This post is part of the Alchemy-Spetec Contractor Lens series, featuring views, news & case studies written by our customers. This article was written by Brian Dalinghaus of Dalinghaus Construction. 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!

Why Do Concrete Slabs Become Uneven?

Concrete slabs such as sidewalks, driveways, and patios, usually become uneven for one of the following reasons:

• Expansive soil – Expansive soil is clay-rich and for this reason expands as it soaks up moisture, and then shrinks as it loses moisture and dries out. This swelling/shrinking – which can be caused by drought/non-drought periods – causes movement in the soil under the slab, and will often cause a slab to become uneven over time.
• Erosion under the slab – Some types of soil are prone to erosion and if there’s poor drainage under the slab, this could cause voids to form and an uneven slab eventually.
• Soil not tamped down – Soil always needs to be properly compacted before anything gets placed or built on top of it, including concrete slabs. If this isn’t done, the slab could settle into the soil and end up uneven.
• Tree roots – We’ve all seen examples of tree roots pushing up on a slab and causing it to become unlevel.
• Dead leaves decaying leave voids – Leaves and other organic matter should be removed from the soil before a concrete slab is poured. If this isn’t done, voids could form under the slab. If the slab sinks into the voids, it will become uneven.

Uneven Concrete Slab Repairs Using Polyurethane Foam Injection

Fortunately, an uneven concrete slab can be repaired (i.e, leveled) in just a few hours using polyurethane foam injection, a waterproof material that’s injected under the slab in order to level it. Polyurethane foam injection can lift and level sidewalks, driveways, patios, pool decks, and more.

The general polyurethane foam injection procedure to perform concrete slab repairs is as follows:

• Dime-sized holes are drilled into the affected slab.
• A nozzle is inserted through the holes and the polyurethane foam is injected under the slab.
• The foam immediately begins to expand, fill any voids, and raise the slab.
• The holes are patched using a compound that matches the color of the concrete.
• Fifteen minutes after the repair is complete, the slab is ready for use.

Is Polyurethane Foam Better Than Mudjacking?

Yes, we believe polyurethane foam injection is better than mudjacking. Mudjacking is an older method for leveling an uneven concrete slab. Today, most concrete leveling jobs are done using polyurethane foam injection for the following reasons:

• The mudjacking slurry used to raise the slab is heavy because it contains cement, sand, soil, etc. Because of this, it has the potential to make the problem even worse because the slab might have become uneven due to weak soil that is unable to support it. If so, adding more weight to the soil in the form of a cement slurry isn’t going to help.
• The mudjacking slurry is prone to erosion if there’s poor drainage under the slab.
• The holes used to inject the mudjacking slurry under the slab are at least 2 inches wide. Compare this to the dime-sized holes used with polyurethane foam injection.
• Mudjacking is a messy process that takes 2-3 to dry and harden. This means downtime.

Yes, mudjacking is still being done today. However, we view it as a temporary fix, at best.

Are Concrete Slab Repairs Better Than Replacing The Slab?

Unless the concrete slab is severely damaged, yes, lifting the slab via polyurethane foam injection is better than digging up and replacing the slab. Concrete leveling using polyurethane foam is a quick procedure taking usually no more than a few hours and then the slab is ready for use. Pouring a new slab and then waiting for it to dry and harden takes time. Replacing a slab is also more expensive. Therefore, severely damaged slabs are typically the only cases that are not a good fit for leveling with polyurethane.

How Much Do Uneven Concrete Slab Repairs Cost?

The cost to fix an uneven concrete slab using polyurethane foam injection depends on where you live and the size of the affected area (this determines how much lifting foam is needed).

How To Help Prevent Concrete Slabs From Becoming Uneven

You can help prevent a concrete slab – such as a sidewalk or driveway – from becoming uneven, by doing the following:

• Make sure the soil is adequately tamped down before the slab gets poured on top of it.
• Ensure that any organic material (such as leaves) is removed from the soil before the slab gets poured.
• Make sure there’s good drainage under and around the slab.
• Keep trees with invasive root systems away from the slab.

If you have an uneven concrete slab that needs to be lifted and leveled (and you’re in the Dalinghaus Southern California and Arizona service area) click here to contact Dalinghaus today and schedule an evaluation.

Want more information on uneven concrete slab repair?

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 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. Alternatively, 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.

Want more in-depth info on slab lifting?

The ideal polyurethane foam for filling voids under a driveway, AP Lift 430 works in a variety of wet, dry, or harsh conditions, can support up to 7,200 lbs per square foot, and will cure to 90% full strength in 15 minutes. This two-component, high-strength, high-density, hydro-insensitive structural polymer weighs 2.75 – 3.25 pounds per cubic foot. When injected, polyurethane will conform to the shape of the void more accurately than other materials such as cement grout. And, unlike cement, it won't sink over time.

Watch the video below for a real-time example of polyurethane void fill with AP Lift 430. The structural stability of this driveway is under threat due to a very wide void ranging from one to two feet deep. Since the supporting soil on one side of the slab has entirely eroded away, it was possible to capture this process very clearly on video.

Watch the process closely and then call 404-618-0438 to be connected to your technical support representative for any follow-up questions. Alchemy-Spetec offers the most experienced tech support team in the industry. Contact us today for assistance on your next job!

Want more info on geotech products and equipment?

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

Prepping a PolyBadger for Winter Storage

1. Establish power to the cabinet and heat the hose (A heater, B heater, and hose) to the target temperature of 130° F.
2. Introduce material to the cabinet.
3. Turn the air supply on and recirculate to heat up the ISO and resin.
4. Once the PolyBadger is up to temperature, turn off the air supply and remove the airlines from the stick pumps.
5. Remove the supply and the recirculation line from the A-side stick pump.
6. Drain all the remaining material from the pump and clean it with brake cleaner.
7. Place the stick A side stubby stick pump into a 5-gallon pail of the AS Pump Flush.
8. Reconnect the supply line and leave the recirculation line to drain in a purge pail.
9. Repeat steps 5-8 on the B-side stick pump.
10. Reconnect the air supply to the stick pumps, hold the return lines in a purge pail, and slowly open the air valve on the stick pumps.
11. You will notice material slowly 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 color or debris.
12. Shut the air valve supplying the stick pumps. This will stop the flow of material.
13. Reconnect the recirculation lines to the appropriate stick pump and tighten.
14. Turn the recirculation pump valves to supply the hose.
15. You can remove the Handi Gun or leave it on for this stage, holding the hose in the purge pail. Turn on the supply valves on the end of the hose just before the Handi Gun. Slowly open the air valve on the stick pumps and pull the trigger on the gun.
16. You will notice material slowly pushed out of the hose line into the purge pail. Continue to pump AP Flush 121 through the system until it comes out of the hose line clear, with no added color or debris.
17. Shut the air valve supplying the stick pumps. This will stop the flow of material.
18. Remove the stick pumps from the AS Pump Flush. (Make sure to mark your pails A and B for future use).
19. Insert stick pumps into AP Pump Saver 195. (Make sure to mark your pails A and B for future use)
20. Push the AP Pump Saver 195 through the hose line. You will notice the AS Pump Flush slowly pushed out of the hose line into the purge pail. Continue to pump AP Pump Saver 195 through the system until it comes out of the hose line clear (you will notice a thick, clean fluid).
21. Turn off the supply valves on the hose just before the Handi Gun.
22. Disconnect the air supply to the stick pumps.
23. Move the hose supply valve into the recirculation position to depressurize the system.
24. Shut off supply valves to the cabinet.
25. Turn off heat zones.
26. Turn off the main disconnect.
27. Remove residual grease from interior cabinet pumps.
28. Replace with new grease.

Want more information on the PolyBadger?

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 AS Pump Flush.
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 AS Pump Flush 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 AS Pump Flush 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 AS Pump Flush through the heated hose.
11. You will notice iso material being pushed out of the whip hose into the purge pail. Continue to pump AS Pump Flush 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 AS Pump Flush 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.

Want more information on geotech products and equipment?

Soil testing equipment is extremely helpful for planning slab lifting and soil stabilization work. Contractors use ground penetrating radar systems and dynamic cone penetrometers to get a sense of soil conditions before they drill their first hole into a slab or push their first injection pipe into the ground.

Deep Look™ Ground Penetrating Radar

The Deep Look™ wireless ground penetrating radar collects data from hundreds of thousands of pulse reflections each second to help contractors identify objects below ground. The triple-frequency antenna design provides higher-resolution imaging than conventional GRP systems.

Dynamic Cone Penetrometer

The Pagini DPM30 dynamic cone penetrometer is ideal for testing soil strength and density at various depths. The fact that it is exceptionally small means it can be used on sites that are inaccessible to normal machines. A hydraulic pump raises and drops a weight onto a measuring rod, pushing it into the ground. To measure soil strength, the operator counts the number of blows it takes to drive the steel rod in 10-centimeter increments. Good soil requires 10+ blows to drive the rod 10 centimeters. Anything less is typically indicative of weak soil conditions.

Want more info on geotech equipment and repair materials?

The Concrete Leveling Process

Surface erosion, water damage, shrinking from heavy loads, or void spaces in the soil can all cause commercial, industrial, and residential slabs to sink or, in worst-case scenarios, collapse completely. Even without catastrophic collapse, slightly uneven concrete can cause expensive damage to property, vehicles, and factory equipment - not to mention personal injury.

Polyurethane concrete leveling is often the most cost-efficient and durable solution to this problem. A technician simply drills 3/8-inch holes through the concrete surface. Then, injects one of the Alchemy-Spetec concrete leveling polymers with the MixMaster Pro slab lifting gun. As the foam expands, pressure on the underside causes the concrete to lift to its original level position. The slab is ready for traffic 15 minutes after installation. The repair is waterproof and strong enough to support virtually any structure.

Concrete Leveling Case Studies

• Slab Lift for Chinese Railway
• Slab Lifting at a High School in Buffalo, New York
• Contractor Successfully Completes Unique & Challenging Driveway Lift
• Leveling Sunken Slabs in a Pole Barn
• Slab Lift at Seed Sorting Plant

Want more information on polyurethane concrete leveling?

Alchemy-Spetec offers one-hour CE/PDH accredited presentations on polyurethane concrete repair. Presentation topics offered include Leak Seal, Geotech, and Seawall Repair. Here is a detailed overview... 

Leak Seal Presentation

The Specialty Waterproofing with Chemical Grouts presentation covers sealing leaks in structures with the use of polyurethane chemical grout injection materials and techniques. 

• Chemical Grouting Primer
  • History
  • Safety
  • Characteristics
• Utilization & Applications
  • Identifying Applications
  • Selecting a Chemical Grout
  • Epoxy & Hydraulic Cement
• Installation Techniques
  • Crack and Joint Injection
  • Curtain Grouting
  • Oakum Soakum
  • Equipment Overview

Alchemy-Spetec's one-hour CE/PDH accredited Leak Seal presentation is perfect for engineers looking for information on innovative and proven leak seal repair methods for sealing leaks in structures, inflow/infiltration mitigation, and more.

Geotech Presentation

The Geotechnical Applications for Polyurethane presentation explains three types of concrete leveling and soil stabilization materials and applications. 

• Single Component Polyurethane Grout Applications
• Two-Component Polyurethane Grout Applications
• Acrylic Grout Applications

Alchemy-Spetec's one-hour CE/PDH accredited Geotech presentation is perfect for engineers looking for information on innovative and proven geotechnical repair methods for lifting concrete, soil stabilization, excavation support, controlling erosion, and more. 

Seawall Repair Network Presentation

The Seawall Stabilization and Preservation through Permeation Presentation explains and demonstrates how Seawall Repair Network contractors use polyurethane injection resin and surface-applied preservation solutions to stabilize and preserve seawalls and bulkheads. (Seawall Repair Network is a division of Alchemy-Spetec.)

• The Causes of Seawall Failure
• Stabilizing a Seawall
• Preserving a Seawall
• Stabilization & Preservation Through Permeation

Alchemy-Spetec's one-hour CE/PDH accredited Seawall Repair Network presentation is ideal for engineers who are interested in designing superior seawall/bulkhead rehabilitation and preservation solutions. This type of environmentally friendly permanent soil stabilization and seawall preservation can be applied to all types of waterfront infrastructure.

Want info on scheduling a presentation?

Alchemy-Spetec HQ in Tucker, GA

THIS EVENT HAS BEEN CANCELLED

$745 Registration Fee
$665 for each additional participant from
the same company.

Get ready for a thorough education in Slab Lifting, Soil Stabilization, the Alchemy-Spetec Deep Lift® process, equipment, and applications. You’ll get hands-on training from a technical staff with decades of on-the-job experience.

Tuesday, October 4th

• Geotech Product Line Overview
• Geotech Applications & Case Studies
• MixMaster Pro Slab Lifting Gun
• Slab Lift Rig Demonstration

Wednesday, October 5th

• Pump Demos & Training
• PolyShark® / Soil Stabilization
• Deep Lift® 
• Ground Penetrating Radar

Thursday, March 31st

• PolyBadger® Mobile Slab Lifting System
• Estimating Material for Jobs

THIS EVENT HAS BEEN CANCELLED

Alchemy-Spetec HQ in Tucker, GA

THIS EVENT HAS BEEN CANCELLED

$745 Registration Fee
$665 for each additional participant from
the same company.

Get ready for a thorough education in Slab Lifting, Soil Stabilization, the Alchemy-Spetec Deep Lift® process, equipment, and applications. You’ll get hands-on training from a technical staff with decades of on-the-job experience.

Tuesday, October 4th

• Geotech Product Line Overview
• Geotech Applications & Case Studies
• MixMaster Pro Slab Lifting Gun
• Slab Lift Rig Demonstration

Wednesday, October 5th

• Pump Demos & Training
• PolyShark® / Soil Stabilization
• Deep Lift® 
• Ground Penetrating Radar

Thursday, March 31st

• PolyBadger® Mobile Slab Lifting System
• Estimating Material for Jobs

THIS EVENT HAS BEEN CANCELLED