Alchatek Blog

As we move toward a more clear definition of the Spetec and AP product lines representing our Leak Seal and Geotech product lines respectively, we're making a couple of product branding adjustments effective this week (or as soon as current stock is depleted).

AP Seal 500 will be rebranded as Spetec PUR GT500.  We are also introducing a water-activated semi-rigid polyurethane foam injection resin to the leak seal line which will be known as Spetec PUR H200.  Both of these products feature NSF/ANSI 61-5 approval for contact with drinking water. 

Spetec PUR GT500 is the exact same AP Seal 500 product you know and love, but rebranded to fit in with the Spetec leak seal product line.  This single component, low viscosity, flexible hydrophilic polyurethane injection resin is optimal for sealing hairline cracks, pipe penetrations, and joints in concrete structures.

Spetec PUR H200 is a single component, water activated, hydrophobic, low viscosity, closed cell polyurethane injection resin. Because it expands twice as much and (with the right catalyst) sets up 2.5 times as fast as the Spetec PUR H100, it's an ideal leak seal solution for quickly cutting off high-flow, underground leaks.

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Are you a property owner/manager looking for a geotech contractor to help you with unstable soil, sinking slabs or structures, etc?  As a leading manufacturer of polyurethane lifting and stabilization products, we sell to contractors all over the United States.  Wherever your property is located, we likely know a contractor in your area who can provide an estimate for repairing your geotech problem. 

For a brief overview of the types of services these contractors may offer, see the video below...

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A few years ago, we were asked to do a product demonstration for the Utilities division of Orange County, FL (which includes Orlando). Truthfully, I have dealt with Orange County since the mid 1990’s. They have a crew that does infiltration grouting among other things.

We were supposed to demonstrate our product on a fairly slow leak in a manhole. Not by design, but this was the leak they were scheduled to fix in the time frame we had scheduled the demo. Originally, they asked me to bring 5 pails of AP Fill 700. I also brought both our slow and our fast catalyst.

When I showed up in the morning, they told me they found a different leak which was a gusher. They asked if I had about 10 pails. I told them I only brought five. They said, “we’ll try your stuff first, then we'll finish up the leak with the current product we are using.”

We showed up to the jobsite and Tom, who has been doing leak seal for many years, said basically the same thing. “That’s all you brought?” Tom was quite a skeptic - at first.

They popped the lid off of the manhole and revealed a gusher at the bottom – about 12 feet down from the roadway and leaking probably 15 gallons a minute. The county performs what is called “Point Grouting”, which is a process where a pipe is driven from the surface down to the area near the leak. Polyurethane grout is pumped through the pipe to fill up the void and seal the leak. Tom expected to use between five and ten pails of grout.

We catalyzed the resin with a maximum dose of our fast catalyst. Tom started pumping. I had my fingers crossed hoping that he had the injection pipe in the right location. He did. The foam started coming out of the defect in the bottom of the manhole within 30 seconds. By the time he had pumped half of a 5 gallon pail, the leak was completely sealed. Tom went from a skeptic to a believer in less than five minutes. “I want some more of that, boss!” he said to Paul Morrisson – Utilities Supervisor.

Paul summed it up best – “Based on our extensive prior experience, we expected to use five to ten pails to stop this leak. With AP Fill 700 we were able to do the job with 1/10th that amount of material. Alchemy-Spetec product will save our crews a lot of time and labor and save the taxpayers of Orange County a lot of money.”

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Are You Smarter Than a Fifth Grader?

Jeff Foxworthy often asks if you are smarter than a fifth grader. Well if you're not, don't worry about it; you're probably still capable of estimating the amount of foam needed to raise a concrete slab. Through a combination of easy calculations, product information, and some site considerations, you should be able to estimate your slab lifting materials without too much trouble.

First of all you need to think about the basic volume calculation. How many square feet of slab are you jacking, how much do you need to lift it, and is it the whole slab being lifted or is it just one end of it? Calculate the volume (length x width x depth), adjust for the percentage of the slab being lifted, then compare it to the expansion properties of the injection foam in order to determine how much you need.

Beyond the geometry required to estimate lifting the slab, you must now take into account some job specific considerations. This is where it becomes critical to qualify the volume of material included in your proposal. And just as important, this is where you need to make sure you have included enough so you get the job done right and don't have to go back to the customer asking for more money. Sometimes that's unavoidable if you encounter surprises; but if you keep a few considerations in mind this can often be avoided.

Soil Compaction

Isaac Newton's third law of motion determined that for every action there is an equal and opposite reaction (or was that Wayne Newton, ha?). If you are trying to lift a slab, a porch, or a pool deck on ground with poor compaction or water issues, the foam will compact the soil until it is dense enough to support lifting the slab or deck. And the heavier the object, the more densely the ground will have to be compacted. Make sure to measure the soil conditions (using a penetrometer or probe) and adjust your material estimate accordingly.

Size / Shape of the Object Being Lifted

Extremely heavy objects can be lifted with polyurethane foam using a small amount of pressure and material. Often times the most difficult lifts are the smaller objects. Something with a small footprint, like some front steps or a stoop can be very dense and frustrating to lift. Injected material is going to seek the path of least resistance until it is contained enough to generate the lift. For a front stoop, the path of least resistance is usually going to be out the sides; meaning lost material and more cleanup. Proper injection techniques can contain the escaping material, but it is advisable not to underestimate your material on an innocent looking small job.

Voids

Sometimes the ground can be well compacted but due to erosion factors (usually misdirected water runoff) slabs and other foundation type settlement can occur. Although the object has only settled a few inches, sometimes a much deeper void can be hidden from view. In these cases it is advised to use a probe through a hole drilled in the slab in order to get an idea of the depth of the void. Personally I have seen voids that went down 20 feet, so do not ever assume anything. Most void depths are pretty easy to determine and you will get the optimum expansion out of your material when filling them. But once again, calculate the extra volume to fill it and spell it out in your proposal.

Typically for a lifting job with no other considerations aside from lifting volume, we recommend adding an additional 10-15% onto your material estimate to cover yourself. Just make sure you do a thorough evaluation of the conditions and possibilities so you don't underestimate the job and have to go back to the property owner with your hand out. 

If you haven't already, make sure you read this blog post on our custom Alchemy-Spetec material estimating app for your smartphone.

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Any successful slab lifting job begins with a thorough site evaluation. Some new jobs are like previous jobs, some are a little bit similar, and many are a completely new experience altogether. A site evaluation is not limited to, but should include Identifying the Cause of Slab Settlement, Gathering Information, Identifying Potential Hazards, and Visualizing the Mobilization.

Cause of Slab Settlement

Determining the cause of settlement is usually the first step in beginning your evaluation. The cause can be any number of things such as erosion, ground water, sink holes, poor compaction, and buried debris that breaks down over time. Correctly identifying the cause will help you determine if slab jacking alone will solve the problem or whether a combination of lifting, stabilizing, and / or void filling will provide the permanent solution.

Gathering Information

The next phase should include gathering information from multiple sources. This includes dimensional information such as length and width of the slab; but also, the amount it has dropped, to help determine the volume of structural foam needed to lift the slab back into place. Make sure to bring your camera, notepad, and tape measure. Gather information from the property owner; find out about any known irrigation, electrical, water, or drain lines. Specifically, find out from the owner about any areas or features that need protecting around the injection site, the location of your rig, and all points in between where your crew may be working.

Identifying Potential Hazards

If the job is outside of a building, find out where the utilities are and have them professionally located. It's a lot harder to get paid when you have just drilled through the owner's power line or filled his landscape drains and fountains with foam. Additional information that may be available could include a soil engineering report, a structural engineering report, and reports from the builder of the structure. Don't forget a hammer drill, bits, and a penetrometer to determine soil compaction. Think about other issues that might create problems like slabs binding (concrete saw?), bent rebar from a settled slab, etc. Make sure you have considered all the tools you are going to need for the job and the cleanup.

Visualizing the Mobilization

After the data gathering is complete, it's time to visualize the job site as a whole and consider any challenges to mobilizing and physically reaching the areas that need lifting. Think about potential issues: How big is your rig? Is a trailer rig or a box truck rig going to face challenges getting into and out of the area? And once your rig is in place, do you have enough heated hose and pump power to get the required volume of material where it needs to go to do the lift?

Some of the above seem obvious but it's often the obvious things that get overlooked. Mistakes can drastically cut into your profitability and reputation. There's a reason pilots go through the same checklist prior to every flight. Sometimes you only get one chance to do the job.

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Understanding the causes of slab or structural settlement is key for the contractor to help identify potential opportunities for slab jacking with polyurethane.

Though there are many reasons for sunken slabs, we have identified the three main conditions that cause the settling issues we like to fix. These include erosion, poor compaction, and biological decay.

Erosion Often Leads to Concrete Slab Settlement

Erosion is the most common cause of settling and the most common reason for slab jacking. Poor drainage, improperly placed downspouts, leaking drain pipes, and broken water lines are common culprits. Water can either slowly erode soil over time, or very quickly erode away the soil beneath a concrete slab or structure causing it to settle.

Poor Compaction Can Cause Settlement & the Need for Raising Concrete

When backfilling on a jobsite, the site contractor is supposed to walk in backfill (drive over it with heavy equipment) and compact it in small lifts. However, this isn’t always done properly for one reason or another (inexperienced operators or people taking shortcuts). The result can be soil that will continue to compact itself and settle over time.

A great example of this is bridge approach slabs. These slabs are found on roads and highways all over the world. Bridges typically sit at a higher elevation than the roads that approach them. During construction, the final section of road (typically a concrete slab) is built on backfill to raise the elevation to meet the bridge. Over time, the slabs can settle due to poor or improper compaction. Compounding the problem is the fact that when a slab settles a little, the expansion joint opens up and allows water to get underneath the road, adding erosion to your compaction problem.

Biological Decay Can Result in Sinkholes and Sunken Concrete Slabs

Construction trash pits, buried trees, and other biodegradable materials all eventually break down. Sure enough, there always seems to be some corner of a building or a separate parking area or driveway that ends up right over it. These situations can range from slight settling to very severe.

Sometimes you have a combination of factors that cause settling. As we discussed in the bridge approach slab issue, poor compaction can lead to settling which will open a joint and allow water to compound the problem with erosion. Property owners and managers should not ignore these problems, or they will become more expensive to fix over time.

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Slab Jacking vs. Replacing Concrete

So, you're faced with a sunken concrete slab that could be repaired via complete replacement or being lifted back into place. How do you know which option to choose? Here are a few things to think about.

Raising Concrete is More Cost Efficient Than Replacing

If the slab is in good shape, and is of a reasonable enough size and thickness, it is usually going to be more cost effective to lift it back into place with structural polyurethane foam. Our PMC pumps can deliver the AP Lift series of foams as far as 400 feet away through heated hoses. And remember, wherever you deliver new concrete, you have to haul away old concrete.

More Environmentally Friendly with Polyurethane Concrete Lifting

Everybody wants to be green and take care of the environment these days, because it's the right thing to do. There is an environmental impact every time concrete is replaced. The cement manufacturing process is the second largest cause of greenhouse gas emissions in the world. Additionally, there is the issue of what happens to old concrete once it is removed. One would like to think it is recycled, but more often than not it ends up being dumped. Hopefully that would be in a landfill, but we've all seen piles of concrete rubble in places where it would be considered trash or pollution. It's worth considering. Meanwhile Alchemy-Spetec's AP Lift 430 and AP Lift 475 are so environmentally friendly they are NSF approved for contact with drinking water in their cured state.

Polyurethane Slab Jacking Requires Less Downtime

Last but not least, how long can a property owner or manager afford to have that area out of service? Consider a busy warehouse, an airport taxi way, or a bridge approach on a highway. There is an economic impact when those are out of service for replacement. It can be a couple days before new concrete is traffic ready. Wouldn't it be better to have it lifted in a few hours, and then back in service 15 minutes after the slab jacking is done? I know what I would want.

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A home or commercial building is only as good as the foundation it’s built on. And regardless of how well-constructed a structure may be, most foundations settle. That’s just a fact of life. Shifting soil compaction and many other environmental conditions that tend to cause settling, however, should ideally be stabilized before significant structural damage is done.

One or two minor hairline or shrinkage cracks shouldn’t necessarily send off any warning bells – though both merit monitoring. But multiple or widening cracks indicate more serious problems and may lead to additional damage. For the property owner, this can disrupt business, displace occupancy, and cause a domino-effect of infrastructure woes serious enough to break the bank. Or worse. Litigation can result if preventative action isn’t taken before loss or injuries occur.

These factors alone make acting sooner rather than later imperative. Stabilization and lifting are key solutions to consider in cases of foundation or slab distress. How can you know for sure if slab lifting or soil stabilization is needed? Watch for these five warning signs:

Bulging or Cracked Floors

It’s estimated that 60 percent of homes built on expansive soils result in shifting and heaving in all or even just part of the foundation. One can’t-miss sign of distress caused by wobbly soil compaction is buckling and bulging wood floors or evidence of cracking concrete in other types of flooring.

Cracked Walls

When soil moisture levels are all over the map, you can be sure that problems will ensue. Poor drainage, soil decomposition, naturally occurring conditions, nearby sewer line damage, underground aquifers – all can play a role in fluctuating soil moisture levels that lead to foundational settling. Cracked sheetrock or concrete walls are a warning sign that trouble is brewing underneath the surface.

Sticking Doors

When doors suddenly start sticking or won’t easily open or close, it’s a sign that either moisture levels are causing the door to swell or something in the structural frame has shifted. And that something might very well be the foundation.

Displaced Moldings

Look up toward the ceiling or down at the floor for moldings that may have gone wonky, jutting this way or that.

Leaning Trees, Fence Posts, Etc.

It’s hard not to notice a tree, fencepost, mailbox, or flagpole that is leaning like the Tower of Pisa. If you don't associate this abnormality with foundational distress, you should. It can be a sign of sinkholes – the kind that gape and maw without warning. If the site you're evaluating is in what is known as karst terrain, which about one-fifth of the nation is, it's susceptible to sinkholes. Likewise if there are abandoned coal or other mines, sewer construction or groundwater pumping nearby. All are signs that further investigation may be needed, pronto.

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Welcome to the 3rd and final part of my blog post series “Sealing Leaks on Remote Job Sites”. In Part 1 and Part 2 of this series, I described a remote leak seal job I assisted a customer with and the unique preparations it required. So to pick up the story where I left off - there we were, in the jungle, about a mile from our trucks. Of course we were doing our best to deal with the August heat and humidity. At least we had poison ivy, ticks, and yellow jackets to keep us company as we tackled these pipe penetration leaks on the aerial manholes.

As I mentioned, we removed as much of the old mortar from the pipe penetrations as we could. We also drilled our port holes at this time, about 5 inches apart and all the way around the pipe penetration. The port holes were drilled at a 45º angle, and located so that the injected resin would hit the pipe about midway through the penetration. Then we flushed out the areas and port holes with clean water.

Now it was time to seal it. We soaked oakum in the polyurethane and then gave it a quick dip in a bucket of water to get it activated. Then we packed it into the pipe penetration as deep as we could get and all the way around the pipe completely to form a back seal. Then we did it again forming another seal all the way around the pipe penetration but this time towards the outside wall of the manhole. Finally we injected the urethane into the ports working our way from the bottom to the top, completely around the pipe penetration.

For this application, AP Seal 500 was the right choice. It reacts when contacted by water, it's flexible, and it bonds tenaciously to concrete. Plus, its low viscosity allows it to get into tight cracks and voids to seal off leaks. If there is water present in the cracks, it can be injected straight. We actually injected it with water using a two chambered cartridge and static mixer. One chamber held the resin and the other was filled with water just prior to injecting. The reason we did this was because we were working during the middle of the day when sewer flow was the lowest. There was no leaking water present in the penetrations so we had to provide our own. Injecting with the water provided the “kick” to make the urethane foam expand and form an excellent seal between the front and back oakum gaskets we created.

Although it was not in the contract, we couldn't ignore the other small leaks through the manhole walls. Plus we wanted to help the county in return for their clearing the footpath to the manholes. These particular leaks were below the pipe penetrations and were constantly seeping sewage water. There were literally hundreds of yellow jackets swarming on the wet manhole face but they didn't bother us. To repair these leaks we drilled port holes that would intersect the cracks at an angle. As always, we flushed out the holes with clean water. As an experiment, we only put in a couple ports and then started injecting the same polyurethane; this time without additional water as there was already water present in the cracks. Sure enough, the low viscosity resin traveled throughout the cracks as it was injected and sealed off the areas where water was working its way through.

When we were finished, the manholes were completely dried out and there was no longer sewage leaking into the sandy soils beside the creek. It always feels good to get a job done when there's the added benefit of doing something to protect the environment. It also feels good when a project goes smoothly because you took the extra time to visualize it, plan the work, and work the plan.

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