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There are five basic steps to be done when placing a crack injection. This is crack injection 101. Learn these steps and you will be well on your way to understanding what it takes to seal a water leak in concrete with products such as Spetec PUR F400 and Spetec GT500. In future articles, we will explore every one of these steps in more detail and address the multitude of options (such as port selection, hole spacing, depth, what to do when you hit rebar, etc.) But for right now, we are going to discuss the most basic steps.

Step 1: Drill holes. Use a hammer drill to drill holes in the concrete that intersects the crack. These holes are usually drilled at a 45-degree angle to intersect the crack halfway through the structure so that the resin is forced toward the front and back of the crack.

Step 2: Flush the holes. When you drill, you create concrete dust. If you don’t flush this dust out of the holes, it will be forced into the crack during injection and may clog the crack, preventing the resin from getting where it needs to go. Put a flexible hose all the way to the back of the hole so that water flushes the dust from the back of the hole to the surface of the concrete. Flush until clean water is flowing.

Step 3: Install your injection port. The port is what seals the hole and gives the injection pump a direct connection to the crack.

Step 4: Flush the crack. Unless the water is pouring out of the crack, you will need to inject clean water through the injection port and into the crack. This serves several purposes:

• Cleans the crack of dirt and other contaminants to allow the resin to flow freely.
• Gives you an idea of how far and how easily the resin will flow into the crack when you start injecting the foam.
• Helps to open areas where the resin wouldn’t otherwise flow. Water is thinner than resin and will penetrate deeper and into tighter areas.
• Ensures the resin will have enough moisture to react with.

Step 5: Inject the resin. Always use the lowest pressure that will continuously feed resin into the crack. Slowly turn up the pressure as necessary to get the resin flowing. My rule of thumb is to keep injecting even if resin starts to flow out of the crack. As long as more resin is going in than is coming out, you are improving your chances of success. When the resin isn’t moving further along the crack, move to the next port.

Sounds simple, right? Well, it is and it isn’t, as we will discover in the next several chapters of this blog series...

5 Steps of Crack Injection - Overview
5 Steps of Crack Injection - 1. Drilling Holes
5 Steps of Crack Injection – 1. Drilling Holes (Continued)
5 Steps of Crack Injection – 2. Flushing Holes
5 Steps of Crack Injection – 3. Installing Ports
5 Steps of Crack Injection – 4. Flushing Cracks
5 Steps of Crack Injection – 5. Injecting Resin

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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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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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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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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.

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