According to the Guinness Book of World Records, the honey badger is the world's most fearless animal. With ultra-thick skin and top of the line fighting instincts, this creature is not to be messed with. It boldly goes where similar animals consistently fear to tread. 

Let's take a deep dive into why Alchemy-Spetec's smallest slab lifting system, The PolyBadger, is named after this incredible animal. As Alchemy-Spetec regional manager Andy Powell mentions in this previous blog post...

"The Alchemy-Spetec PolyBadger lifting system is tough and compact. This system is an affordable entry-level slab lifting option for new contractors, as well as an extremely portable addition to the experienced contractor’s arsenal. The PolyBadger is a lot less expensive than your standard 20-foot trailer rig. The setup is simple and requires minimal equipment. The entire system can easily fit in the back of a pickup truck!"

Like the Honey Badger, the PolyBadger lifting system is both Tough and Compact

The PolyBadger slab lifting system is durably built and designed to go where other lifting systems simply cannot venture. Here's a quick rundown...

• The PolyBadger is smaller in size than most of the competition, at 30" wide and 48" long. Now that's what you call portable!
• This is one of the few systems powered through a common 120-volt wall outlet (vs the usual 240-volt requirement). Compatibility with common wall outlets exponentially increases your location possibilities.
• Essential elements (heaters, electronics, auto calibrator) are self-contained and protected in the cabinet for extra portability.  
• The cabinet is constructed from powder coated carbon steel and the frame is constructed from carbon steel box tubing. 
• The entire system is very maneuverable, resting on two swivel and two fixed 6-inch pneumatic castor wheels.  The wheels are are filled with light weight polyurethane instead of air, so they don't go flat. 
• The hose is built to last with a Teflon core and a stainless-steel braid. The system can operate with up to 200 feet of hose.

One last very important point:

Honey badgers are also mentally tough. They've been known to build stools with rocks in order to get over walls even break through locks on food freezers! Nothing stops them! The PolyBadger system's auto calibrator provides similar qualities to keep it going through thick and thin. As Andy Powell mentions in this previous blog post...

"The genius of the PolyBadger is the auto calibrator. It keeps the flow of A-side and B-side slab lifting material on ratio, eliminating the possibility of crossover clogging in the gun or the whip hose. The two low-pressure transfer pumps and auto calibrator are literally the only moving parts in the whole system. That means less downtime, less maintenance, and more productivity on the job."

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Salt corrosion, tidal action, currents, boat wakes, storm surges and sometimes hurricanes all deliver a constant beating on the seawall. Contrary to popular opinion, many of the forces also come from the side of the wall facing the land. Did you realize that rainfall/storm events create more hydrostatic pressure than rising and falling tides? Every time it rains or the irrigation system runs, and every time the tide goes out; all of the groundwater above the waterline needs a place to vent or equalize. Massive pressure can build up if that water is trapped, making it impossible for it to drain into the sea or storm water system. That is a recipe for disaster which can easily be avoided with proper surveillance. Let's take a look at some of the external signs a seawall is in need of repair... 

Small Sinkholes Near the Wall

In landscaped areas, evidence of soil erosion is often quite obvious.  In this photo you can see that there is a small sinkhole developing at the inside corner of the seawall.  Some types of grass will actually keep larger sinkhole from being seen.  So check thoroughly.

Voids Near the Edge of the Wall

Obvious settling soil should have gotten the property owner’s attention in this case.  Too often, they ignore the warning signs until something more catastrophic occurs.

Cracking Concrete

Here, ground penetrating radar revealed loose soil zones beneath this concrete apron outside of a fish processing facility.  The steel sheet pile walls were losing soil and huge voids had developed.  Evidence of cracking concrete was not enough to get their attention as is often the case.  However, when a Lull forklift went through the slab, everything but foot traffic was prohibited from being on the apron.

Damage to Structures Up to 100 Feet Away

Capillary pathways of leakage can be found over 100 feet away from the visible leak, depending on the soil matrix.  The back of this pool deck had dropped about 6” already as the yard slumped towards the leaking seawall.

Causes of Seawall Damage – An Overview

Correct construction of a seawall will include a drainage system to handle the bulk of the water that comes from rain in addition to check valves, weep holes, or seams to handle the daily influx and outflow from tide and wave action. Although these systems are designed to retain the soil behind the seawall, over time the materials degrade or can be disturbed by settling.

This is a direct symptom of normal wear and tear from the natural environment and is unavoidable. The result is a loss of soil and the inevitable sinkholes and / or low spots that will occur along the wall. Other times, the weep holes and vents become clogged and the water has no way to escape except to force its way down and out from underneath the base of the wall. When this occurs there will again be sinkholes and sometimes wall failure.

Conclusion

When signs of sinking ground are observed, you can almost be sure there are voids below that are that are not seen from the above the surface easily and are indeed dangerous. Sometimes these voids can extend below an adjacent patio, dock, or pool deck, causing those to sink and crack as well. The key to keeping those problems at bay is to actively anticipate them.

If you live along the water, it is always going to be man against nature. That seawall is keeping your property from damage and from disappearing altogether. The key to extending the life of your seawall is the advanced polyurethane technology from Alchemy-Spetec. For more on the repair process itself, read An In-Depth Look at Polyurethane Seawall Repair. It's fast; clean, easy to install, and most of all, effective.

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In the previous post, An In-Depth Look at Polyurethane Seawall Repair – Part 1, we looked at causes of seawall deterioration, typical evidence of deterioration to look out for near seawalls, and the three most common seawall repair options: excavation, cement grout repair and polyurethane repair.

Now we’re going to take a deep dive into the qualities, applications and advantages AP Fill 700 – the Alchemy-Spetec product most typically used for seawall repair. We’ll also share a case study on a seawall crisis at an upscale marina that was resolved by contractors using AP Fill 700.

AP Fill 700 Advantages

AP Fill 700 is a single component, water activated, hydrophobic, low viscosity, closed cell polyurethane injection resin. In addition to seawalls, it’s a proven polyurethane concrete crack sealant for all types of structures. From our experience advising contractors, we’ve found it to be the most cost effective method for repairing seawalls.

Here are some of the advantages it has over other polyurethanes:

Lowest viscosity on market

AP Fill 700 has a viscosity of 110 to 130 cps. This allows for getting into thin cracks.

Closed cell, 0% permeability

The closed cell structure of this foam allows for ZERO percent permeability. No compromising of the repair material to worry about.

Adjustable set time

Adding various amounts of catalyst to adjust the set time allows for custom application of the material to address the specific nature of the seawall problem. A longer set time allows for the material to permeate and soak in around the structure before setting up. A shorter set time makes the material set up more immediately, which may be appropriate when there are large voids to fill or gushing leaks to stop.

Single component

This particular product does not require a “B” side to react with before setting up. This allows for simple, efficient installation.

Phthalate free

Some companies use phthalates in their polyurethanes. Because of their environmentally unfriendly nature, it’s not even legal to manufacture phthalates in the United States. Companies using them have to import them from overseas. Needless to say, AP Fill 700 does NOT contain phthalates – a known marine pollutant.

Approved for contact w/ drinking water

As mentioned in the previous post in this series, AP Fill 700 has been NSF certified for contact with drinking water. So, obviously installation in recreational or commercial bodies of water is no problem from an environmental perspective. Read more about NSF certification in the blog post Alchemy-Spetec's NSF Certification Spells Environmental Protection.

High bonding characteristics

Once AP 700 is installed, it’s NOT coming off. The adhesive qualities are unparalleled. This contributes to the vast advantage polyurethane has over cement grout when it comes to durability.

More about AP Fill 700

This material is designed to be efficiently delivered into all sized gaps and eroded depressions. It reacts with water or moisture in the soil and expands to fill the voids. It’s compatible with any seawall material: concrete, steel, vinyl, etc. And it permeates the most sandy of soils to form a solid, strong, watertight mass. It sets in less than 10 minutes. By being impermeable to water once in place, the likelihood of future erosion is vastly diminished. 

AP Fill 700 Applications

In addition to seawall repair, there are many other general applications for AP Fill 700. Here a few to keep in mind…

• Cutting off low and high flow leaks
• Concrete void / crack filling for all structures
• Cutting off underground water flows
• Soil stabilization
• Filling voids under concrete slabs
• Encapsulating contaminated soils

Durability

Leading experts in the polyurethane industry predict that this material lasts for hundreds of years once installed. Polyurethane is made from similar materials as plastic. There’s a reason why people campaign against the dumping of plastic waste in the middle of the ocean: it will be there forever. The edge of the ocean, properly installed as part of a seawall repair, is a much better place for it. And, yes, it tends to last forever.

Powerful

If needed, AP Fill 700 can quickly shut down leaks of thousands of gallons per minute. Rapid expansion makes it great for filling voids, wide cracks, pipe joints, pipe penetrations. Originally developed over 30 years ago, and continuously improved since, this technology has one of the longest histories of success in the field among uses of polyurethane foams

Efficient Installation

Results are immediately clear due to the visible exiting of sea water when the foam is injected. The low viscosity allows it to be injected into hairline, expansion joints and smaller cracks as well. AP Fill 700 is field proven in “curtain grouting” (earthen dam seepage protection), and consolidating loose soils.

Case Study

Let’s close out this two part series with a look at polyurethane seawall repair in action…

Situation

Owners of an upscale marina in Riviera Beach Florida noticed cracking in the slabs outside of their main boathouse. They also noticed that the slab had settled in several areas. The slabs in question were subject to heavy dynamic loads as a large forklift traversed the area, bringing 40' motor yachts in and out of the boathouse. Contractors came in and did a site evaluation, drilling holes to probe beneath the slab and also a sub surface investigation of the seawall to see if soils were being lost.

Solution

Most of the joints in the seawall were leaking sandy soil out - resulting in a void beneath the concrete slabs, which then cracked and settled. AP Fill 700 was specified to seal the concrete panel joints. It was injected behind the panels in the area of the joints, both vertically through the concrete, and horizontally from the water side of the panels. Proper venting was then installed to relieve hydrostatic pressure.

Results

The sandy soils have been stopped from escaping from behind the seawall. The concrete slabs were then lifted back into place with a combination of helical piles and AP Lift 475. There are no longer any voids beneath the slab so it is not flexing and cracking any longer. This marina was saved from a much larger, more catastrophic failure.

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The Spetec PUR H100 Hotshot Cartridge contains Spetec PUR H100, a one component, closed cell, hydrophobic, water reactive, solvent/phthalate free, low viscosity polyurethane injection resin for stabilization and water cut-off of large water leaks. The cartridge packaging is ideal for small jobs in locations that prohibit the use of pumps.

Advantages:

• Single component cartridge.
• Good compression strengths.
• Rapid set time.
• No volatile solvents.
• Cures to rigid foam.

Applications:

• Water cut-off.
• Dams.
• Manholes.
• Storm pipe joints.
• Box culverts.
• Limited access areas.

For details on preparation, application instructions, required tools and more, please download this Spetec PUR H100 Hotshot Cartridge datasheet.

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Chemical grouts are commonly injected into leaking cracks and joints to stop the flow of water, sealing off cracks and filling voids. This procedure can be performed in both wet and dry situations, in potable water or wastewater tanks, and in a variety of other structures where water is leaking.

Procedure

Identifying and Preparing the Structure

• Clean crack surface using a wire brush, a grinder with wire cup wheel or other mechanical means, to remove mineral deposits, coatings or other debris. Pressure washing of the surface is also an option. If sever contamination exists, a chemical cleaner may be used, but must be flushed or neutralized before proceeding to the next step.
• When addressing wide cracks, use Oakum, hydraulic cements or epoxy gels as a surface seal over the crack prior to injection to contain chemical grout in the structure. When addressing high flow leaks, use Oakum soaked in chemical grout. Soak oakum in chemical grout and insert into the leaking crack or joint with a screw driver or similar tool. This will slow the water flow.
• pH notice: water used to activate Alchemy-Spetec chemical grouts must be in the pH range of 3-10 to achieve optimum performance.

Injection Port Spacing and Drilled Holes

• Port spacing is determined by the width of the crack: 3-4 inches apart in tight cracks and up to 24 Inches apart in wide cracks. Staggering ports from side to side (stitching) is always recommended.
• To intersect a crack at the mid-point, drill injection port holes toward the crack at a 45-degree angle, at a distance of one-half the thickness of the concrete. Example: In 12-inch-thick concrete, drill the injection port hole 6 inches back from the crack at a 45-degree angle to ensure crack is intersected at mid-point (longer drill bits may be needed to reach mid-point). See Diagram.
• Drilled holes should intersect the crack or joint at the midpoint, so the chemical grout can enter the crack in the center of the concrete and expand in both directions sealing the entire crack, filling any voids and micro cracks in the structure as the material expands and cures.
• Drilling injection holes is commonly performed using 3/8, ½, or 5/8-inch diameter drill bits.
• Flush drilled holes with clean water to remove dust and debris before inserting drive in port or mechanical packer.

Installing Injection Ports / Packers

• Various types of drive in ports and mechanical packers are available in the market.
• Drive in ports should be driven/hammered into the drilled hole until snug.
• Once the port is snug in the hole, insert a grease or zerk fitting into the port. Insert mechanical packers into the drilled holes until the top of rubber sleeve is just below the concrete surface.
• Tighten the packer using a wrench or ratchet, turning clockwise until firm. Do not over tighten.
• Install each port before injection but leave the grease coupler/zerk fitting off so you can monitor the travel.
• Avoid hammering on the grease coupler/zerk fitting.

Equipment and Equipment Set Up

• When using chemical grouts that are water reactive, use two separate pumps: one for water and the other for chemical grout. Caution: Never allow water to enter the chemical grout pump.
• Flush out the chemical grout pump and lines prior to use with an approved pump cleaning agent. This will ensure that the pump has no moisture in the system. Repeat flushing procedures when injection operations stop for a prolonged period of time.
• Pump hoses should be equipped with a high-pressure ball valve assembly. This allows easy connection to the injection port and an on-off grouting operation.
• Keep injection pump pressures low at the beginning of injection and increased slowly as needed to achieve full grout penetration. Extra high pump pressure may result in cracking or spalling of the concrete.

Flushing the Crack Prior to Injecting

• Flush the crack prior to injecting chemical grout to ensure that the crack is free of debris, that injection ports have intersected the crack, and that there’s enough water to cause the resin to react.
• Begin injecting water at the lowest port on vertical cracks or at one end (and then work across) on horizontal cracks. Continue injecting water until the crack has been flushed and clean water appears.

Injection of Chemical Grout

• Inject the liquid (catalyzed) resin into the injection packer.
• When injecting a vertical crack, start at the bottom and work upward as the material seals the crack.
• When injecting a horizontal crack, start at one end and work across the crack.
• REMEMBER: Keep pump pressures low at the beginning of the injection process and increase slowly as needed to achieve full grout penetration. Extra high pump pressures may result in cracking or spalling of the concrete.
• Inject at a rate that allows material to travel and completely seal the crack. Once you see material seep out at the adjacent port, pause injection and insert a grease coupler/zerk into that port. Then resume injection on the existing port.
• Advance to the next port when movement of material has stopped on the existing port, or when material is exiting the crack at an excessive rate.

Completion and Clean-up

• After fully injecting the crack with chemical grout, attempt to re-inject water into each port to ensure that the crack and drilled holes have been completely sealed.
• Next, remove each injection port/packer by pulling the port/packer out of the structure, or by drilling them clear to below the surface by 3 inches or more.
• After removing the ports/packers, fill the injection holes with hydraulic cement, non-shrink grout or epoxy gel material.
• Remove any wasted cured resin, used ports/packers, and construction debris.

COMMON MISTAKES TO AVOID

• Drilling too close to the crack can cause spalling of concrete.
• Drilling too close to the crack will not allow material to seal entire crack, which can result in re-occurring leaks.
• Injection of cracks with manual equipment (ex. grease guns) will not produce enough volume and may cause extreme waste and injection failure.
• Poor preparation of wider cracks may cause material waste, lea–ding to re-occurring leaks.
• Injection pump pressure which is too high can cause spalling and damage to the surface.

Chemical grouting for leak-seal applications can provide contractors a specialty repair service that will always have relevance and demand in below-grade structures and water-holding structures. By following these steps for product, packer, and pump selection, you will be on the right path to a successful leak-seal repair. For more details and information on the leak-seal methodology, please contact a knowledgeable Alchemy-Spetec team member.

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Once the material is selected, an appropriate piece of equipment must be selected for dispensing the material. For most polyurethane injection resins, single component high-pressure piston pumps are required. These are typically electric airless design, but can also be pneumatic, drill-operated, or hand powered. Alchemy-Spetec offers the full line of Titan pumps with various ranges of pressure and volume. The Titan 440 is a good pump for small injections, or to act as a water flush pump to clean drill holes and to ensure drill hole intersects the crack or joint. For higher outputs, it is recommended to use the Titan 640 or PowrTwin 8900. These pumps will be much better equipped for large volume applications such as curtain grouting, or for single component soil injection applications. For small cracks and joints, Alchemy-Spetec offers the Drill Pump. The Drill Pump is drill-operated and capable of handling pressures as high as 5000psi. It is easily maintained and produces very minimal waste due to the small hopper size and mixed batches. For acrylic injections, a stainless-steel pump, the Alchemy-Spetec Gel Pump is required. Due to the oxidizing nature of the B-side sodium persulfate, stainless equipment is required. 

The coupler at the end of the hose set will be dependent upon the type of zerk fitting discussed in part 2 of this blog series. A button-top valve requires a sliding coupler, the Alchemy-Spetec ACP-2204, or the standard zerk coupler, ACP-2201. It is always recommended to have several couplers on-site as the injection grouts will eventually cure in the couplers and prohibit the passage of material. It is also recommended to keep a spare piston kit or packing kit for any pump and to have received training on the appropriate replacement technique should it need to be changed. 

Chemical grouting for leak seal applications can provide contractors a specialty repair service that will always have relevance and demand in below-grade structures and water-holding structures. By following these steps for product, packer, and pump selection, you will be on the right path to a successful leak seal repair. 

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Mechanical packers and ports are used on almost every leak seal chemical injection project. If a contractor is using chemical grout, then there is a high chance that they are also using mechanical packers.  Considering that leak seal injections are often performed in small cracks and joints, the mechanical packer portion of the project is often more significant than the chemical grout. Let’s begin with a brief overview of packer terminology as reference.

Several suppliers offer 2-3 standard mechanical packers and ports assuming that these are generic in design and commoditized. This assumption is incorrect. Not all mechanical ports are created equal, and we aim to define these functional differences in this brochure.  Mechanical packers are most commonly defined by four key aspects; and these are Diameter, Length, Type, and Ball-Valve Location.

Let's examine the functional differences of these key aspects. 

Diameter: Mechanical packer diameter is relevant for two reasons, 1) this dictates the size of the drill hole required, and 2) the overall surface area of the rubber in the drill hole is a key contributor to the pressure tolerance of a mechanical packer. 

1. Size of drill hole considerations: Industry standards require 45-degree drilling to insert mechanical packers to a crack depth that is ½ the thickness of substrate.For thin substrates, for example 6” thick slabs, drilling at a 45-degree angle with a 5/8” drill bit may cause spalling and damage to the surface above the drilled angle as the outward heave force from the passage of the drill is greater than the strength of the concrete at that location, resulting in concrete spall and cracking damage at that location. For these applications, Alchemy-Spetec offers 5/16” (8mm) and 3/8” (10mm) diameter packers. The smaller cross section of drilling produces much less heave force against the face of the concrete and offers much better results when drilling into a thin concrete substrate. Post-tension structures and/or structures with a significant amount of rebar also present an obstacle when drilling. By reducing the size of the drill bit by 40-50%, the contractor also decreases the probability of drilling into rebar or post-tensioning accordingly.
   
   
2. The tradeoff for smaller diameter is a decrease in pressure tolerances. Common ½” (13mm) or 5/8” (16mm) mechanical packers tolerate spikes in pressure greater than 4,000psi. At 4,000psi, packers and ports can present a significant job-site hazard as they can exit the drill hole at dangerous velocities. While injecting at these pressures are never recommended, a ½” (13mm) or 5/8” (16mm) rubber base on the mechanical packer will prevent blow-out significantly better than the 5/16” (8mm) or 3/8” (10mm) counterpart. 

Length: Mechanical packers are most commonly used in poured concrete substrates. In adequately consolidated poured concrete structures, the drill hole itself acts as a channel through which the chemical grout will travel as it reaches the cross-section of the crack or joint. In these conditions, only the entire rubber shaft of the mechanical must be recessed into the drill hole to create an adequate compression seal. In the example of a 3” long packer, this would leave approximately 1.5” of metal shaft for connection access from the coupler that connects the hose line to the mechanical packer. However, it is common to experience micro-spalling at the point of drilling as the drill catches the 45-degree drill line. In these cases, the packer must be set even further into the concrete to ensure the rubber is fully recessed into the drill hole. This condition decreases the length of shaft accessible at the face of the substrate for connection to the coupler and can present challenges for the applicator. For this reason, it is advised to utilize 4” or 6” long packers in deteriorated or defective concrete substrates.

Length can also be advantageous when the contractor is attempting to inject the material to a specific point within the substrate. For example, it may be desirable to deliver chemical grout to the backside of a 4” substrate, or to a certain depth for a pipe penetration, or to account or unknown consolidation of the concrete within the drill hole channel that could lead to lateral travel of chemical grout to undesired locations within the substrate. Each job-site and substrate condition is different, and length of mechanical packer can provide the contractor with more options and ultimately a more effective delivery of chemical grout.

Type: Mechanical packers come in many types. In the concrete repair industry, contractors will find plastic, steel, brass, aluminum, zinc, and other metal alloys. The most commonly used type is steel. Steel offers the benefits of strength and resistance to oxidation through chemical grout oxidizing components found in grouts such as acrylics.  Brass and aluminum packers are weaker and allow for the shaft to be broken off by hammer for more timely patching efforts following injection. However, most Quality Control Managers and clients will require the removal of all metal from the substrate prior to patching. The chosen method of removal is the choice of the client and/or design professionals.

There are two types of plastic packers used. The 5/8” (16mm) button top packer is used for high volume applications and for applications in which a button-top coupler is preferred to minimize leakage. The free-floating ball in the middle of the packer acts as an anti-return valve. A 5/8” (16mm) plastic sleeve is inserted first, with the threaded plastic base then screwed into compression via the hex head top. Another common port used is the 3/8” (10mm) plastic bang-in, or hammer-in port. These ports are simply inserted into a 3/8” (10mm) drill hole aided by the force of a hammer. The soft nature of the plastic allows the concrete to bite into the sides of the packer creating a compression seal. Because plastic packer compression is achieved though plastic to concrete friction, the overall pressure tolerances are typically lower than that of the mechanical packer counterpart.

Aluminum packers have recently become more prevalent in the industry due to the combination of economical pricing with the benefits of mechanical packer pressure tolerances. Due to the softness of the components, however, these packers have been known to strip threads at times. All functionality considered, aluminum packers do offer a reasonably price alternative to the steel mechanical packers.

Alchemy-Spetec continues to offer a popular heavy-duty ½” (13mm) and 5/8” (16mm) packer with a soft grade of rubber and washer on the top of the packer that adds extra friction and bite to the concrete when tightened. The heavy-duty packer offering is in steel. These heavy-duty packers are top-mounted ball-valve style and can be converted to button-top valve (see next section and below).

Ball-Valve Location: Perhaps the most misunderstood functionality of mechanical packer design is the ball-valve placement. The ball-valve placement is important because this is the functional element that keeps chemical grout in the substrate as it reacts and creates the density required to adequately seal the substrate. It is an applicator error to remove the packers prior to full product cure. Top-mounted zerk-valve packers allow for port-to-port travel observation. Port-to-port travel is injecting one packer until chemical grout is observed exiting the next packer which does not have an anti-return zerk-valve installed. Once the material is observed coming out of the next packer, the zerk-valve can be installed, and the process repeated. This is only possible with top-mounted ball-valve placement. Another benefit of the top-mount packer is the ability to replace the standard zerk-valve with a button-top-valve. Button top valves, as mentioned above, minimize leakage with a more secure connection to the packer that doesn’t allow the coupler/packer connection to flex.

Bottom-mount ball-valves are less common in the industry. The main benefit of bottom-mount ball-valves is the immediate removal of the top shaft following injection, and subsequent patching of the drill hole with the ball-valve still in the substrate. Bottom-mount ball-valve packers commonly have a bit more leakage and excess chemical grout as the shaft, above the ball-valve, is full of unreacted and unconfined chemical grout.

Alchemy-Spetec supplies a complete offering covering all of the functionalities detailed in this brochure. All top-mount options can be converted to button-top style with by adding the equal quantity of Button-Top Fittings, ACP-2203.

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The most critical step of building a leak seal methodology is choosing the correct product. In our industry, there are products with varying degrees of flexibility, viscosity (thickness), expansion rate, type, and reaction time.  If the wrong product is chosen, the best equipment in the world won’t provide a successful, long-lasting repair.

Flexibility is very important in product choice as substrates that experience thermal expansion and contraction or dynamic loading causing movement, will require a flexible grade chemical grout (AP Seal 500, Spetec PUR F400) to remain sealed during movement. For curtain wall grouting or in joints and cracks that do not experience much movement, more rigid products (Spetec PUR H100, Spetec PUR HighFoamer, AP Fill 700) with higher expansion rates can get the job done. While flexible products do not offer the amount of compressive strength as their more rigid counterparts, the flexible functionality serves dynamic crack leak seal injection well.

Hairline cracks and cold joints require relatively thin (low viscosity) materials to penetrate adequately. Acrylic products offer the thinnest options (Spetec AG100 and Spetec AG200), while most of the Alchemy-Spetec single part polyurethanes also offer thin enough material to penetrate most concrete cracks and joints (Spetec PUR H100 and Spetec PUR F400). A common mistake, however, is choosing a product that is too thick resulting in excessive pressures and blow-outs. A common warning sign during injection is when pressures are continuously high, while very little chemical grout travel is observed. 

Most single part, catalyzed, water-reactive polyurethane grouts are expansive in nature. The amount of expansion typically varies from approximately 5-40x original mixed volume. The amount of expansion is important in many applications as it will be a factor in the total amount of material used, overall cell structure, and capacity to cut-off active water leaks. Spetec PUR HighFoamer can achieve an expansion rate of 50x. This is particularly beneficial when cutting off high-volume leaks and/or when performing curtain grouting. Expansion can create a significant amount of pressure behind a structure, so it is always advised to consider this behavior when injecting into a completely confined substrate.

Most leak seal chemical grouts are polyurethane-based, and hydrophilic or hydrophobic in type. Hydrophobic polyurethanes require water to initiate but are completely insensitive to moisture post-cure. These products are ideal for freeze/thaw and wet/dry cycles. Hydrophilic polyurethanes will expand and contract based on the amount of water in their environment. These products are ideal for applications in which there is constant water contact to keep them in their gel state. Hydrophobic polyurethanes include Spetec PUR H100, Spetec PUR F400, Spetec PUR F1000, Spetec PUR HighFoamer, and AP Fill 700. Hydrophilic polyurethanes include Spetec PUR GT350, AP Seal 500, and the acrylic grouts Spetec AG100 and Spetec AG200.

Reaction time plays a crucial role in the overall injection process as it will determine how fast the product will cut off water and also how far the product will travel. Most hydrophobic polyurethanes offer a catalyst component that can be used to control this speed. Depending on severity of leak, and thickness of structure, the catalyst can be adjusted accordingly to ensure that the product reacts when and where it is designed. Most polyurethane hydrophilic grouts do not offer catalyst components. Acrylic hydrophilic reaction times can be adjusted by adjusting the sodium persulfate concentrations on the B-side of the mix. The TEA component on the A side can also be adjusted, but for user-friendliness and simplicity’s sake, it is recommended to only adjust the sodium persulfate component.

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AP Lift foams have an inverse relationship between expansion and strength. The more they expand, the less compressive strength they have. The less they expand, the more compressive strength they have.

AP Lift 420 has the highest expansion which means it is the most economical product in terms of filling a void. It also has the lowest compressive strength.

AP Lift 475 expands less than half the amount of AP Lift 420, but the compressive strength is 370% stronger.

Understand that these expansion rates and compressive strengths are based on free rise foam. Free rise means that the material is allowed to expand with no resistance (example: foam that was mixed and expanded in an open cup). In most cases you are injecting these products into soil or into a void that is closed off on most sides. The foam meets resistance as it expands. The resistance reduces the amount of expansion and therefore increases the compressive strength. How much expansion is reduced varies from job to job and is influenced by soil conditions, void size and shape, quantity of material injected, etc.

Although each product can be used in multiple applications, here is a quick guide to product selection:

AP Fill 420 – Filling large voids, Deep Lift process
AP Lift 430 – Residential slab lift applications
AP Lift 440 – Highway concrete slab lift applications
AP Lift 475 – Heavy duty slab lift applications

Note: All of these products are designed to work in wet environments.

Want more information on lifting slabs with polyurethane?