Polyurethane grouting is an essential process in construction and infrastructure projects with the need to lift structures, fill voids, and stabilize soil. While polyurethane grouting has been utilized for decades, advancements in technology and technique have enabled a new level of precision and control in modern grouting applications. Innovations in polyurethane injection methods and equipment allow design and construction teams to achieve highly accurate, consistent injections for maximum strength and longevity. 

Precision is critical in polyurethane grouting applications. Inadequate filling of voids or inconsistent distribution of grout can lead to structural instability, settlement, and even collapse. Precise injections ensure that soil is saturated, voids are filled, and slabs are leveled accurately. This provides uniform load distribution and protection against shifting, vibration, and erosion. Precision also prevents wasted materials and rework due to incorrect amounts or placement of grout. 

Modern polyurethane grouting equipment and techniques enable accurate monitoring and adjustment of grout injection rates, depths, pressures, and consistency. Some examples of modern technology include: 

• Hydraulic and Electric Pumps: Modern polyurethane injection equipment includes hydraulic or electric pumps. These pumps provide precise control over pressure and flow, ensuring a more uniform injection of grout material.
• High-Pressure Injection: Modern equipment can handle high-pressure injection, making it suitable for stabilizing deep structures and addressing challenging soil conditions. High-pressure injection ensures better penetration of the polyurethane grout.
• Remote Monitoring and Data Logging: Advanced systems come with remote monitoring and data logging capabilities when necessary. Operators can monitor the injection process remotely and collect data on pressure, flow, and other parameters for quality control and documentation.
• Compact and Portable Systems: Some advanced injection grouting systems are designed to be compact and portable, making them easier to transport to job sites and set up quickly.
• Safety Features: Modern equipment includes safety features such as shut-off valves and pressure relief mechanisms to protect both operators and the equipment itself.

Modern polyurethane grouting equipment has revolutionized construction and infrastructure project challenges, offering engineers and design teams an array of precision-driven advantages. The evolution of polyurethane injection equipment, including hydraulic pumps, pneumatic pumps, and computerized control systems has empowered design teams and application technicians to achieve precise outcomes.

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The approach and departure slabs adjacent to a bridge in McKenzie County, North Dakota had settled, leading to an uneven and hazardous road surface. A geotechnical contractor was brought in to level the road surface and mitigate any further settlement. 

Powerful Polymer

The contractor selected AP Lift 475, a two-component, hydrophobic, structural lifting polymer designed for airport, highway, and railroad applications. It can be used to stabilize structures, fill voids, and lift slabs supporting tremendous loads. In addition to tremendous in situ load-bearing capacity, AP Lift 475 is also traffic-ready in less than one hour.

Painless Procedure

AP Lift 475 was injected through the approach and departure slabs to fill subterranean voids, compact the existing subgrade, and lift the settled structures. As the material was injected, the material rapidly expanded, compacting the subgrade soils. Once the subgrade was compacted and the load-bearing capacity of the soil improved, the material raised the settled slabs.

Rapid Result

The approach and departure slabs were lifted to their proper elevation and the underlying soil was improved to mitigate future settlement. This work was performed in two days. 

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The terms hydrophobic and hydrophilic may not mean anything to the average person. But, to a contractor, these terms can mean a world of difference. Hydro means water while phobic means “to fear” and philic means “to love”. Alchatek offers both hydrophobic and hydrophilic polyurethanes, so it is important to be aware of the differences between the two types.  

Hydrophobic Polyurethanes

Hydrophobic polyurethanes naturally repel water (similar to the way oil would repel water and stay separate if you were trying to mix them in a glass). These products push water out of the area in question as they expand. Hydrophobics are used with catalysts which allow you to adjust the set time. They also have zero shrinkage after curing.

Check out these hydrophobic polyurethanes:

• Spetec PUR HighFoamer 
• Spetec PUR F400
• Spetec PUR H100 
• Spetec PUR H200 
• AP Fill 420
• AP Deep Lift® 420
• AP Lift 430
• AP Lift 435
• AP Lift 440
• AP Lift 475
• AP Soil 600 
• AP Fill 700
  
• AP Fill 720

Hydrophilic Polyurethanes

Hydrophilic polyurethanes naturally mix with water before curing (similar to the way gin and tonic mix thoroughly in a glass). This characteristic allows for a very strong chemical and mechanical bond, as water helps pull the material into the pores of the concrete. These products do not require a catalyst. You can pump them straight out of the pail.

Check out these hydrophilic polyurethanes:

• Spetec PUR GT350
• Spetec PUR GT380
• Spetec PUR GT500

Don't Oversimplify These Concepts

Don't get caught in the trap of oversimplifying hydrophilic vs. hydrophobic.  There are varying degrees of each (see chart below for more information on how this is measured).  

Some hydrophilic materials will keep absorbing water (10-15 times their original volume).  Others (such as Spetec PUR GT500) only absorb as much water as is necessary for their reaction and then they reject the rest.  Yes, hydrophilic gels will shrink like crazy in the absence of water, but Spetec PUR GT500 won't.  It is completely safe to use in a dry environment.

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Raising Concrete with Confidence

When pumping a lightweight material beneath a slab, you need the confidence that it is strong enough for the application. How strong is strong enough? This is a commonly asked question by contractors that are new to slab jacking with polyurethane. Alchemy-Spetec structural foams only need to be as strong as dirt, but they're actually stronger than crystalline bedrock.

The Right Strengths for Concrete Lifting

Slab lifting foams are rated on density (weight per cubic feet) and compressive strength. This testing and rating are based on the foam in a free-rise state; the parts A and B are mixed together and allowed to expand freely. Our AP Lift 430 and AP Lift 475 structural lifting foams, for example, weigh 2.75 – 3.25 lbs (AP Lift 430) to 4.75 – 5 lbs (AP Lift 475) per cubic foot. But they have compressive strengths of 50 psi and 100 psi in a free-rise state. That's the equivalent of 7,200 to 14,000 lbs per square ft of support, just in a free-rise state.

Polyurethane Slab Jacking Compared to Clay and Bedrock

To put that into perspective, the National Home Builders Association and the International Building Code list stiff clay at 4,000 psf and crystalline bedrock as having 12,000 psf of load-bearing capacity. Consider the job site conditions where the foam will be injected into a confined area. Testing data in the lab shows that our lifting foams will increase in compressive strength: In a space confined 25% by volume there will be an increase of 31% in psi and in a space confined by 75% there will be a 79% increase in the psi.

Concrete Leveling for Any Job with the Right Foam

Today polyurethane lifting foams are used to level airport slabs supporting jumbo jets, equipment and building slabs supporting tremendous loads, and even railway sleepers that support the heaviest freight trains. So don't let the word “foam” fool you. These resins cure to strengths beyond what is needed to support any structure.

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The Alchatek app includes a Leak Seal Material Selection Guide and a 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 Geotech and Leak Seal jobs. Here's a step-by-step guide...

Install the Alchatek App and Create an Account

1. Search the name Alchatek in your Apple App Store or Google Play Store to install the app. 

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

Polyurethane Estimating Calculator (Estimate Material Quantities for Your 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) or Leak Seal for your job type.

2. Select the measuring system you want to use.

3. Fill out the required fields.

4. View the recommended material quantities.

Leak Seal Material Selection Guide (Choose 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).

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Alchatek's AP Lift foams are specialized materials utilized in a variety of construction and repair tasks. These foams have a unique characteristic where their expansion and strength are inversely proportional. This means that as the expansion of these foams increases, their compressive strength decreases, and the opposite is also true. This unique property allows Alchatek's comprehensive selection of foams to be used for a wide variety of applications, from filling expansive voids, to compressing soil, and commercial slab lifting.

Expansion & Strength

The key to understanding AP Lift foams lies in their expansion-strength relationship. AP Fill 420/Deep Lift 420, for example, has the highest expansion, making it the most economical product for filling a void. However, it also has the lowest compressive strength. On the other hand, AP Lift 475 expands less than half the amount of AP Lift 420, but its compressive strength is 370% stronger.

It's important to note that these expansion rates and compressive strengths are based on free rise foam. Free rise refers to the condition in which the material is allowed to expand with no resistance - for example, foam that was mixed and expanded in an open cup. In most practical applications, these products are injected into the soil or into a void that is closed off on most sides. The foam meets resistance as it expands, which reduces the amount of expansion and therefore increases the compressive strength. The degree to which expansion is reduced varies from job to job and is influenced by factors like soil conditions, void size and shape, and the quantity of material injected.

Product Application Guide

While each product can be used in multiple applications, here is a quick guide to product selection:

• AP Fill 420/AP Deep Lift 420: Ideal for filling large voids and for use in the Deep Lock® process. It provides an expansion of 4.25 ft³ / gal and compressive strength of 4032 psf. It has an approximate weight of 2 lbs / ft³

• AP Lift 430: Recommended for residential slab lift applications. It expands at 3.20 ft³ / gal and has a compressive strength of 7200 psf. Its approximate weight is 3 lbs / ft³.

• AP Lift 435: Perfect for warehouse slab lift applications. It provides an expansion of 2.80 ft³ / gal and a compressive strength of 9216 psf. It weighs around 3.5 lbs / ft³.

• AP Lift 440: Used for highway concrete slab lift applications. It expands at 2.40 ft³ / gal and has a compressive strength of 11520 psf. It has an approximate weight of 4 lbs / ft³.

• AP Lift 475: Suitable for heavy-duty slab lift applications. It offers an expansion of 2.00 ft³ / gal and a compressive strength of 14000 psf. It weighs approximately 4.75 lbs / ft³.

All these products are designed to work in wet environments, making them versatile for various conditions.

Additional Resources

For help calculating product quantities, you can search the word "Alchatek" on Google Play or the Apple App Store and download the Alchatek material estimating app. This tool can assist you in determining the right amount of AP Lift foam needed for your specific project.

Understanding the properties and applications of AP Lift foams can significantly increase the margin and reduce the costs of your construction or repair projects. By leveraging the unique expansion-strength relationship of these materials, you can select the right product for your specific needs, whether it's filling large voids, lifting driveways, or handling commercial slab lifting applications. With the help of our experienced team and tools like the Alchatek estimating app, you can calculate the required quantities, making your work easier, simpler, and more profitable.

The key to successful application lies in understanding the conditions of your project and choosing the right AP Lift foam product accordingly. Whether you're dealing with wet environments or specific soil conditions, there's an AP Lift foam designed to meet your needs.

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Alchatek offers a series of short educational videos covering a variety of polyurethane concrete repair applications. Each video is described below, followed by a viewing link.

Slab Lifting with Polyurethane Foam

This live-action video depicts a typical residential driveway slab lifting job, including a simple overview of the causes of settled slabs, the alternatives to polyurethane slab lifting, and the polyurethane slab lifting process itself. The slab lifting sequence features added 3D animation to show the foam expansion process underground during the slab lifting process. Click here to watch the video.

The Polyurethane Slab Lift Process Explained

This animated video explains the polyurethane slab lift process in detail, primarily in the context of commercial/industrial applications. Sunken concrete slabs can be lifted back into place with two-component polymer foam designed to work in wet or dry conditions. The expansion force of the concrete leveling foam coupled with the pressure of a specialized pump generate enough controlled force to lift virtually any structure back into position with 1/8” precision.  Click here to watch the video.

The Polyurethane Soil Stabilization Process Explained

This animated video explains the most common infrastructure and concrete issues requiring polyurethane soil stabilization, as well as the application process itself. Unstable, eroded, or loose soil around infrastructure can result in settlement and damage to the structure. Voids can be filled, soil consolidated, and water migration halted by permeating the soil with one of the AP Soil series of polyurethane resins. Click here to watch the video.

The Deep Lock® Process Explained

This animated video explains deep soil stabilization in great detail. Alchatek offers a unique combination of high-quality structural polymers along with the equipment and training needed to address deep soil issues. Contractors trained in The Deep Lock® process can stabilize soil at all levels and accomplish this with minimal imposition to or downtime for the property owner. Click here to watch the video.

The Polyurethane Leak Seal Process Explained

This animated video explains the most common infrastructure and concrete issues requiring polyurethane leak seal solutions, as well as the various application processes. Leaking concrete can be detrimental to safety and property values. Leaks in concrete structures can be permanently repaired with water-activated polyurethane and a few assorted leak seal accessories. Click here to watch the video.

Alchatek - A Supplier You Can Trust

This video provides a quick overview of Alchatek, an international leader in the manufacture and supply of chemical grouts and construction products for Geotechnical, Leak Seal, and Seawall Repair applications. Providing solutions from its headquarters in Tucker, Georgia, and its manufacturing facility in Reno, Nevada, Alchatek specializes in advanced construction technologies for sealing leaks, stabilizing soils, lifting concrete, and protecting infrastructure and seawall structures. Click here to watch the video.

Want more information on geotech and leak seal products and equipment?

Alchatek offers world-class custom-built pump systems for both slab lifting and soil stabilization applications. If you're looking for a full-sized trailer rig system, click here to read more on that subject. In this blog post, we'll take a look at two propriety systems designed by the professionals at Alchatek. 

The PolyBadger: Compact Lifting System on Wheels

The wheel-mounted PolyBadger two-component pump system is an extremely valuable addition to any slab lifter's arsenal. It is perfect for new contractors looking to make an initial investment and for experienced contractors looking to add a portable option for those hard-to-reach locations. Small enough to fit in the back of a pickup truck, this simple system requires minimal equipment.

• Lower Initial Investment
• Less Equipment Needed
• Easily Fitted to a Truck, Trailer, or Cart

The PolyShark: Skid-Mounted Soil Stabilization System

The skid-mounted PolyShark single-component pump system is essential for large-scale soil stabilization and void-fill projects. The PolyShark system includes a gas-powered high-pressure injection pump, two hose reels, and flow meters. The entire skid-mounted system can easily be fitted to a flatbed truck for efficient transport.

• Ideal for Large-Scale Jobs
• Complete System (Pump, Hose Reels, Flow Meters)
• Easily Fitted to Flatbed Truck

Want more info on Alchatek geotech products and equipment?

Slab Lifting Overview

Over time, concrete surfaces settle and need to be lifted and leveled. Polyurethane foam is an effective slab lifting method. The process involves injecting polyurethane into voids beneath the concrete surface to lift and level the slab. Cost-efficient and effective, this method has become increasingly popular over time.

Slab lifting with polyurethane is non-invasive, quick, and causes minimal disruption to nearby areas. Small holes are drilled into the concrete and foam is injected through them. The foam expands, filling voids beneath the slab and lifting it back to its original position. 

Slab Lifting Products

AP Fill 420

AP Deep Lift® 420

AP Lift 428

AP Lift 430

AP Lift 435

AP Lift 440

AP Lift 475

Every member of Alchemy-Spetec's industry-leading technical support team is thoroughly versed in the art and science of slab lifting with polyurethane. Contact us today at 404-618-0438 for assistance with your next slab lifting project.

Want more information on slab lifting with polyurethane?

Alchemy-Spetec HQ in Tucker, GA

Registration Deadline - April 15th

May 2nd - May 4th
$745 Registration Fee
$665 for each additional participant from
the same company.

Get ready for a thorough education in Slab Lifting, Soil Stabilization, the Deep Lock® process, Crack Injection, and Curtain Grouting. You’ll get hands-on training from a technical staff with decades of on-the-job experience.

Agenda Items

• Geotech Product Line Overview
• Geotech Applications & Case Studies
• MixMaster Pro Slab Lifting Gun
• Slab Lift Rig Demonstration
• Pump Demos & Training
• PolyShark® / Soil Stabilization
• Deep Lock® 
• Ground Penetrating Radar
• PolyBadger® Mobile Slab Lifting System
• Crack Injection
• Curtain Grouting
• Estimating Material for Jobs