A general contractor working for a school district in Buffalo, New York was asked to lift and level around 550 feet of sidewalk slabs at a local high school. The general contractor called in slab lifting specialists Gernatt Spray Foam to get the job done. Since sunken slabs often result in trip hazards, getting the job done quickly and permanently was a top priority.

Powerful Polymer

The slab lifting crew showed up on the scene armed with AP Lift 435 high-strength polyurethane and several Jack Attack devices.

Painless Procedure

Gernatt Spray Foam leveled all 550 feet of sunken sidewalk slabs with total precision. They performed lifts ranging from 0.5 to 6 inches, depending on the slab. In some cases, they lifted with polyurethane only and in others, they raised the slab with the jacking devices before injecting the polyurethane underneath.

Rapid Result

The entire job was completed in only two days. The general contractor and school administrators were both amazed at the efficiency and surgical precision of the polyurethane slab lifting method.

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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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On October 26th - 28th, Contractors across North America traveled to Alchemy-Spetec HQ in Tucker, GA for a thorough education in Slab Lifting, Soil Stabilization, the Deep Lift® process, equipment, and applications. They received hands-on training from a technical staff with decades of on-the-job experience.

This three-day geotech bootcamp featured presentations and demos on the following subjects:

• Geotech Product Line Overview
• Geotech Applications & Case Studies
• PolyBadger® Demo & Training
• Estimating & Quoting Jobs
• PMC Pump Demo & Training
• Leak Seal Issues on Geotech Jobs
• Ground Penetrating Radar Demo & Training
• Slab Lift Rig Demo & Training
• Competing Geotech Techniques
• PolyShark® / Soil Stabilization Demo & Training (On-Site)
• Deep Lift® Demo & Training (On-Site)

All of us here at Alchemy-Spetec would like to thank everyone who participated! and extend an invitation to those who missed this event to sign up below for notifications on future training programs.

Alchemy-Spetec's AP Gel Patch is a polymer modified, cementitious patching material. This product is ideal for the structural repair of deteriorated concrete. It's for use on above or below grade structures. 

Uses

• Structural repair of deteriorated concrete.
• For use on above or below grade structures.
• Can also be used on vertical or overhead surfaces.

Advantages

• Superior adhesion.
• Polymer modified.
• Similar modulus of elasticity to concrete.
• Extremely low shrinkage.
• Vapor permeable.
• Resistant to freeze/thaw cycling.
• Easy to apply and finish.
• May be built up to 2 inches overhead in one application.
• Contains a corrosion inhibitor.
• Coatings may be applied after 72 hours.

AP Gel Patch is available in 50 lb bags.

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As the weather gets colder, contractors in some regions will need to prepare their slab lifting rigs for storage during the off-season. We're providing step-by-step instructions for that procedure in this article.

Please Note:

• You will notice that more care is given to the A-side of the system, this is normal.
• This procedure assumes you are using a PMC pump.

Prepping a Slab Lifting Rig for Winter Storage

1. Remove and clean the A and B stick pumps. Clean the exterior of the pumps with brake cleaner to remove as much residual resin and polyol as possible.
2. Place the A-Side transfer pump into a 5-gallon pail of the AP Flush 121.
3. Remove the recirculation hose from the A-Side drum and place it in a purge pail.
4. Open A-Side inlet valve and recirculation valve on your PMC machine.
5. Slowly open the air valve on the A-Side transfer pump to start introducing the AP Flush 121 through the A-Side of the machine.
6. You will notice iso material being pushed out of the recirculation line into the purge pail. Continue to pump AP Flush 121 through the system until it comes out of the recirculation line clear, with no added coloring or debris.
7. Shut the air supply feeding the transfer pump. This will stop all flow of material.
8. Un-cap the A-Side of the PMC whip hose. Once un-capped, place the hose into the purge pail.
9. Close the recirculation valve on the A-Side of the PMC machine.
10. Slowly open the air valve on the A-Side transfer pump to start the flow of AP Flush 121 through the heated hose.
11. You will notice iso material being pushed out of the whip hose into the purge pail. Continue to pump AP Flush 121 through the system until it comes out of the recirculation line clear, with no added coloring or debris.
12. Now that this process is complete, the A-Side has been completely cleaned of any iso material.
13. Remove the A-Side transfer pump from the pail of AP Flush 121 and place it into a 5-gallon pail of AP Lube 190.
14. Slowly open the air valve on the A-Side transfer pump to start introducing the AP Lube 190 through the A-Side of the machine. Continue to pump the AP Lube 190 until you have pure and clean AP Lube 190 coming out of the end of the whip hose
15. Place the B-Side stick pump into a separate 5-gallon pail of AP Lube 190.
16. Slowly open the air valve on the B-Side transfer pump to start introducing the AP Lube 190 through the B-Side of the machine and heated hose. Continue to pump AP Lube 190 through the system until it comes out of the end of the whip hose, with no added coloring or debris.
17. Once the entire system is full of clean AP Lube 190, slowly start to recirculate the AP Lube 190 through the entire system. When doing this, it is best to let the PMC machine cycle while recirculating the AP lube 190.
18. Once all these steps are complete, close the air on each transfer pump and re-cap the heated PMC whip hoses.

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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.

In this blog post, we will share some tips for stabilizing soil in cold weather. The two main points to remember are – make sure the ground isn’t frozen and condition your material and equipment properly.

Do Not Attempt Soil Stabilization Work When the Ground is Frozen

If you’re considering soil stabilization in cold weather, the first step is to make sure that the water table isn’t frozen. Iced earth is not permeable enough for proper mixing of resin and soil. If you attempt to proceed with frozen soil, you’ll just be wasting your material. Best to wait it out in that case.

Properly Condition Equipment and Materials

For optimal results, it’s best to store any materials and equipment that are to be used in a heated environment overnight. It’s best to keep your AP Soil 600 above 60 degrees at all times. This is key because cold material reacts slower and gets thicker. The methods you use to condition your material on the job site will depend on the type of vehicle you’re using.

In Slab Lifting in Cold Weather, we described in detail how to condition materials for cold weather if you’re using a rig…

If you have an insulated rig, it should stay around 40 degrees warmer than outside temperatures. Most foam rigs have built-in electric heaters that require an extension cord to a power outlet at the job site or at your facility for overnight storage. Alternately, you could buy an electric radiator heater. Other available heating devices include drum band heaters and heated drum mats (be careful not to scorch the polymers by turning band heaters up too high). For a more DIY approach, you could build a hot box around the material storage area in your rig.

If you’re using pails and a smaller vehicle, we offered tips for that set up in my Polyurethane Leak Seal in Cold Weather article…

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.

Using a combination of the methods described above, you should be able to keep your materials warm enough. In extreme cases when the material gets a bit too cold and thick, you may want to use AP Cat 600 to speed up the reaction time.

Conclusion

As long as the ground isn’t frozen, you should be able to stabilize soil in cold weather.  Just make sure your materials and equipment are conditioned properly.  If you have any further questions, please contact us at 404-618-0438.

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

Contrary to popular opinion, as a contractor, you don’t have to put up your equipment and rigs due to cold weather. There are many jobs to be done and many ways to keep your material conditioned. Use this season to your advantage and gain valuable business.

Cold Weather Markets

Seasonal attractions such as theme parks are a great place to start looking for winter work. Many of these parks (the ones that aren’t in Orlando) shut down for the winter and this is the time they do maintenance and repairs. Think of all the concrete lifting and leveling that can be done.

Factories can be less active in the winter months with production slowing down in many industries. This is a good time for them to do maintenance and floor repairs as well.

Warehouses typically operate year-round, so there is always work available. Warehouse floors are used and abused on a daily basis and will sooner or later need some form of repairs done to keep business running at a steady pace. In addition, many warehouses have dangerous voids beneath their floors that require repair.  

Exterior concrete slabs are still worth considering, even in the cold weather. These slabs experience the most wear and tear from the environment itself (think erosion) and daily traffic. You’ll need to lift concrete slabs before the ground freezes and only after your materials have been thoroughly conditioned.

Conditioning Materials

Your slab lifting equipment probably has built-in heaters and a heated hose. Each brand and model of pump has different sized pre-heaters and different ∆T (∆ = Delta and T = Temperature). This sounds complicated but is actually quite simple.  ∆T is simply the change in temperature.  Let’s say your material has been sitting in a cold trailer all night and the temperature has dropped to 40 degrees F. If the required temperature of your B side material is 120 degrees F, then your pump better be rated with a ∆T of at least 80 degrees. However, if your material is preconditioned to 70 degrees F, then your machine only has to be rated for a ∆T of 50 degrees. As I said, every machine is rated differently based on the size of the heaters. What is important to know is that there are limitations to how much heating your machine can do.

Keeping your materials conditioned in the winter months is a lot easier than it sounds. The main point is to keep your AP Lift products above 60 degrees at all times. Keeping the polyurethane at or above that temperature can be accomplished in a number of ways.

If you have an insulated rig, it should stay around 40 degrees warmer than outside temperatures. Most foam rigs have built-in electric heaters that require an extension cord to a power outlet at the job site or at your facility for overnight storage. Alternately, you could buy an electric radiator heater. Other available heating devices include drum band heaters and heated drum mats (be careful not to scorch the polymers by turning band heaters up too high). For a more DIY approach, you could build a hot box around the material storage area in your rig.

Heat Sink

Another consideration when lifting cold slabs is the heat sink factor. AP Lift products come out of the gun hot and get even hotter as they react. However, cold concrete acts as a heat sink and sucks the energy out of the foam as it starts to react. This can slow down the reaction speed of the foam. If you are pumping into a void, it will have little effect because most of the foam is not in contact with the concrete. If you are trying to lift a slab with little void, it will have more of an effect because more of the foam is in contact with the cold concrete and cold soil. More volume = more energy.

Conclusion

Don’t let common preconceptions deter you from slab lifting in cold weather. As noted above, there is no need to shut down completely for the upcoming winter months if you don’t want to. Opportunities still exist and one of them may just be the job you’ve been looking for all year. There are many ways to keep your equipment and materials conditioned to efficiently work in lower temperatures. Have more questions about slab lifting in cold weather? Call us at 404-618-0438.

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This post is part of the Alchemy-Spetec Contractor Lens series, featuring views, news & case studies written by our customers. This article, written by Brian Dalinghaus of Dalinghaus Construction, contrasts polyurethane slab lifting vs mudjacking (lifting slabs with a mortar-based mixture of "mud" or "slurry"). If you're an Alchemy-Spetec customer and you'd like to discuss writing content for our blog, please send an email to marketing@alchemy-spetec.com today!

Do you have a sinking slab that needs a lift? There are two primary lifting services in the construction industry capable of lifting, stabilizing, and leveling your foundation/flatwork: polyurethane injection and mudjacking.

If you read our blog, keep up with our Instagram, or watch our Youtube channel, then you’ve undoubtedly heard a lot about polyurethane…but not much about mudjacking. 

This is because we tend not to write extensively on services we do not provide – however, in this article, we are going to analyze the 3-key benefits of polyurethane slab lifting over mudjacking:

1. Lighter Weight
2. Smaller Hole Size for Application
3. Faster Cure Time 

What is Mudjacking?

Mudjacking is the lifting or leveling of a structure, driveway, or slab of concrete by pumping a mixture of slurry (with incredibly high pressure) underneath a sunken slab.

Polyurethane Weighs Less

Polyurethane weighs 2-4 pounds per cubic foot. Mud can weigh as much as 100 pounds per cubic foot. Weight is important because it can act as an anchor, sinking an already settling ship.

Polyurethane can help stabilize soil by adding rigidity – mudjacking simply packs on more weight. Yes, mudjacking is extremely effective at lifting settled flatwork and is attractive because of its relatively cheap cost, but it is not a long-term solution.

The mud will eventually settle into the expansive soil.

Polyurethane floats on expansive clays and only settles when the soil beneath it gives way. Polyurethane is lightweight, dense, and incredibly strong.

Polyurethane relies on the expansive pressure for the lift. Mudjacking relies on installation pressure.

Fun Facts with Brian – Polyurethane expands kind of like shaving cream after leaving a can, allowing it to fit perfectly into crooks and crannies as it balloons outward.   

Polyurethane Utilizes Smaller Application Holes

Polyurethane and Mudjacking follow the same three-step system: Drill, Pump, Patch.

The biggest difference in the system itself is the size of the application hole.  

Poly & Mudjacking’s Three Steps –

• Drill – Drill into the concrete (often in a grid pattern)
• Pump – Void fill the hole with a slurry application gun
• Patch – Patch holes and color code the concrete to match

The polyurethane injection site hole is only 3/8" to 5/8” (depending on the type of injection), whereas mudjacking injection holes are 2 to 3 inches.   

Unless you want your driveway looking like a Dalmatian, we suggest utilizing polyurethane. The patched injection sites are far less noticeable.

In addition, mudjacking can prove a bit of a mess, with excess slurry slurping out of cracks and crevices. The polyurethane foam, once dry, is easy to square off with a boxcutter.

Polyurethane Cures Faster Than Mud

Polyurethane cures quickly, solidifying up to 90% full strength in 15 minutes. In contrast, mudjacking slurry shot underneath the slab is never exposed to sunlight (thus taking a much longer time to cure).    

The truth is: slurry can take several days to a week to dry. And, fun fact about concrete, it never really fully cures.

Why Choose Polyurethane Injection? 

Polyurethane is lightweight, easy to install with little chance of a mess, and cures incredibly fast. Mudjacking, on the other hand, is not a permanent fix and can sink your flat-work.  

If you live in Southern California or Central Arizona and would like a FREE void fill inspection, click the link below -

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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?