Alchatek Blog

All cracks that aren’t actively leaking at the time you are sealing them need to be flushed out with water. Flushing them gives you several advantages:

1. Let’s you know whether your drill holes have intersected the crack.
2. Flushes dirt and debris out the surface of the crack so your resin has a cleaner internal surface to bond to.
3. Reveals how far you can expect the resin to travel so you know if your drilled holes are close enough together.
4. The water will help open up tight cracks that the thicker resin may not otherwise have been able to penetrate.
5. Ensures that the resin has sufficient moisture to react with.

Start at the lowest point in the crack and flush clean water through your injection ports. It is best to have at least two pumps onsite. One for pumping water and one for pumping resin. Use the same type of high pressure pump that you use for resin. You can use a smaller pump if you like, as long as it is capable of generating between 2,800 and 3,500 p.s.i.

BE CAREFUL when flushing tight cracks! The low viscosity of water coupled with the high pressure of the pump can shear the concrete. The water can push into tight cracks and capillaries and all at once split your concrete. You can also shear concrete with resin, but it is more likely to happen with water because you are testing your crack and trying to open it up.

Always start every port with the lowest pump pressure and slowly turn it up as necessary. Also, slowly crack the valve open when you are first injecting water or resin. This is a critical moment in the process. If you forget to turn the pump pressure down after each port, you risk blasting high pressure into the port all at once which can result in shearing of the concrete or blowing out the port.

Keep injecting water as long as it is flowing through the port and moving further and further along the crack. Monitor the water coming out of the crack. Notice if it is clean or cloudy. Keep injecting until it comes out clean.

If the project is big enough, you can have one technician injecting water and another injecting resin right behind. Personally, I like to do both steps myself. That way I know what to expect when injecting the resin. In any case, keep the water pump nearby. Many times you will have to pop another hole in the wall here and there to completely seal the crack with resin.

Click below to read the previous articles in this series if you missed them:
5 Steps of Concrete Crack Injection - Overview
5 Steps of Concrete Crack Injection - 1. Drilling Holes
5 Steps of Concrete Crack Injection – 1. Drilling Holes (Continued)
5 Steps of Concrete Crack Injection – 2. Flushing the Holes
5 Steps of Concrete Crack Injection – 3. Installing the Ports

Click below to read next articles in this series:
5 Steps of Concrete Crack Injection – 5. Injecting the Resin

Want in-depth info on crack injection procedures and products?

Installing high pressure injection ports is pretty straight forward, so I won’t spend too much time on this topic. Just a few quick tips.

1. Hammer In Ports. Place the port in a clean 3/8” diameter hole and hammer it in. The high quality materials our ports are made of will take a pounding. But you don’t have to hammer them in too hard. With a little practice you will begin to notice the sound changes slightly when the port is seated. Use an electric screwdriver or drill with a 5/16” socket to seat the zerk fitting into the port. Also, make sure you have a “T” handle socket for use in areas where water is pouring down on your head (so you don’t short out your electric screwdriver or drill).

You may notice that the bag of ports is wet on the inside when you get them. The water helps the ports stay resistant to cracking.

The downside to Hammer In Ports is that they only contact the concrete in a very small area and make a seal (due to the tapered nature of the port). In good quality concrete this seal will hold back several thousand p.s.i. However, if the concrete is weak or the drilled hole is out of round, you can have a problem. In which case you want to use a Mechanical Port.

2. Mechanical Ports have dropped in price dramatically over the years due to inexpensive labor and cheaper materials from overseas. There is now little price difference between the Hammer In Ports and the Mechanical Ports compared to what there used to be. I have a personal affinity for Mechanical Ports because I used to make them in my father’s shop back in the early 1980s. They have a much larger surface area to create a seal and will hold more pressure than the concrete can take.

Make sure you seat the rubber all the way inside the hole. If it is partially outside of the hole, it can cause the surface of the hole to spall, chip, and crack. Setting it in at least ¼” past the surface of the hole will give you a great seal and reduce the chance of cracking the concrete unnecessarily.

Snug the ports down, but don’t over tighten. It is easier than you think to crack the concrete by over tightening (especially if you have drilled close to the crack or at a very steep angle).

Now that you have the ports installed, you are ready to clean out the crack by flushing water through the ports. I’ll discuss that in the next section.

Click below to read the previous articles in this series if you missed them:
5 Steps of Concrete Crack Injection - Overview
5 Steps of Concrete Crack Injection - 1. Drilling Holes
5 Steps of Concrete Crack Injection – 1. Drilling Holes (Continued)
5 Steps of Concrete Crack Injection – 2. Flushing the Holes

Click below to read next articles in this series:
5 Steps of Concrete Crack Injection – 4. Flushing the Cracks
5 Steps of Concrete Crack Injection – 5. Injecting the Resin

Want in-depth info on crack injection procedures and products?

Here it is. My favorite topic. Why? Because I have seen and heard some really stupid things concerning this. It is my pet peeve. It separates the technicians who care from those who are only going through the motions. And quite frankly, it can be the difference between a successful outcome and dismal failure - or at the very least an expensive call back.

When you drill holes you create concrete dust. The hammer drill bit literally chews up the concrete. Most of it comes out of the hole and falls on the floor. However, a lot of dust is left behind inside the hole. If it is not properly flushed out then it will mix with your polyurethane injection resin and make a thick paste. This thick paste can be forced into the crack and prevent the clean resin from reaching deep into the crack where it is needed. Most of the time you won’t even realize you have a problem. But there it is nonetheless. Waiting for the right conditions to allow water to seep back through the crack you thought you fixed.

How to avoid this? Simple - flush the hole out from the back using a very cheap flexible hose that attaches to your flush pump (you did bring a separate flush pump didn’t you?). Start at the highest hole and work your way down until clean water is flowing out of each hole.

Spraying water at the face of the holes may make it look clean, but it is not. There is still dust deep in the hole. Filling a water bottle up and squeezing it so that water shoots part way up the hole is not good enough. You have to have the water exit your hose at the back of the hole. This is the only way.

Exceptions? Of course there are. If you pull the drill bit out of the hole and water gushes out behind it in a steady stream you can skip this step. Otherwise, make sure you bring a flush hose with you. It has to be small enough to fit inside your drill hole. We make it easy for you. We make one and sell it for cheap (so don’t blame us if you get to your jobsite and don’t have one).

This is so basic it is silly. However, I have seen experienced technicians do the water bottle trick and try to explain that it is sufficient. I’m happy to report that those guys are working for your competitors now. Just make sure your guys don’t get lulled into laziness and skip what just might be the most important of these five basic steps:

1. Drill the hole
2. Flush the hole
3. Install the ports
4. Flush the crack
5. Inject the resin

Next up, installing the ports!

Click below to read the previous articles in this series if you missed them:
5 Steps of Concrete Crack Injection - Overview
5 Steps of Concrete Crack Injection - 1. Drilling Holes
5 Steps of Concrete Crack Injection – 1. Drilling Holes (Continued)

Click below to read next articles in this series:
5 Steps of Concrete Crack Injection – 3. Installing the Ports
5 Steps of Concrete Crack Injection – 4. Flushing the Cracks
5 Steps of Concrete Crack Injection – 5. Injecting the Resin

Want in-depth info on crack injection procedures and products?

Let’s face it, most of the structures you drill through will be full of rebar. Rebar is the steel reinforcement that gives the structure its strength. Concrete protects the rebar by shielding it from moisture, and the high pH of concrete keeps the rebar from rusting. However, once a crack forms it allows more water and environmental gasses to reach the area surrounding the rebar. Carbonation of the concrete can now occur which causes the pH to drop and the corrosion process to begin. The rust expands and takes up 15 times the volume of the un-corroded steel which causes tensile forces to work against the concrete eventually resulting in additional cracking and spalling. Hopefully, you will be called in to fix the leaks before much of this damage occurs.

Once you are on the jobsite, this slow process of decay does not really affect you (unless the concrete is spalling off as you drill). Your issue with the rebar is that it will stop your drill bit from penetrating the crack. The cracks will often follow the rebar, especially if there is not an adequate coverage of concrete over the rebar. Shallow rebar is a huge contributing factor to cracks in concrete.

At this point, all you care about are two things. First, how do you know if you have hit rebar? Second, if you have hit it, what in tarnation do you do now?

After drilling many thousands of holes like I have over my career, you pretty much know when you have hit rebar. Here are a few things to lookout for:

1. Forward progress of drilling has stopped.
2. The sound of the drilling changes.
3. The quantity of drilling dust is reduced.
4. If you are not sure, put your hand out to catch some of the drilling dust coming out of the drill hole. Observe it for metal shavings.

1. Move further away from the crack and try again (adjust your drilling angle).
2. Move closer to the crack and try again (adjust your drilling angle).
3. Move parallel to the crack and try again.
4. Move to the other side of the crack and try again.
5. As a last resort, drill straight into the crack. This is not the ideal situation, but if you can drill deep enough to get an injection port installed, then you might be able to successfully seal the leak.

Now that the surface of your concrete looks like Swiss cheese, it is time to go get that bag of fast set hydraulic cement you brought along for just this purpose. Try to patch it up before you begin injection because some of those abandoned holes are libel to have hit pay dirt. If you don’t seal them up then you will have foam or resin leaking out of the holes.

Hitting rebar is not fun and can be frustrating. The key is to expect it and try to think three dimensionally. See if you can visualize what is going on behind the concrete. This is one of the keys to becoming a really good injection technician.

Click below to read the previous articles in this series if you missed them:
5 Steps of Concrete Crack Injection - Overview
5 Steps of Concrete Crack Injection - 1. Drilling Holes

Click below to read next articles in this series:
5 Steps of Concrete Crack Injection – 2. Flushing the Holes
5 Steps of Concrete Crack Injection – 3. Installing the Ports
5 Steps of Concrete Crack Injection – 4. Flushing the Cracks
5 Steps of Concrete Crack Injection – 5. Injecting the Resin

Want in-depth info on crack injection procedures and products?

I remember my first day on the job back in June of 1985. We were working nights in the MARTA subway tunnels in Atlanta, sealing leaks in the ceiling. They 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 straight forward 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 the job because it is manual labor and can be taught quickly. 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). 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 half way between your starting position and the wall.

How far apart to 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 give you an idea of how far the resin will travel.

Be sure to pull your 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 I will talk about what to do when you inevitably hit the injection contractors nemesis...rebar!

Click here to read the first article in this series if you missed it:
5 Steps of Concrete Crack Injection - Overview

Want in-depth info on crack injection procedures and products?

There are five basic steps to be done when injecting a crack in concrete that is leaking water. 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, Spetec PUR F1000 and AP Seal 500. 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 towards 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 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 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 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 that 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...

Click below to read next articles in this series:
5 Steps of Concrete Crack Injection - 1. Drilling Holes
5 Steps of Concrete Crack Injection – 1. Drilling Holes (Continued)
5 Steps of Concrete Crack Injection – 2. Flushing the Holes
5 Steps of Concrete Crack Injection – 3. Installing the Ports
5 Steps of Concrete Crack Injection – 4. Flushing the Cracks
5 Steps of Concrete Crack Injection – 5. Injecting the Resin

Want in-depth info on crack injection procedures and products?

When it comes to leaking cracks, Spetec PUR F400 is an excellent solution. This product is free of solvents and phthalates, which is much safer for our contractors to use. It's also NSF/ANSI 61 approved for use with potable drinking water. This allows contractors to fix leaking wall or floor cracks at water treatment plants. Spetec PUR F400 is also safe for use around water containing fish and other wildlife.

Spetec PUR F400 is designed to shut down leaks in concrete, brickwork, concrete sewers pipes and precast concrete. This product works very well with leaking hairline cracks due to its low viscosity. Spetec PUR F400 is very flexible after it sets up, which allows it to retain its bond if the concrete shifts or moves due to freeze/thaw cycles. When the concrete shifts, the grout continues to bridge the crack.

Want more information on Alchemy-Spetec leak seal products?

Today is our last day exhibiting at the No-Dig Show!  Visit us at booth #146!

Watch this video to preview a couple Alchemy-Spetec product demos!

Want more information on Alchemy-Spetec products?

Spetec PUR GT350 is an MDI based hydrophilic one component flexible polyurethane grout. It is used for many things, most commonly for leaking cracks, soil grouting and joint leaks.  This highly flexible grout works very well in wet moving cracks.  The flexibility of this grout allows it to bridge cracks if they're still moving.  Spetec PUR GT350 works very well in the soils behind leaking walls.  This product has a quick reaction time.  With very heavy water flows, Spetec PUR H100 Accelerator can be used for faster set times.

One of our customers did a big project with Spetec PUR GT350 for the city of Beaumont, TX. They had 200 manholes that had leaking joints and cracks. The contractor soaked backer rod with Spetec PUR GT350 polyurethane grout to fix the leaking manhole joints. Crack injection was also done on the precast structures. If you're a leak seal contractor, consider going after these very profitable types of large scale municipal jobs. If you'd like assistance in that matter (or any others), call us now at 404-618-0438.

Want more information on Alchemy-Spetec leak seal products?

We are proud to announce that we are currently exhibiting at the No-Dig Show in Palm Springs, CA. Visit us in Booth #146!

"NASTT’s No-Dig Show is the largest trenchless technology conference in North America, where professionals attend to learn new techniques that will save money and improve infrastructure. This show offers six tracks and 160 peer-reviewed, non-commercial presentations, including case studies detailing environmentally friendly trenchless solutions and cost-saving opportunities for municipalities and utilities. With over 190 exhibiting companies and multiple networking events, spend quality time with current colleagues/customers and grow your connections. Whether you’re a newcomer or a show veteran, NASTT’s No-Dig Show is the must-attend conference for underground infrastructure professionals."

Click here to read more about the No-Dig Show.

Reps Attending: Jim Spiegel, Thad Brown
Polyurethane Solutions Demonstrated: Seal Leaks, Stabilize Soil, Lift Slabs
Booth Number: 146
Address: Palm Springs Convention Center 277 N. Avenida Caballeros, Palm Springs, CA 92262 

Want more information on Alchemy-Spetec products?