Alchatek Blog

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.

Want more information on building a leak seal methodology?

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?

Spanning the Pithlachascotee River in New Port Richey, Florida is the Madison Street Bridge. Built in 1985, this structure was buttressed with four semi-circular seawalls at the base of each footing in the year 2000.

Over the years, tide fluctuation caused soils to wash out from underneath the seawalls. This caused the heavily used sidewalks on top of the walls to crack and settle, allowing even rainwater in. Without an alternate way for pedestrians to traverse the bridge, this structural problem quickly became a critical public safety issue.

Powerful Polymer

To rapidly address the problem a certified contractor relied on AP Fill 700 and its NSF 61-5 certification (approved for contact with drinking water). The rapid expansive properties of this semi-rigid hydrophobic resin made it the optimal solution for painlessly filling the voids that had developed in the seawall and stopping the erosion beneath the sidewalks.

Painless Procedure

To rapidly address the problem a certified contractor relied on AP Fill 700 and its NSF 61-5 certification (approved for contact with drinking water). The rapid expansive properties of this semi-rigid hydrophobic resin made it the optimal solution for painlessly filling the voids that had developed in the seawall and stopping the erosion beneath the sidewalks.

Rapid Result

Stopping the leaks in all four seawalls only took a few days. More than a year later the seawalls are still as good as new.

Want in-depth info on polyurethane seawall repair?

The Problem

As tidal flows rise and fall, water pushes its way in through cracks, joints, and defects in seawalls.  The water pushes in on incoming tides and flows out on outgoing tides.  As the water flows out, it carries sand and soil with it which causes undermining of the structure, voids to form, and deteriorates the structural integrity of the seawall.  This cycle is exacerbated during periods of heavy rain which continue the outflow of soil.

The Solution

AP Fill 700 is a semi-rigid hydrophobic polyurethane foam that reacts with water or moisture in the soil and expands to fill voids while it permeates sandy soil to form a solid, strong, watertight mass.  It has been used extensively in seawall applications to seal cracks, voids and defects as well as for filling voids and stabilizing the soil.

The Process

AP Fill 700 can be injected through pipes directly into voids and loose sandy soil using a single component pump (airless sprayer or double diaphragm pump).

Step 1:  Insert pipes down to the lowest level to be injected.  This can be done through driving the pipes mechanically, water jetting, or air jetting them down.

Step 2:  Ensure the soil has enough moisture content to cause a reaction of the AP Fill 700 (slightly damp to saturated).

Step 3:  Blend catalyst with AP Fill 700 to desired level.  Typically, between 2% and 5% AP 106 Catalyst will be sufficient.

Step 4:  Connect the hose from the pump to the injection pipe.  The hose should have a ball valve to control the flow of the material.

Step 5:  Inject AP Fill 700 either at a pre-determined rate (rule of thumb is 1 gallon per vertical foot) or until sufficient back pressure is established.

Step 6:  After each “point” is injected, raise the pipe 12” and repeat the process.  Once the pipe is within 24” of the surface you will probably get material flowing back to the surface (known as “refusal”).  Stop at this point and move to the next pipe.

Step 7:  Repeat this process until the entire area has been injected.

Note:  A containment barrier should be used on the water side of the seawall to capture any foam that leaks out of the seawall during the process.

Note:  Check valve type drains may need to be installed in the seawall after injection to allow water from heavy rains to vent out and reduce pressure on the seawall.  These drains will allow water to flow out, but not soil.

Want in-depth info on seawall repair procedures and products?

Repair sea walls instead of replacing them by stopping high flow leaks, filling the voids behind concrete structures and binding loose soil with:

AP Fill 720 & AP Fill 700 — innovative, cost effective, water activated, low viscosity, simple to use closed cell polyurethane injection resins.

Proven Strength

• Because these foams are impermeable to water once in place, the likelihood of future erosion is vastly diminished versus other commonly used fill materials.
  
  
• Originally developed over 30 years ago, and continuously improved since, this technology has one of the longest histories of success in the field among engineering uses of polyurethane foams.

Environmentally Friendly

• Phthalate free.
• Approved for contact with drinking water.

Quick Set Time vs Cement Grout

• AP Fill 700 & 720 foams set in 10 minutes or less.
• Cement grout takes hours to days.

Differences Between 700 and 720

• 720 has a higher expansion ratio and is more flexible when cured.
• 700 has a lower viscosity, so it works better in cooler temperatures.

Want a complete technical breakdown of AP Fill 700 & 720 for seawall repair?

When it comes to seawalls, there is a lot more to learn than meets the eye. A seawall is like a living, breathing thing: especially in the way that it is designed to function. But like all living breathing things, they have a finite lifespan. For many of them, it's a mere 20 – 30 years. Depending on where you live, replacing a seawall can cost anywhere from $150 to $500 per foot. That's enough for some homeowners to choose to move instead of rebuilding their seawalls. Today however, signs of seawall distress can be solved before they get too bad through the application of polyurethane grouts to seal leaks, fill voids, and stabilize the surrounding soils.

Although seawalls are found around lakes and rivers, it is around the ocean that they are put to the most difficult test. Salt corrosion, tidal action, currents, boat wakes, storm surges and sometimes hurricanes all deliver a constant beating on the seawall. But many of the forces are also coming from the landward side of the wall. Every time it rains or the irrigation system runs, and every time the tide goes out; all of the groundwater above the waterline has to vent or equalize. Tremendous pressures can build up if that water is trapped and cannot make its way into the sea or the storm water system.

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. 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.

When signs of sinking ground are observed, you can almost be sure there are voids below that are unseen and dangerous. Sometimes these voids can extend below an adjacent patio, dock, or pool deck, causing those to sink and crack. Anticipating those problems is key to keeping those problems at bay, and proper application of polyurethane injection is the solution. AP Fill 700 is a lightweight injection resin that can be injected along the wall where the settling is occurring and generate multiple benefits. It will seal any leaks along the wall, fill the voids that have occurred, and mix with the soil to form a solid, impermeable mass. Combined with proper drainage, this method can extend the life of your seawall.

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. Advanced polyurethane technology from Alchemy-Spetec is a key to extending the life of your seawall. It's fast, clean, easy to install, and most of all, effective.

Want in-depth info on seawall repair procedures and products?

I met with a contractor today who does residential slab lifting and for some reason we ended up talking about incoming leads and how to prequalify them. Every slab lifting or foundation contractor has experienced driving for hours to look at a potential job that turns out to be a wasted trip. Every property owner has probably taken time off from work to meet a contractor who wasn't the right fit either. It's not anyone's fault but it can be avoided, saving both the contractor and the property owner valuable time.

I thought it might make a good blog topic: how to technically evaluate an incoming lead before sending a salesperson out to do a site evaluation and estimate.

Here are some prequalifying questions to consider asking a property owner:

1. Can you text me or email me a picture of the sunken slab, stairs, pool deck, etc?
   This will tell you a lot because pictures may reveal that the concrete is too fractured for lifting. If so, you'll save yourself a trip. You may also notice some impediments to the lifting process, like brickwork or bound slabs. Pictures may also reveal the cause of the problem, like erosion caused by poorly directed roof drains. With this info you can start developing a plan right away (if you decide on a site evaluation).
   
   
2. How long has this been going on?
   It's important to ask the owner how long the settling has been going on. If it is recent and happening at an accelerated rate, that may indicate an entirely different problem than a slab that has settled over a period of years. Settling related to erosion and compaction issues, as well as buried organic material, usually occurs gradually. Broken pipes and sinkholes, on the other hand, usually cause rapid sinking and need attention immediately. It might be better in these cases to recommend a plumber or geotechnical engineer first before going to look at the sunken slab.
   
   
3. What information is available?
   Has anyone else been out to look at it, what were their findings, and are there any available engineering reports? This is pretty self-explanatory. Information is extremely helpful on geotechnical jobs whether it is data from ground penetrating radar, soil borings, penetrometers (DCP), etc. Even local knowledge of the property can be very helpful. Were any new buried utilities put in, or were there any adjacent property developments where de-watering was incorporated? This information may also keep a contractor from making a mistake by quoting on something they are possibly not qualified to execute. As Clint Eastwood (I wish) once said, "Slab lifting contractors must know their limitations".
   
   
4. Is this property for sale or going on the market?
   This is a sensitive subject to write about because some of our contractors do get leads from real estate experts and property owners. Often there has been an inspection and the report indicates a tripping hazard or a settling issue. The owner and potential buyer will use the repair estimate to negotiate on the sale price and no work ever gets done. It's fair to ask if this is just a quote required for the sale of the property or if there is a real intention of fixing the issue.
   
   
5. How far down is the slab or foundation?
   It takes a certain amount of polyurethane to lift a slab. Sometimes you have to accept that a slab that is down 12 inches may be more affordably replaced than lifted. However, sometimes a slab that's down several inches may be in a location where demolishing it and bringing in new concrete is disruptive. The polyurethane may be the best and only answer; one of the things that makes it great.
   
   
6. Are you the owner?
   I can appreciate a renter's concern about concrete settling but you obviously need to talk to the owner. There have been many site visits made on request of a renter to be used as a complaint against the owner. I'm not saying these are illegitimate issues but they deserve to be evaluated carefully.

In addition to asking the questions above, you'll want to keep these two points firmly in mind:

1. Stay focused on the repair.
   In the concrete repair, soil stabilization, and slab lifting business, contractors are often called in when something is going wrong. Something is leaking, sinking, cracking, etc. When evaluating a job site it is always a good idea to consider what you say and what you propose to the client. It is good policy to focus on the repair rather than give your opinion on why something happened or why the engineer recommended a repair method. That is context sensitive obviously, but sometimes there are litigation issues that could be pending.
   
   
2. Make sure they know you're using polyurethane rather than cement grout.
   Last of all it's always a good idea to make sure the client understands you are using polymer technology and that you are not a mudjacking outfit. Polyurethane slab lifting with the AP Lift series of foams is cleaner, permanent, it doesn't shrink or wash out - and our certified contractors are better looking, ha ha.

Want more information on polyurethane slab lifting?

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 (see FIGURE 7).  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 (see FIGURE 8).  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 (see FIGURE 9).

Bottom-mount ball-valves (as seen below FIGURE 10) 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.  Below is a table detailing bottom-mount options and top-mount options.  Note: All top-mount options can be converted to button-top style with by adding the equal quantity of Button-Top Fittings, ACP-2203.

Want more information on mechanical packers? 

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 (see FIGURE 4). 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 through 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 (see FIGURE 5). 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 (see FIGURE 6). These heavy-duty packers are top-mounted ball-valve style and can be converted to button-top valve (see next section and below).

Want more information on mechanical packers?

Due to a driver shortage in the shipping industry, non-guaranteed
shipments are being pushed to the back of the line, re-routed, or
even placed on rail.

When you choose guaranteed service, we have much more leverage
in the event delays do occur.

We now recommend choosing guaranteed service if your order is
time sensitive and ordering at least a week in advance when possible.

Click here to view a USA Today article on the current driver shortage
in the shipping industry.