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 concrete 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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If you're a leak seal contractor, you may be familiar with this situation: A property owner with leaking concrete calls you up and says, "Hey, everything is dry right now, so I want to get someone out here to go ahead and waterproof the structure."  Attempting a waterproofing job when the structure is completely dry is not recommended.

Let me give you an analogy. Let's say I hired you to paint a basement. And when you arrive, it's pitch black in that basement. No lights are available and you can't see anything. Can you still paint that basement? The answer is "yes", but when we turn the lights on, will I be happy with the job you've done? There's no way. It would be a terrible paint job.

Similarly, if someone is asking you to waterproof while it's dry, you are basically attempting to seal leaks while blind. You need to waterproof while water is present - not just to activate the grout, but to see where the grout needs to be. Let the leaks lead you to correct grout placement. You won't know for sure if the water is not present. If you attempt a leak seal job in a completely dry environment and then return when the water is present, you'll most likely find leaking cracks that you missed.

Moral of the story? Grout when it's wet.

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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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Polyurethane grouting is a complex process that involves numerous specifications and guidelines. However, amidst the vast amount of information, there are five fundamental rules that lie at the core of all successful polyurethane grouting projects. We will explore these rules, highlighting their significance in achieving desired outcomes.

Rule #1: Don’t Eat the Grout

On a serious note, this rule serves as a safety reminder to avoid accidents or potential health risks associated with ingesting grout materials. It may seem obvious, but it is crucial to emphasize that grout should never be ingested.

Rule #2: Protect Your Eyes

Ensuring eye protection is essential when working with polyurethane grout. Always wear appropriate safety gear and keep an eyewash nearby. This precautionary measure prevents grout particles or splashed drops from coming into contact with your eyes, safeguarding your vision and preventing injuries.

Rule #3: Avoid Premature Water Addition

One must refrain from adding water to the grout before pumping it. While experienced professionals might occasionally deviate from this rule, it generally stands as a reliable guideline, especially for those new to the field. By adhering to this rule, the grout maintains its intended consistency and properties, leading to optimal results.

Rule #4: Get the Grout in Right Location

Precise grout placement plays a crucial role in achieving successful outcomes. It is essential to accurately direct the grout to the desired location whether performing crack injections or high-flow grouting. High-flow grouting, especially, demands effective retention of the grout in place.

Rule #5: Allow Sufficient Set Time

The final rule stresses the importance of providing ample time for the grout to set. Once the grout reaches its intended location, it is crucial to avoid disturbances and allow the curing process to occur effectively. This rule is particularly significant in high-flow scenarios, where maintaining the grout in place poses a significant challenge.

As long as these rules are upheld, exploration and experimentation in grouting methods can be undertaken. This approach acknowledges the uniqueness of each job site and encourages problem-solving while adhering to the core principles of grouting.

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It’s crucial to determine if your project requires products that meet NSF/ANSI 61-5 standards for contact with drinking water. But what exactly are NSF/ANSI/CAN 61 standards? Our goal here is to provide a concise and comprehensive overview of why NSF approval is important for polyurethane geotech and leak seal materials.

What is the NSF (National Sanitation Foundation)?

The National Sanitation Foundation develops public health standards and certification programs that help protect the world’s food, water, consumer products, and environment. Their organization ensures that adequate testing is conducted for all products that will be used in or around drinking water from source to tap.

An NSF compliance brief reads: “NSF, an independent, private, not-for-profit, third-party certification organization founded in 1944, has developed numerous health-based certification programs and consensus standards including those that relate to drinking water…The purpose of its certification program is to promote public health and enrich the quality of life. Through its Council of Public Health and Health Advisory Board, which includes EPA health professionals, it obtains guidance in developing and maintaining programs and standards. NSF also partners with code councils to ensure ongoing compliance.”

Each product must undergo rigorous testing to receive NSF approval. The manufacturer's plant and quality assurance practices must pass a thorough inspection. Voluntarily undergoing such a rigorous certification process is invaluable to all parties involved.

The SDWA (Safe Water Drinking Act)

The Safe Water Drinking Act (SDWA) gives the EPA latitude to impose criminal and civil penalties on industries that are not in compliance. In 2014 enforcement efforts policing clean water netted $163 million in penalties and fines, 155 combined years of incarceration for sentenced defendants, and $16 million in court-ordered project clean-ups.

Because so many of those defined contaminants are pertinent to even the most basic construction projects – turbidity from soil runoff, leaching from PVC pipes, potentially harmful and corrosive chemicals, and more – understanding and adhering to the law is particularly important for industry stakeholders. Contractors and engineers must be able to confidently choose vendors whose products and services won’t become the source or cause of drinking water contamination either in the short or long term. Having products that may come into contact with drinking water certified to NSF/ANSI/CAN 61 (approved for contact with drinking water), ensures compliance with the SDWA.

Alchatek NSF Approved Products and Solutions

Alchatek's NSF-certified materials are evaluated and lab-tested, and the production facilities are inspected and annually audited for re-testing to maintain certification. 

The following products have received the official NSF seal of approval for contact with drinking water:

• AP Lift 430
• AP Lift 475
• AP Soil 600
• AP Fill 700
• AP Fill 720
• Spetec PUR F400
• Spetec PUR GT500
• Spetec PUR HighFoamer
• Spetec PUR H100
• Spetec PUR H200
• Spetec AG200

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In this article, we’re comparing the use of epoxies and polyurethanes for waterproofing. This is not a battle of good versus evil, but rather a discussion about their differences and when to use each type of material.

A Brief History

Epoxies and polyurethanes are both old technologies, with epoxies making their way into the construction market about a decade before polyurethanes. The term “chemical grouting” often refers to epoxy, much like how “soda” is used as a generic term for carbonated drinks.

Why Epoxy?

When you’re asked to waterproof with epoxy, it’s essential to ask why. Are you merely waterproofing, or are you also doing a structural repair? Epoxies are strong, about three to four times stronger than the concrete you put them in. They will waterproof that crack, but when movement occurs, you’ll likely see mirror cracking about a foot over on either side. When you have mirror cracking, your water problem will return.

The Case for Polyurethane

If you’re just looking to waterproof, polyurethane is almost always going to be the better choice. Polyurethanes are flexible, allowing the wall to move and breathe as it needs to while stopping the water from coming in. It’s simple that way.

Wet Environments and Polyurethanes

One other point worth noting is that polyurethanes can be installed in wet environments. That’s typically when you have the leak. Epoxies, on the other hand, don’t like to be installed in wet situations. Remember, it’s not about which one is better overall, but about which one is better for your specific situation. As always, feel free to contact us with any questions about epoxy vs polyurethane for waterproofing or for assistance with your waterproofing project.

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“At what pressure am I going to inject the grout?” This question is not only common but also crucial on leak seal jobs, as it directly impacts the quality of your work. The answer, however, is not as straightforward as one might hope. The optimal pressure for injection is as low as possible. However, the exact pressure cannot be determined until the injection process begins.

Hairline Cracks

When dealing with urethane and hairline cracks, the pressure required is generally on the high end. This is where the technical expertise comes into play. If the pressure is too high, there is a risk of spalling the concrete, which can lead to further damage. To mitigate this risk, one might consider switching to an acrylate-type product. Acrylate, being almost as thin as water, penetrates hairline cracks more effectively, thereby reducing the risk of spalling.

Process of Injection

As a rule of thumb, the process begins by connecting to the port, whether for crack injection or curtain grouting. The ball valve is opened while the pump is off. Once the pump is turned on, the pressure is gradually increased until a steady flow rate is achieved. This process requires a keen eye and a steady hand, reinforcing the importance of technical expertise in this field.

The Concept of Exploratory Grouting

The in world of crack injection, there is a concept known as exploratory grouting. This process involves intentionally creating one small crack to understand the wall’s resistance. Typically, walls start cracking around 1500 PSI, although this can vary, with some walls withstanding up to 2200 PSI. This exploratory process is essential for understanding the wall’s capacity and planning the injection process accordingly.

Marking the Pressure

It is recommended to mark the pressure at which the wall cracks using a wax pencil on the pump. This marking serves as a reminder of the wall’s capacity. Remember, you get one free crack for exploratory purposes. Any cracks after that are on you. 

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A question that often comes up in our line of work is whether a cartridge can be used to inject cracks, specifically leaking cracks in concrete. The answer is a resounding yes...depending on the situation. In some cases, an electric injection pump is ideal, and in others, a cartridge is the way to go.

When to Use an Electric Injection Pump

An electric injection pump provides constant pressure and a steady flow making it ideal for treating most concrete cracks. Cartridges and hand pumps on the other hand create uneven pressure with each stroke and are often less effective on tight cracks. And a second pump for your water can be a game changer. Remember, the choice of tools is paramount in this line of work. 

When to Use a Cartridge

So why bother with a cartridge if it is less effective on tight cracks? Often residential basements have wider cracks. On these types of small jobs, not having to mobilize and then clean up a pump can be more efficient. In precast manholes, cartridges are often used on precast joints for the same reasons. Like most things, there is no one fix-all for every situation.

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An Oakwood, Georgia corrugated metal pipe rehab job, involving the replacement of the end caps, resulted in soil migration through the new joints. This in turn led to depressions in the asphalt road above. The City of Oakwood public works department called in Atlanta-based geotech specialists LiftitRite to assess and repair the pipe and the soil.

Powerful Polymer

Alchatek's AP Fill 700 was an easy choice for this project. AP Fill 700 is a single-component, water-activated, hydrophobic polyurethane resin that is highly effective in cutting off high-flow underground leaks, filling voids, and stabilizing soil. It is also NSF/ANSI/CAN 61 approved for contact with drinking water.

Painless Procedure

The technicians began by stuffing the larger joints with resin-soaked Oakum to create an impermeable gasket. Then, injection ports were installed adjacent to the joint in a clock pattern. The crew injected AP Fill 700 until the joints were fully sealed and permeation of the surrounding soils was achieved.

Wanting to ensure a “belt and suspenders” repair was done, they opted to inject AP Fill 700 through the top of the road as well via injection probes. The probes were driven down to depths coinciding with the tops and sides of the culvert pipes. These injections ensured that all voids and shifted soils caused by the pipe infiltration were filled, permeated, and stabilized - thus preventing any future road depressions or dropouts.

Rapid Result

City of Oakwood officials were extremely pleased to see this issue remedied in just 2 days via an effective and affordable solution that involved minimal traffic disruption and zero excavation. 

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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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