repair. Often, epoxies even have higher strength ratings than the concrete being repaired. This is why they are the best choice for structural cracks.

Nonstructural cracks that are not leaking are rarely addressed for anything other than cosmetic repairs. This brings us to leaking nonstructural cracks. These cracks are often dynamic in nature. Repairing these moving cracks with epoxy can prove difficult and often results in mirror cracking (a process in which the structural movement causes the original crack pattern to reappear in the applied epoxy). Thus it is imperative to repair leaking nonstructural cracks with flexible polyurethane foam. Flexible polyurethane can move with the structure and still maintain a water-tight seal.

Leaking Cracks in a Parking Garage

A few years back I was asked by an engineer to look at a parking garage that had many leaking cracks. It turned out that it was previously "repaired" with epoxy, yet all the cracks and leaks had reappeared. This is a perfect example of why grouters should not use epoxy in leaking cracks. Another common mistake is to use a rigid (rather than flexible) polyurethane in a dynamic crack.

So the simple takeaway is to remember that epoxies are for structural repairs and polyurethanes are for waterproofing.

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The Alchemy-Spetec app now includes a Leak Seal Material Selection Guide, along with the Polyurethane Estimating Calculator.  The Leak Seal Product Selection guide asks you a series of Yes/No questions about your job and then provides product recommendations.  The Polyurethane Estimating Calculator takes the guesswork out of estimating material for Leak Seal, Geotech, and Floor Repair jobs. Here's a step-by-step guide...

Download the Alchemy-Spetec App & Create an Account

1. Download the app.
Search Alchemy-Spetec in your Apple App Store or Google Play Store to install the app.

2. Create an account.
After installing the app, create an account by clicking "Sign Up" at the bottom and following the prompts.

Select a Leak Seal Product for Your Job

1. Tap the three lines in the top left corner to display the application options.  Choose Leak Seal Material Selection Guide.

2. Answer a series of Yes/No questions about your leak seal job.

3. Review the product recommendation screen (and/or click the Start Over button at the bottom to begin again). Call the Alchemy-Spetec support squad at 404-618-0438 for more guidance specific to your project.

NOTE: You can also access the Leak Seal Material Selection Guide via this red button in the top right corner of our website home page...

Estimate Material for Your Leak Seal, Geotech, or Floor Repair Job

1. Tap the three lines in the top left corner to display the application options. Choose Material Estimation Calculator, then choose Geotech (Slab Lifting & Void Fill), Leak Seal, or Floor Repair for your job type.

2. Select the measuring system you want to use.

3. The Slab Lifting calculator appears by default. You can switch to the Void Filling calculator by clicking the button at the bottom right. Choose your product and fill in the square feet of your slab, plus the inches it has settled (or inches of void if using the Void Filling calculator).

4. View the recommended material quantities. Call the Alchemy-Spetec support squad at 404-618-0438 for more guidance specific to your project.

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