Alchatek Blog

I remember my first day on the job back in June of 1985. We were working nights in the subway tunnels of Atlanta, sealing leaks in the ceiling. The crew handed me a 30-pound hammer drill and told me to drill holes in the ceiling at a 45-degree angle. Sure, what the heck is a 45-degree angle? I put on a lot of muscle that summer drilling overhead and hauling 50-pound pails of resin all over the Southeastern U.S.

Drilling holes into concrete seems like a straightforward process. However, it must be done correctly or everything you do afterward is a waste of time. Often, contractors put their least experienced technician on that job because it is manual labor and can be taught quickly. But knowing a few of the basics can help a newbie drill like an expert.

First, you have to understand that the beginning of the hole is where the injection port makes its seal against up to 3,000 pounds per square inch of injection pressure. It is important that the hole stay round, especially when using hammer in type ports. That means you have to keep the drill bit in a straight line.

Why a 45-degree angle? This is the best way to intersect the crack halfway through the structure (which is your goal). For example: On a 10” thick wall, come off the crack 5”, drill at a 45-degree angle and you should hit your target. Just start with your drill bit straight into the wall, give the trigger a few bumps to make an indention in the concrete with the bit, and rotate your drill so that the angle is halfway between your starting position and the wall.

How far apart should you space your holes? It depends on the width of the crack. Tighter cracks need tighter spacing because the resin won’t travel as far. Wider cracks can have wider spacing because the resin will travel with ease. A rule of thumb is to drill your holes no farther apart than the thickness of the concrete. Drill, flush, and pump a test hole with water to get an idea of how far the resin will travel.

Be sure to pull the drill bit out every four or five inches of penetration to clean out the drilling dust. Otherwise, you are likely to bind up your drill bit, which is not fun to try to remove.

Sometimes you will have to drill straight into the crack. I always try to angle drill first, but with extremely tight cracks you may have to compromise and drill straight in. Go as deep as you can, but make sure you don’t go all the way through.

Another tip: If you stagger your holes from one side of the crack to another, be sure not to intersect a hole you already drilled. This causes all kinds of problems.

We will talk about flushing drilling dust out of your holes later, but I can’t repeat it enough. If you want a successful injection job you have to flush the drilling dust out of the holes from the back. Otherwise, the dust will form a paste that gets forced into the crack and blocks your resin from getting where it needs to be. Splashing water on the front of the hole doesn’t really help. Be sure to get a small hose to the back of the hole and flush it with clean water.

In the next article, we'll take a look at what to do when you inevitably hit the injection contractor's nemesis...rebar!

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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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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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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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.

Want more information on leak seal products and equipment?

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.

Want more information on leak seal grouting materials and equipment?

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.

Want more information on leak seal products and equipment?

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.

Want more information on leak seal products and equipment?

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.

Want more info on polyurethane leak seal grout and equipment?

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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