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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Alchatek'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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Today, we delve into the technicalities of hydraulic cement and crystalline cement versus polyurethane grout for leak seal injection. This article aims to provide you with detailed, actionable information to guide your decision-making process.

Understanding Your Options

Hydraulic cement, crystalline cement, and polyurethane grout are not competing product categories. Instead, they each offer unique benefits and applications. Hydraulic cement and crystalline cement are cost-effective and easy to apply, making them a go-to solution for many common situations. They share similar properties with basic cement repair, providing a reliable solution for static structures.

However, let’s be clear. If your crack or joint is subject to any significant movement, hydraulic and crystalline cement may fail over time, just like common cement. Yes, crystalline cement does expand over time and fill cracks, but it’s not designed to handle excessive movement. (This fact is actually listed on crystalline cement manufacturer technical data sheets.)

When to Use Polyurethane Grout

Polyurethane grout is the appropriate choice when a structure is subject to movement over time. It’s a more complex and costly solution (in the short term) than simply using hydraulic cement, but worth the investment in the long term.

Consider a three-foot thick potable water tank filled with rebar. You might have a hairline crack - a minor weeper - held together by the rebar. You could easily seal this with hydraulic or crystalline cement, and the leak would stop for the short term. But remember, you still have three feet of water in your concrete, and your rebar is potentially exposed to that.

In such a case, full-depth injection using a polyurethane grout would be highly beneficial. This product has characteristics that hydraulic cement doesn’t have, making it a more reliable solution for dynamic structures.

The Issue of Movement

Movement is the biggest challenge when using hydraulic cement. In manholes, for instance, you’ll often see pipe invert laterals coated with hydraulic cement to stop leaks. But the leaks return year after year, requiring more and more cement.

Why not choose a more lasting solution? Use a urethane once, spend a little more, and have a flexible product in place. You won’t ever have to do it again. It’s simple, and it’s long-lasting.

Final Thoughts

Let’s address a common scenario. Parking garages often operate on tight budgets. When faced with the cost of injecting all the cracks, the owner may not have the entire budget at the moment - but still need to stop the leaks. In such cases, we recommend starting with hydraulic cement or crystalline cement to stop the leak on a short-term basis - but also start saving/budgeting for a permanent polyurethane crack injection solution.

Remember, leaks may return due to structural movement caused by thermal cycles or expansive soil swelling. When they do, you’ll need to address them. By providing a quick solution now and helping plan for the future, we build trust with our clients. Many buildings and parking garages set up remedial grouting programs to address long-term problems periodically.

Contact us for more information on the best grouting solutions for your specific needs. We are committed to providing you with reliable, professional, and detailed information to guide your decisions. Remember, the choice of materials is paramount, and we are here to help you make the best choice.

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Restoration waterproofing is always a unique undertaking as there are many unknowns. Identifying the source of the infiltration is the obvious first step and it is a challenging one. Properly diagnosing a leak may require numerous steps that include, but are not limited to, inspection, flood testing, dye testing, mock-ups, removal of finishes, and occasionally destructive test methods.

Setting Clear Goals

Before embarking on a restoration waterproofing project, it is important to set clear goals and expectations for all parties involved. Clearly, stopping water intrusion is normally the main goal. Various methodologies and products can be employed to achieve this goal. Each of those may have different costs, varying levels of site disruption, and varying timetables. These should all be discussed so the end customer can make a well-educated decision.

Understanding Water Migration

It is important to understand a few key concepts about water migration. Just because a leak only manifests in specific areas does not mean that there are no other locations allowing water ingress. Water seeks the path of least resistance, typically the low spots. As these low spots are remediated, the water may migrate to other failed areas. This can be further complicated if the repairs are conducted during a relatively dry time, as the leak migration may not manifest until the next rain event. Conducting waterproofing repairs during active leaking helps to identify leak migration issues. Flood testing before, during, and/or after the work also can help identify leak migration.

In summation, remedial waterproofing is often an explorative process and can require on-the-fly adjustments. Setting expectations, maintaining open communication with all involved parties, and attention to detail are essential to making the waterproofing process efficient and successful.

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Are you in search of a reliable material supplier for polyurethane leak seal and geotech applications? Look no further. Alchatek, an industry leader in the manufacture and supply of chemical grouts and construction products, is the partner you need. Alchatek is a name synonymous with trust and reliability.

Advanced Construction Technologies

Alchatek specializes in advanced construction technologies for sealing leaks, stabilizing soils, lifting concrete, and repairing seawalls. Alchatek is organized into three divisions:

• The Leak Seal Division features polyurethane crack injection and curtain grouting solutions.
• The Geotechnical Division features concrete leveling, soil stabilization, and Deep Lock® deep stabilization solutions. 
• Seawall Repair Network® is the only national, all-inclusive seawall repair and preservation network.

A Supplier You Can Trust

Alchatek offers the most experienced technical support team in the industry, backed by extensive product expertise and decades of on-the-job training. This dedication ensures that you can build your business and complete your most important jobs with confidence. In addition, our commitment to manufacturing the highest quality products in the USA ensures that you receive the most reliable materials on the market.

So, are you ready to start your business or take your projects to the next level with a supplier you can trust? Call 404-618-0438 today to get started.

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As a geotechnical engineer, you understand the importance of stable supporting soil around structures. When the supporting soil becomes unstable, the stability of the structure is at risk. Common causes of unstable soil include erosion, poor compaction, freeze/thaw cycles, and decomposition of organic materials within the soil. Fortunately, soil can be stabilized with high-strength polyurethane. Whether you need a product recommendation for soil stabilization specs, or you're seeking accredited continuing education on this subject, Alchatek has you covered.

Product Recommendations for Soil Stabilization Specs

Experienced members of the Alchatek technical support team consult with engineers on a regular basis. When you call for assistance, you'll be connected to someone with extensive product knowledge and years of on-the-job experience out in the field. If you need a product recommendation for polyurethane soil stabilization specifications, call 404-618-0438 and ask for a geotechnical expert. 

Accredited Presentations

Alchatek offers one-hour CE/PDH accredited presentations on a variety of subjects, including geotechnical applications for polyurethane. These presentations are available online via videoconferencing or in person in a lunch-and-learn context. Geotechnical presentations are always given by an experienced expert who can field pretty much any question your team may have on the subject.

Click the button below and fill out the form to request an accredited presentation.