Sealing Joints with Grout and Oakum

Whether injecting with a pump or a cartridge, it's always helpful to have AP Oakum on hand. Liquids will take the path of least resistance and oakum is very adaptable for controlling them. For example, joints are typically easier to inject than cracks, and precast joints are about as easy as they come in regards to injection work. They are also very common routes for water infiltration, whether in manholes, culverts, vaults, and tunnels. Since joint injection does not require the consistent pressure provided by electric injection pumps, you can often make these repairs with cartridges instead.

Simple and Effective Leak Seal Method

Time and time again, it is easy to look like a hero with nothing more than a cartridge of Spetec PUR F400, a handful of AP oakum, and a flathead screwdriver. Lastly, be confident. Don’t confuse high-flow leaks with high-pressure. When you're working less than 20’ below grade, you are only dealing with a few psi of pressure even if it is a high-volume leak.

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Sealing Steam Leaks with Polyurethane

One of the most high-tech veneer manufacturing companies in the United States chose Alchemy-Spetec to train their maintenance techs to stop a steam leak in their facility. You heard that right. Not liquid water, but steam leaks! Prior to milling the veneer, they heat the logs in a bank of steam vaults. Rather than tearing down/rebuilding these cracked, leaking vaults they opted to inject the cracks with Spetec PUR F400, a hydrophobic flexible polyurethane grout. Replacing the vault would not only have been a lot more expensive, but it would also have resulted in a costly interruption to their milling process. No one likes downtime.

Polyurethane Leak Seal Training

Saturday is the one day of the week that the vaults are offline, and that is when I conducted the complimentary field training for their employees, who had never done any injection work before. Within a few hours, they understood how to handle the grout, how to use the grout pump, and how to accomplish their injection work. They can now self-perform their crack injection as needed.

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I was a Machinist Mate in the Navy and thus almost all of my training was mechanically focused. One class I had was Electrical Theory for Mechanics. The quick summation by the Senior Chief instructor for it was "Electricity is magic and when the smoke comes out the show is over." Being on a submarine it was deemed a good thing to keep water and electricity separate. My first time ever using polyurethane chemical grouts was on a group of sixteen conduits entering a below-grade mechanical room. While electricians may understand the "magic" of electricity they often fall short as waterproofers. Combined with the fact the numerous electrical cables coming through a conduit can be notoriously hard to waterproof and it is a recipe for leaks and electrical problems. In this post, I'll share step-by-step instructions, along with a couple of photos from a recent job one of our customers completed in a San Francisco condo complex.

Oakum soakem is a kindergarten-skill level procedure that makes waterproofing these types of penetrations easy. I refer to this as fingerpainting with chemical grouts.

1. For PVC and HDPE pipe roughing the surface will increase the mechanical bond and is recommended.
2. Wet the application area.
3. Soak oakum in either Spetec F400, GT500, or GT380 resin until saturated.
4. Pack soaked oakum into pipe joint to be sealed. If necessary, pack multiple layers. Ensure it is under compression.
5. Allow grout to cure.

Often this is all that needs to be done, but it can be followed up with injection to fill the conduit if required.

1. Stab injection needle through the cured grout and oakum plug.
2. Inject grout.

Photo: Contractor on a recent job in San Francisco, addressing multiple conduit leaks with electric injection pump, a pail of Spetec PUR F400, and Oakum.

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Sealing Leaks in Concrete with Polyurethane

Water is RELENTLESS. Leaks appear in all kinds of structures, from underground parking garages to municipal treatment tanks to elevator shafts. Everything from fine hairline crack leaks to gushers can threaten the long-term integrity of the structure and surrounding property. Fortunately, pressure injection of polyurethane grout into the crack or behind the leaking wall (depending on the application) creates a durable and rugged positive side repair. A relentless solution to a relentless problem.

A wide variety of leak seal solutions are available to address almost any type of concrete leak. (Call the Alchemy-Spetec technical support team at 404-618-0436 for assistance in choosing a product for your specific project.)

Polyurethane Leak Seal Solutions - Crack and Joint Injection

Crack and joint injection products are generally used for smaller non-gushing leaks:

Spetc PUR GT380
Activates as Foam or Gel Depending on Amount of Water Added
Ideal for Manhole Rehabilitation

Spetec PUR GT500
Most Dry-Cycle Resistant Hydrophilic Grout
Ideal for Cracks with Intermittent Leaking

Spetec PUR GT350
MDI Based Grout
For Wet Dynamic Cracks & Joints

Spetec PUR F400
Flexible Hydrophobic Grout
Ideal for Dynamic Cracks & Joints

Spetec AG200
Acrylic Injection Resin
Used in Special Situations (Contact Alchemy-Spetec Support for More Info)

Polyurethane Leak Seal Solutions - Curtain Grouting

Curtain grouting products are generally used for gushing leaks or multiple smaller leaks in proximity:

Spetec PUR H100
Semi-Flexible
Ideal for Structures with Some Movement

Spetec PUR H200
2,050 psi Compressive Strength, Fastest Cure Time­­
Ideal for Soil Stabilization

Spetec PUR Highfoamer
50x Expansion
Cost Effective for Large Voids

Spetec Boom! Seal
Two-Component, High Expansion (35x), Hydro Insensitive
Used in Special Situations (Contact Alchemy-Spetec Support for More Info)

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What Causes Leaks in Concrete?

Imperfect Construction
Concrete construction is by no means a perfect science. New construction often requires Leak Seal treatment follow-up work. If the initial construction isn’t properly sealed at the time of construction, leaks are bound to appear sooner rather than later.

Weather and Wear
Concrete naturally decays over time. Exposure to extremely hot temperatures and extremely cold temperatures can take their toll over time. Even structures located in mild climates will begin to decay purely due to the aging process.

Unstable Soil
Unstable soil can undermine the integrity of concrete structures and cause cracks to appear. Loose soil has four main causes: soil erosion, poor compaction, freeze/thaw cycles, and biological decay. If soil is the main culprit, additional stabilization and slab lifting treatments may be required in order to prevent further cracks from appearing.

What is Curtain Grouting?

Curtain grouting is the process of injecting water-reactive resin behind the leaking wall in a grid pattern (from the negative side). The water on the other side mixes with the grout and cures to a solid mass covering the surface of the wall on the other side (positive side). In addition, you don’t have water pressure dislodging external “patches” over time, as can be the case with other methods.

Curtain grouting is often required when there are gushing leaks, multiple leaks in proximity, cracks cannot be identified, the walls are made of material that does not respond well to crack injection (such as masonry, stone, and CMU), or previous leak seal methods have failed.

The most well-known Alchemy-Spetec product for this application is Spetec PUR H100, a one-component, closed-cell, hydrophobic, water-reactive, solvent, and phthalate-free, low viscosity resin. If there are large voids involved, Spetec PUR HighFoamer (a similar product with a higher expansion rate) may be a more cost-effective option.

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Crack Injection Explained

Crack injection has many advantages over other methods.  For example, if you’re sealing a leak in a water tank, you can inject from the outside of the tank. So the tank can remain in service while you repair it. Having to dry a crack, like you do with epoxy resin, is not needed as this material reacts with water. The material also remains flexible at all times.

Crack injections can be applied in both vertical cracks and in horizontal cracks. With vertical cracks, it is imperative to start at the bottom of the crack and work your way up the crack until it is filled. This forces the material up and through the crack and will simultaneously push the water up and out as well. With horizontal cracks, injection can be started at either the left or right end.

Read more from Charlie Lerman's article Crack Injection Explained.

Curtain Wall Grouting Explained

Curtain wall injection is the process of drilling holes through a structure in a diamond pattern, then injecting the grout into soil on the other side. This procedure creates a curtain wall made of a resin/soil mixture that prevents water from getting back into the structure. It is often required if there are multiple cracks or leaks in a wall. Filling each individual crack may cause you to waste time following the water from crack to crack. Curtain wall grouting allows you to stop multiple leaks at one time and protects the structure on a long term basis.

This procedure was first performed in 1960 on a sewer manhole with a multiple leak problem. As described above, chemical grout was injected through to the outside of the manhole. This created a “positive side seal” (on the side the water was coming from), blocking water from penetrating the joints of the structure.

Read more from Charlie Lerman's article Curtain Wall Grouting Explained.

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Moisture and Coating Failure

When you look into why coatings fail, moisture is always in the top five reasons. It's often the main reason in below-grade structures. Coatings can act as negative side waterproofing even if that was not their intended purpose. Water and time are powerful forces, look at the Grand Canyon.

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Polyurethane Leak Seal Pumps

Alchemy-Spetec offers world-class Titan electric injection pumps for sealing both small and gushing leaks as well as filling voids behind and below structures.  We modify these pumps to optimize them for polyurethane injection.

IMPACT 440 Electric Injection Pump
The IMPACT 440 is an advanced electric injection pump that’s ideally suited for residential, property maintenance and small commercial applications. This pump is the industry standard.

PowrTwin 8900 Plus Electric Injection Pump
The PowrTwin 8900 Plus is favored by contractors who want to complete large application jobs in record time with high-profit margins.

Polyurethane Leak Seal Accessories

Alchemy-Spetec offers a wide variety of accessories for polyurethane leak seal applications:

High Pressure Crack Injection Valve
This crack injection valve allows you to control resin flow at the point of injection and turn an airless sprayer into an injection pump.

Flush Wand
Use the flush wand to flush concrete dust from the holes you have drilled for crack injection.

High Pressure F-Valve Assembly
Twin streaming is a technique in which you use a high pressure F-valve to inject resin AND water at the same time. As you can see in the photo, the F-valve has two supply connections – one for water and one for resin. The water and resin come into contact before they exit the coupler.

Oakum
AP Oakum is an oil-free dry jute rope that seals cracks and slows down gushing water during leak repair. Oakum can be used alone or in combination with Alchemy-Spetec leak seal resins.

Ports/Packers
Alchemy-Spetec offers pretty much all of the required ports/packers you could possibly need for your next chemical injection project. 

Waterstop Products

Waterstop products are designed to prevent leaks from occurring in new construction.

Injection Tube System
The Spetec Injection Tube System is used in conjunction with the Spetec PUR F400 or Spetec PUR H100 as a primary waterstop in cold joints and pipe joints. This system can also be used in retrofit applications for expansion joints and other wide cracks or joints measuring over 3/8 of an inch.

Spetec SST500
SST500 expanding waterproof strips are simply fastened onto an existing joint.  When in contact with water in a confined space, SST500 will swell and stop the infiltration. SST500 remains consistent in its performance throughout its life cycle and the flexibility allows it to fill voids and cracks in the immediate surrounding area.

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Why Repair Groundwater Infiltration in Concrete Infrastructure?

As outlined in our previous blog posts, Mitigating I & I - An Ounce of Prevention is Worth a Pound of Cure and Spend a Little on Infrastructure Infiltration Repair, Save a LOT on Wastewater Treatment Costs, there are many dangers associated with sanitary sewer overflows, lots of funds available for infiltration repair, and many dollars to be saved by choosing to repair high-volume leaks.

How to Repair Groundwater Infiltration

All of this begs the question: How are these leaks repaired exactly? The first step is to identify high-volume leaks in manholes, lift stations, pipes, and other sanitary system components. Monitor and compare peak vs normal flow rates. Inspect the infrastructure in question and look for gushing leaks. These leaks can be repaired with a small crew of about three people. A repair crew this size typically averages about two manholes per day (depending on manhole size and proximity).

On average, curtain wall grouting an 4-foot diameter x 8-foot tall manhole requires 5 gallons of Spetec PUR HighFoamer. On average, treating joints and pipe penetrations on an 4-foot diameter x 8-foot tall manhole requires 2.5 gallons of Spetec PUR GT380.

For more information on infrastructure infiltration repair, call the Alchemy-Spetec tech support team at 404-618-0438.

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The Cost of Wastewater Treatment

According to an article published by Water Technology Magazine (WaterTechOnline.com), the average cost to treat 1000 gallons of wastewater is $2.06. Let’s take a look at how that $2.06 adds up over time. A 10 gallon per minute leak in a manhole for example equals 5,256,000 gallons of water leaked per year. That adds up to a $10,827.36 per year ($902.28 per month) wastewater treatment cost resulting from that leak alone.

Repair Infrastructure Infiltration & Save Money

Let’s compare that to the average one-time cost to stop all the leaks in a 4-foot diameter x 8-foot tall manhole: $3000 or so depending on local labor rates. This relatively low repair cost is recouped in less than 4 months, considering the monthly wastewater treatment cost of $902.28. This equals $7,000 - $8,000 cost avoidance in the first year alone. In subsequent years, you’re saving the full $10,827.36.

Now multiply those number by all the manholes in your district with large leaks. The numbers are truly staggering.

More Info on Infrastructure Infiltration Repair

For more information on infrastructure infiltration repair, see our blog post Mitigating I & I – An Ounce of Prevention is Worth a Pound of Cure. If you’d like to discuss I & I issues with our experienced tech support team, call 404-618-0438.

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