Sewers can be aggressive to downright hostile environments for concrete. Composite and fiberglass manholes are becoming more popular due to their superior resistance to sewer gases. While chemically resistant, composite manholes still have penetrations and joints. And any structure with penetrations and joints is still susceptible to infiltration.

The good news is that your everyday go-to grouts for concrete manhole water mitigation work just as well on composite or fiberglass manholes. Spetec PUR Highfoamer is a single component hydrophobic semi-rigid grout that is ideal for curtain grouting behind and around leaking penetrations and joints. When it comes to crack injection for penetrations and or joints, Spetec PUR GT380 and Spetec PUR F400 have the flexibility and chemical resistance you will need for the tough sewer environment.

Industries and technologies change over time and Alchemy-Spetec offers a full line of grouts that can provide for your long-term waterproofing needs - whether for composite, fiberglass, concrete or brick manholes and lift stations. 

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Read through this list:

• Manholes
• Catch basins
• Drop inlets
• Wet wells
• The Grand Canyon

This is not a game of which one doesn't belong, as they all channel water and can cause erosion. The Grand Canyon is breathtaking. Likewise, washouts or sinkholes caused by leaking and neglected infrastructure are breathtaking - but in a completely different way. They're breathtaking in regard to the high costs of emergency repairs and the potential damage they cause.

This quote, from an article on KCCI.com, sums it up nicely...

“At first, crews resurfacing the pavement thought a large piece of machinery had fallen into a sinkhole 10 feet deep… It turns out an original clay storm sewer pipe had disconnected, leaking water for what appears to be a long time, eroding the earth around it.”

There is no downside to fixing these common infrastructure issues before they get out of control. Any repair costs are quickly offset by the reduction of sewer water requiring treatment. Who is not for lower sewer rates, a healthier environment, longer-lasting infrastructure, and fewer manmade washouts/sinkholes?

So why don’t we address infiltration more? It is as simple as the old adage "out of sight out of mind". Infiltration is a preventable and treatable sewage collection system problem. We have neglected our infrastructure for too long and we need to raise public awareness of the issue.

We at Alchemy-Spetec not only manufacture quality polyurethane chemical grouts for these types of repairs, but we also provide top-notch training and support for leak seal crews. Call 404-618-0438 and let us know how we can assist you in raising awareness about or repairing infiltration. We are all in this together.

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The Central Davis Sewer District (CDSD) is a publicly owned collection system and water treatment plant that serves three local cities in Northern Utah. With a new highway being constructed just outside their facility, a new pump station had to be installed on the premises. After installation of the new pump station, a large leak appeared in the manhole which caused it to fill up with about 10 feet of water. The CDSD contacted PolyFoam Solutions to see what could be done to seal the leaks. The PolyFoam Solutions crew pumped all the water out of the manhole and discovered that two of the manhole’s horizontal joints had large leaks. These leaks were allowing about 10-15 gallons per minute (over 20,000 gallons per day) of water to infiltrate the pump station.

Powerful Polymers

PolyFoam Solutions worked closely with Charlie Lerman, Alchemy-Spetec's Director of Technical Services for the Leak Seal Division. Together, they devised a plan to seal the large leaks using Spetec PUR F400. Spetec PUR F400 is a solvent and phthalate-free, water-reactive, hydrophobic, closed-cell, low viscosity, shrink-free, flexible, one-component polyurethane injection resin designed to stop water leaks. It is also certified to NSF/ANSI/CAN 61 (approved for contact with drinking water).

Painless Procedures

The crew drilled four holes around the lower manhole joint and then installed injection ports. As they pumped the polyurethane grout into the ports, it began to travel around the joint, sealing the leaks. Once the grout had traveled as far as it could from one port, the technician moved on to the next port until the entire joint had been sealed watertight. They used oakum to temporarily seal some of the larger leaks until the grout had time to cure. The upper joint only required 3 port injections due to the speed at which the grout traveled.

Rapid Results

The crew only took about 3 hours to completely seal all of the leaks and return the manhole to service. There was no way the leaks could have been left un-repaired due to the water treatment cost and the potential damage the erosion would have caused. Replacing the manhole would have easily cost three or more times the price of grouting. In this case, the community wins as many tax dollars are being saved.

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The Specialty Waterproofing with Chemical Grouts presentation explains and demonstrates how polyurethane chemical grout can be used to cut off leaks in structures. The presentation covers the following topics:

• Chemical Grouting Primer
  • History
  • Safety
  • Characteristics
• Utilization & Applications
  • Identifying Applications
  • Selecting a Chemical Grout
  • Epoxy & Hydraulic Cement
• Installation Techniques
  • Crack and Joint Injection
  • Curtain Grouting
  • Oakum Soakum
  • Equipment Overview

This one-hour CE/PDH accredited presentation is ideal for engineers who are interested in learning about next-generation leak seal repair methods for sealing leaks in structures, controlling inflow/infiltration, and more.

Click here and submit your info for a follow-up call on scheduling an accredited presentation.

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Alchemy-Spetec grout labs are a great way to learn about industry-leading polyurethane leak seal products and applications. These are usually half-day events featuring...

Classroom Polyurethane Leak Seal Training

• Safety Considerations for Polyurethane Leak Seal Work
• Crack Injection Products and Application Procedures
• Curtain Grouting Products and Application Procedures

Live Polyurethane Leak Seal Demos

• Concrete Crack Injection
• Curtain Grouting
• Pump Startup and Maintenance

Contact your local distributor of polyurethane leak seal products and ask them to schedule an Alchemy-Spetec grout lab at their location. To find a distributor stocking Alchemy-Spetec products near you, click your state on this interactive map. 

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One of the many joys of my job is going to all corners of North America and participating in unique projects. While I am a seasoned traveler, cement is not. Cement grout often requires heavy equipment. Shipping cement grout and related equipment can be expensive. While often not a concern for most projects, it is a driving factor for remote locations.

I have been involved with numerous projects in which cement grout would be an acceptable repair and more cost-effective than chemical grout - until the project location gets factored in. Dams are found in many remote locations. The very remote ones are often built using a temporary road that can handle heavy construction traffic. Fast forward some years and these roads no longer can support cement trucks or other heavy vehicles.

Chemical grouting equipment can easily be loaded into a pickup truck or even on the back of an ATV. While the material cost of polyurethane chemical grout is more than cementitious grout, getting polyurethane materials and equipment to a remote site can be a lot less expensive.

Lightweight polyurethane is much easier to mobilize with a small to non-existent footprint. This means it is less disruptive to sensitive sites. (Seawalls are a good example where chemical grouting can be done without tearing up the home owner’s yard with heavy cementitious grouting equipment.)

There are many factors to consider for every grouting job. It helps to have the Grout Geek and Alchemy-Spetec in your corner to help design the right plan for your project.

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Polyurethane chemical grout injection can be a bit of a Pandora’s box at times. So, what can be done to help combat some of these uncertainties? Well, how about the easiest and most cost-effective solution first. Oakum! Not only is it amazing what you can accomplish with it, but it is vital to have on every job. YES, I SAID EVERY JOB.

There are only two things that have to happen for successful water mitigation. One, get the grout to the right location. Two, keep it there long enough to react. With tight cracks, it can be difficult to get the grout to travel in the crack, but once you get it there it is good to go. With wide cracks or high flow leaks, getting to the right place is easy, but keeping it there long enough to set up can be challenging.

You can use oakum to control grout and keep it where you want it in the crack or joint. Remember we are doing the injection work to stop the flow of water, so let’s make the least amount of holes possible in the concrete. But what does that have to do with oakum? Cracks are irregular, and often have sections that are wider in some sections. When this wider area is at the surface it can allow an easy escape path for a grout under pressure. That means you are wasting grout and not getting it where it needs to be, deep in the crack. Sure, if you have raw resin coming out of the crack you can just wait for it to cure. Once cured you cannot reinject that packer, so it is best to surface seal that crack and stop or slow down the loss of grout. This allows you to continue effective pumping into the crack or joint.

If the crack or joint is wide, grout impregnated oakum can be packed in place. While messy, this is the equivalent of finger painting with chemical grouts and is an easy process.

If you're thinking "I have rags, I don’t need oakum", think again. Oakum is stronger, can be pulled apart into just a few fibers if needed, and can be stuffed into very tiny defects where rags cannot fit.

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A large Mid-Western aluminum manufacturer was losing water from all of its quenching tanks. Losing 3 million gallons in half a year can be expensive, not to mention the massive effect that volume of water can have on soil and the structures it supports. So, they reached out to one of their trusted maintenance contractors, who in turn came to Alchemy-Spetec for guidance on how to efficiently mitigate the leaks with minimal downtime. 

Powerful Polymer

After consulting with Alchemy-Spetec, the contractor injected Spetec PUR F400 to seal the leaking cracks. This material is a solvent and phthalate-free, water-reactive, hydrophobic, closed-cell, low viscosity, shrink-free, flexible, one-component polyurethane injection resin designed to shut off water leaks.

Painless Procedure

Concrete crack injection with polyurethane resin is a five-step process:
1. Drill the injection holes.
2. Flush debris out of the holes with water.
3. Install the injection port.
4. Flush the crack with water.
5. Inject the resin.

Rapid Results

The crew repaired leaks in one tank at a time with no manufacturing delays. This meant no production interruption. The work was done at a fraction of the cost of replacing the tanks.

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Like with most issues, there is no one final answer, but let’s weigh the pros and cons. An easy one is cost: two-component urethanes are significantly more cost-effective than a single component IF you already have a rig to properly handle them. Keep in mind, not many leak seal contractors typically have a rig.

Speed: let’s talk reaction time. While the single component products can have their set time field adjusted, two-component products will almost always react faster. This is helpful when you have gushing leaks, but often you want to give your grout a longer time to migrate and permeate before they react to ensure you get the whole leak. Remember, 99% waterproofed is 100% leaking.

Both types of grouts are isocyanate-based and are closed celled. They both are highly resistant to chemicals, and neither are UV stable. The two-component grouts are always hydrophobic whereas the single component can be either hydrophobic or hydrophilic. In general, most two-component urethane grouts are rigid or semi-rigid. On the other end of the spectrum, single component polyurethanes can be a gel, a flexible foam, a semi-rigid foam, or even a rigid foam.

So, with all that said, single component foams are the traditional choice for leak seal. When it comes to crack and joint water mitigation, flexibility is key and that rules out most of the two-component foams. When we look at curtain grouting, both can be very effective and there can be a substantial cost saving when it comes to two components. But a downside of using two-component is the shorter set time and thus less travel.

In summation, for leak seal, single component grouts can do everything that is needed and are the typical grout of choice.

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Newcomers to urethane grouts often cut their teeth on these two terms, but the industry in general struggles with the understanding of what they are, and when to use hydrophobic vs. hydrophilic polyurethane grouts. So, I will cover the differences and then point out what I feel is a much more important conversation about polyurethane chemical grouts.

Hydrophobic

• Cured States: Rigid, Semi-Rigid, Flexible Foam
• Reaction: Requires Water
• Requires Accelerator: Yes
• Elongation: None to 100%
• Wet/Dry Cycling: Unaffected
• Adhesive Bond: Good
• Pumped and Handles as: Single Component

Hydrophilic

• Cured States: Flexible Foam or Gel
• Reaction: Requires Water
• Requires Accelerator: No
• Elongation: None to 300%
• Wet/Dry Cycling: Can Dry Out
• Adhesive Bond: Superior
• Pumped and Handles as: Single Component

Somehow, the industry has erroneously assumed hydrophobic means: "fears water and pushes it away". While at the same time assuming hydrophilic means: "loves water and draws it in". There are some truths in these statements but they are only the core and are wrapped in misconceptions.

Misconception One: Water Loving and Water Fearing

Both grouts require water to activate and yes, the hydrophilic grout can incorporate more of the water into its cell structure, but both grouts will push water away when they have reacted with enough water to polymerize.

Misconception Two: Hydrophilic Grouts Dry Out and Shrink Without Water

A more accurate statement would be that cured hydrophilic urethane grouts can dry out and shrink in an arid environment. Concrete normally has a relative humidity of around 60% which will keep a hydrophilic foam hydrated. Soils can vary in their relative humidity but most often have enough moisture not only to keep a hydrophilic grout hydrated but also enough to polymerize a hydrophobic grout without the need for added water.

Misconception Three: Hydrophilic Grouts Have Better Adhesion

It is 100% true hydrophilic grouts have better adhesion in ASTM lab testing, and I did just list them as having superior adhesion. But, in my twenty-plus years in construction, I have never seen a grout job performed under laboratory conditions. Adhesion requires a clean surface for bonding. During crack injection, surface prep is a water flush in a crack we cannot see. So clearly it would be silly to believe we have a pristine surface inside the crack to adhere to. So yes, in a lab, hydrophilic grouts adhere to concrete better than hydrophobic grouts. In situ, both have a weak adhesive bond and both rely on their compressive and mechanical bonds much more than on an adhesive bond.

So, it's important to understand there is much more to grout selection than just hydrophilic and hydrophobic. I would estimate around 60% of chemical grouters only chemical grout a few times year. This can make product and methodology selection very difficult. That is why I am here with the Alchemy-Spetec team to help navigate you through these critical nuances. Call us at 404-618-0438 for technical assistance!

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