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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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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In the realm of grouting, patience and a methodical approach are key to achieving optimal results. This is particularly true when it comes to the concept of stage grouting, a technique that ensures effective curtain grouting with polyurethane.

The Concept of Stage Grouting

Stage grouting is not about pumping a predetermined amount of grout into a hole. Such an approach would result in the grout pushing away from the wall, which is not the desired outcome. The goal is to keep the grout close to the wall, as the purpose of this process is waterproofing, not soil modification or permeation grouting.

The Methodology of Stage Grouting

The stage grouting process begins with a cup test to determine when the grout starts to react and turn into foam. Typically 45 seconds to a minute is a good time but adjust as necessary for field conditions. At this point, it is recommended to pump a small amount of grout, perhaps a third or even a quarter of the planned total, into the hole. After that initial amount begins to react, another burst of grout is pumped in, and the process is repeated. The aim here is to slowly build a foam mass on the backside of the wall. This foam mass, once formed, will hold the new grout against the wall, allowing it to travel vertically or horizontally. This is the desired outcome, as it facilitates communication between the ports or holes drilled into the wall.

The Importance of Stage Grouting

Stage grouting is a crucial technique in curtain grouting. Many issues arise when too much material is used without significant impact. Stage grouting allows for careful monitoring and slow, methodical application, ensuring that the grout is effectively used and serves its purpose. If, after several stages of grouting, no progress is observed, it may be necessary to move to another area. This could indicate an anomaly or unidentified voids. The key takeaway here is that the right answer is never to pump more grout when in doubt. The process should be slow, methodical, and thoughtful to ensure impact.

With technical expertise and reliability, the methodical approach of stage grouting emphasizes the importance of patience and careful monitoring in achieving optimal results. Remember, when it comes to grouting, the goal is not to use more material, but to use the material more effectively. Go slow, be methodical, think about it, and make sure you're having an impact.

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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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So, you have another clog in your boot? Well, your grain elevator boot that is. This means shutting down to clean your grain elevator. Which means loss of production, loss of grain, and delays. Drains and sump pumps clog and can be unreliable. 

A grain cooperative in Washington state contacted Kodiak Concrete Lifting. Alchemy-Spetec's Leak Seal Division Director of Technical Services, Charlie "The Grout Geek" Lerman, met Kodiak on-site and inspected the leaking boots in question. One was poured concrete and the other was poured concrete with a metal interior liner. Both had multiple areas of water intrusion and sumps that were not able to handle the leakage. Charlie worked with Kodiak on developing a grouting plan and an estimate for the co-op.

Powerful Polymer

Spetec PUR HighFoamer was the ideal grout for forming a positive side waterproof barrier known as a curtain wall without having to excavate and with very little downtime.

Spetec PUR HighFoamer is a highly expansive grout (40x-50x) and it is also NSF 61-approved for potable water use.

Painless Procedure

Pumping polyurethane grouts is done with a modified airless paint sprayer. Since this pump is lightweight, it is easy to mobilize in remote or difficult-to-access locations. Normally, the technicians would set up a 2’ on-center grid pattern for curtain wall grouting. With the elevator equipment layout, they had to adjust the spacing. By pumping hole to hole they ensured water-tight grout coverage even with the irregular port spacing.

Rapid Result

A few weeks later, Charlie Lerman and Kodiak met back on-site for the installation. While working in a grain elevator pit and working with urethanes can be a bit messy, the injections went well and the water intrusions were stopped in both pits on time and under budget.

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A homeowner in Alaska reached out to contractor Ace Dragon about leaks in their basement. The basement was built with insulated concrete form walls that are typically installed in colder climates. Despite being an excellent solution, problems can arise if not installed properly during construction and the home was suffering from leaks due to poorly consolidated concrete within the walls. During construction, these specially designed walls provide insulation with concrete filling the hollow cavities. However, whenever concrete is poured it requires vibration to ensure it is properly consolidated. The walls in this home did not contain properly consolidated concrete and thus were leaking.

Powerful Polymer

After conducting a thorough inspection, the crew from Ace Dragon found issues with the membrane around the perimeter of the house and proposed injecting Alchemy-Spetec’s Spetec PUR Highfoamer into the walls to make up for the weakly consolidated concrete and seal the leaks. This durable polyurethane was perfect for this job due to its low cost and high expansion rate.

Painless Procedure

The job only required a small three-man crew and some light equipment. Starting their injection procedure from the bottom, the crew worked all the way around and up the entire basement wall to ensure all affected areas were sealed. The homeowner’s only other effective alternative would have been to excavate around the entire perimeter of the home and completely redo the membrane (something they wanted to avoid due to the high costs).

Rapid Result

The injection process took a fraction of the time a full membrane replacement would have taken. The homeowner was thrilled to have the leaks sealed and the basement walls fortified.

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In Louisville, Kentucky the Presbyterian church owned two historic buildings with an alley between them. Last century, an addition was added removing the alley and connecting the two buildings. Unfortunately, the addition was not properly waterproofed during construction. This led to water below-grade infiltration and a plethora of very complex leaking cracks and joints in the basements of both buildings and the new connecting structure.

The building is still home to a Presbyterian church. For years, the administrators have been simply dealing with the water by channeling it, as best they could, to sump pumps. Many and various repair attempts have been made over the years, but none of them have been successful in the long term. Recently, the church administration reached out to BJB Restoration for help with this ongoing issue. Due to the complexity of the project, Alchemy-Spetec's Director of Technical Services - Leak Seal Division Charlie "The Grout Geek" Lerman was called in to consult on the job.

Powerful Polymers

The technicians chose Spetec PUR HighFoamer as the repair material for this job because its expansive nature when catalyzed with Spetec GEN ACC Accelerator makes it a very cost-effective curtain grouting polyurethane resin. This one-component, closed-cell, hydrophobic, water-reactive, solvent, and phthalate-free, low-viscosity resin is also ideal for filling any voids created by the water underneath the basement slabs.

Painless Procedures

This particular job was what we like to call exploratory grouting, focused on two trial areas of complex cracking. The crew started injecting in the area of the primary leak. As they injected, water and foam began to bubble up along an adjacent and previously unidentified trench-like defect as well as the cracking being addressed. The initial injection covered the main crack and a surrounding area of about 16 feet (thanks to the expansive nature of Spetec PUR HighFoamer). Outgassing (CO2 produced during polymerization) was visible in numerous defects outside of that radius, requiring additional injections to seal the entire area.

Rapid Results

This one-day exploratory grouting project provided the contractor with a very accurate understanding of the type of problem and soil conditions they were dealing in the basements. The contractor and church administrators subsequently agreed upon a long-term maintenance plan based on the church's budget that calls for periodic curtain grouting over the next few years to address the many remaining basement floor defects in both buildings.

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Whether you think about it a lot or not, our wastewater system is crumbling and we spend billions, nationwide, each year treating groundwater that has entered our collection systems. This problem is too costly to ignore, but can be hard to address with the tight budgets many rural sewer districts are on.

On June 24, 2022, the EPA announced up to $18 million in available federal grant funding via a request for applications to provide training and technical assistance to serve small, rural, and tribal community wastewater systems. This funding will improve public health and environmental protection by helping to ensure that wastewater in these communities is safe and treated before being responsibly returned to the environment.

While the federal government is providing the grants, Alchemy-Spetec can train municipalities and their contractors on how to easily address the low-hanging fruit of water infiltration found in manholes and lift stations. Not only can we help you identify trouble areas in your collection systems but we also provide high-quality grouts coupled with the industry's top technical support.

August is just about booked out and there are only a couple of spots left for September for our manhole leak seal demonstrations. If you are unsure of how you would like to move forward, contact us to set up an online meeting to discuss your specific challenges and/or needs.

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