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 Despite still being specified in outdated documents, 3M exited the business many years ago and no longer manufactures the grout.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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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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For most of my 36 years in the chemical grout industry, I have listened to people refer to chemical grouts as temporary leak repair in the same manner they mention a band-aid in stopping bleeding. Many of these same persons also say that stopping water leaks with chemical grouts is like “smoke and mirrors”, implying some sort of black magic. I must state that they are wrong on both counts.  

The mechanism by which chemical grouts stop leaks is based upon basic textbook polyurethane and acrylic chemistry. It may seem a little mysterious because most of the reaction takes place out of sight within or behind the concrete structure, but the reactions can be duplicated in the laboratory for doubters to see. As for durability and permanence, the oldest of the chemical grout manufacturers have documented case histories that are now 50 years old. I would call these permanent repairs when compared to some leak seal alternatives.

It is true, however, that for every success story I offer, someone will bring up an instance where chemical grouting did not work. Upon careful examination, these failures are almost always due to the products being incorrectly specified or installed. The biggest problem I have encountered that leads to premature failures occurs when the contractor fails to pump grout into a crack or joint until total rejection occurs. That is the point where the crack will accept no more grout. Correct product selection and installation in consultation with the manufacturer are essential to a successful long-lasting leak sealing project.

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Infiltration is Draining Your Budget

In Sealing Water Infiltration in Leaking Joints, Inverts and Manholes, we identified strain and efficiency issues treatment plants undergo when groundwater infiltrates city collection systems. These common issues lead to large expenses that accumulate over time if left unchecked. A plan to minimize the damages must address the specific scale of the problems, the age and condition of your overall infrastructure, and your budget. A trusted, experienced team of consultants will prove invaluable as you navigate these uncharted waters.

Effective Manhole Infiltration Repair

According to the EPA, there are over 20 million manholes in the US. Water is infiltrating this aging infrastructure on a daily basis. If you're a municipal administrator or manager, you may already have sent in crews to eliminate the leaking with common waterproofing techniques such as applying hydraulic cement or epoxy coating. But these methods are not always 100% effective in the long term.

One of the most comprehensive ways to completely eliminate all groundwater infiltration in manholes is to encapsulate the structure using curtain grouting techniques. Specialty subcontractors utilize this technique by drilling through to the outside of the wall and injecting highly expansive polyurethane foam into the voids and soils behind it. The expansive chemical grout permeates the soils thanks to its low viscosity and creates a permanent water barrier that can fully encapsulate the manhole if necessary.

When to use Curtain Grouting

We've discussed sealing joint and penetration leaks in previous blog posts, but what if you have numerous leaks, are concerned about voids in the soil, or are repairing a brick manhole? Curtain grouting is especially useful for brick or block manholes that are made up of hundreds of joints and seams where water has many opportunities to penetrate the structure. Encapsulating the structure will polyurethane not only stops infiltration but also fills soil voids. Curtain grouting is just one technique among a handful of methods specially designed for eliminating groundwater infiltration. We recommend getting in touch with our Leak Seal Director of Technical Services, Charlie Lerman, for a free consultation to determine what leak seal methods are best for your infrastructure. Call him today at 404-618-0438. 

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In the United States, tilt-up construction is very common and the resulting joints are typically caulked. The vast majority of the time that is totally sufficient. But what about the joint you find yourself recaulking every six months to a year? While not the norm, they can be a real hassle and a thorn in your side. Enter Spetec PUR F400 and welcome to this blog post!

Spetec PUR F400 is a flexible hydrophobic polyurethane grout. Oakum is a fibrous jute rope that we soak the F400 in and then use to pack the wetted joint from the bottom up. This is a messy but simple process that leaves you with a full-depth seal/bond as opposed to the typical ¼” bond that is standard when caulking. The excess foam can be cut back and caulked to match the existing joints. Caulking is also required on the exterior as F400 is not UV stable, so the caulk protects the F400 from UV and makes the joint cosmetically match the other joints.

The same grout/oakum procedure described above can also be done for joints that are in constant submersion. Standard urethane caulk is not designed for constant submergence and while polysulfides are, they still can have problems with it. F400 is unaffected by wet, dry, wet/dry, or constant submerged environments.

These repair procedures can be applied to pipe penetrations as well. The "oakum soakum" method, as it's commonly known, is a tried and true methodology. But it is also one of the simplest methods for polyurethane chemical grout installation. I equate it to fingerpainting with chemical grouts.

Every grouting job has its unique challenges. Alchemy-Spetec's industry-leading tech support team is here to help! Call 404-618-0438 for assistance with your leak seal job today!

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Treatment plants undergo massive strain and efficiency issues when groundwater infiltrates city collection systems. These common problems lead to large expenses that can accumulate if left unchecked. Identifying the root causes and creating a plan to minimize the damages will be dependent on the scale of the problems, the age and condition of your overall infrastructure, and your budget. Having a trusted, experienced team of consultants will prove to be invaluable as you navigate these uncharted waters.

What is Groundwater Infiltration?

Groundwater Infiltration is an industry term referring to groundwater improperly entering a sanitary sewer wastewater system. This water, which normally drains deep into the ground or is routed to storm drains, ends up being treated. This costly treatment will eat away at your already limited budget while also taking up precious capacity within your collection system. Some common ways groundwater can enter sewer pipes (interceptors, collectors, manholes, or side sewers) are through cracks, leaky pipe joints, connection failures, and poorly maintained manholes.

You may have groundwater infiltration issues if you notice any of the following signs:

1. Your pipes are backed up during rainy seasons. This is often a good indicator of an unforeseen infiltration issue. During the next heavy rain, determine if your manholes are spilling wastewater onto local roadways or fields. This may be a good indicator that you have a surplus of groundwater infiltrating your wastewater systems.
2. Your lift station pumps running continuously or cycling frequently. There may be an issue at hand if your lift station pumps run continuously for a long time after a typical rain event, or if your pumps start and stop frequently. Either event is likely happening because groundwater has entered your sanitary sewer system and is overloading your treatment centers.
3. You can measure significant spikes in flow rates. As you measure and evaluate the effectiveness of your wastewater treatment plant during rainy or high groundwater conditions, readings that return abnormal spikes in inflow likely indicate an I&I issue. While small amounts of infiltration are to be expected, large spikes rarely happen unless there is a significant infiltration issue at hand.

6 Methods to Quantify Infiltration Issues

The warning signs noted above are helpful but indicate basic symptoms only. Once you’ve suspected that groundwater is infiltrating your system, there are 6 proven methods for capturing important data to determine the next course of action. These methods must be performed by a reputable engineering firm or a survey team.

1. Sanitary sewer flow monitoring
2. Manhole inspections and 3D technology
3. Smoke testing
4. Dye testing
5. Pipe inspection/closed circuit television inspection (CCTV)
6. Private property inspections

Cost-Effective and Proven Solutions to Stop Infiltration Immediately

These groundwater infiltration points can be permanently sealed off with crack/joint injection & curtain wall procedures using water-activated polyurethane foam. Pressure injection of these liquid polyurethane resins forces the material into leaking cracks, joints, or voids behind leaking structures. After the polyurethane injection is complete, the polyurethane resin rapidly reacts with water to form a watertight seal.

These leaks can be repaired with a small crew of about three people. A repair crew this size typically averages about two manholes per day (depending on manhole size and proximity). On average, curtain wall grouting a 4-foot diameter x 8-foot tall manhole requires 5 gallons of Spetec PUR HighFoamer. On average, treating joints and pipe penetrations on a 4-foot diameter x 8-foot tall manhole requires 2.5 gallons of Spetec PUR GT380.

• Failing Sewer Pipe Joints: Groundwater rising and falling puts hydrostatic pressure on pipe and manhole joints, causing them to fail. Point grouting consists of driving injection pipes to the points of failure and injecting a resin such as Spetec PUR HighFoamer. The resin expands and cures quickly to seal off the leaks and fill voids in the soil. Filling the voids with a grout like Spetec PUR HighFoamer also reduces the hydrostatic pressure on the joints. The grout also permeates the soil and increases the load-bearing capacity which can prevent future misalignment of the pipes.
• Pipe and Manholes Inverts: For many years, inverts have been repaired with hydraulic cement. But hydraulic cement fails if there is structural movement over the long-term, and thus leaking cracks/joint return. While hydraulic cement is cheap, repeating the repair process over and over is very expensive and means more confined space entries. Injecting the joints and inverts with a flexible polyurethane grout will provide a long-term repair, often longer than the expected service life of the manhole. Spetec PUR GT380 is the gold standard for these types of repairs, but at times a hydrophobic grout might be needed and thus Spetec PUR F400 would be the grout of choice. With the F400 different reaction times are possible by adjusting the percentage of GEN ACC Accelerator.
• Precast Manhole Joints: A factory-trained specialty contractor can seal precast manhole joints using Spetec PUR GT380. It is a hydrophilic polyurethane material that cures to form a gel or a foam. Because it's a single-component material, you can install it easily without the need for mixing. It can easily penetrate joints before it eventually cures into place, thanks to its low viscosity. Spetec PUR GT380 is a durable, long-term sealing solution that holds up against the harsh sewer environment.

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