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).

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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.

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 (see FIGURE 3). 

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.

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 (see FIGURE 1).  

   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 (see FIGURE 2).  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.

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. Over the next few blog posts, we’ll examine the functional differences of these key aspects.

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The North American Tunneling Conference (NAT) is the premier tunneling event for North America, bringing together the brightest, most resourceful and innovative minds in the tunneling and underground construction industry.

Here are 5 reasons to visit Alchemy-Spetec at NAT 2018:

1. LEARN more about our Leak Seal and Geotechnical chemical grouting product offerings. 
2. DISCUSS our comprehensive chemical grout training school coming in September.
3. EDUCATE yourself on our injectable and hydrophilic polymer waterstop systems for precast segments and walls.
4. SCHEDULE one of our experienced field technicians for a site visit.
5. PLAY with expanding foams and gels to get a sense of how these products work.  

• Monday June 25th:  5pm - 7pm (Opening Reception)
• Tuesday June 26th:  11am - 2pm, 4pm - 6pm
• Wednesday June 27th:  9am - 12 Noon.

Alchemy-Spetec will be in booth #659 in the floorplan linked below: 

NAT 2018 Interactive Floorplan

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Slab Jacking with Lighter Material Prevents Further Sinking

We are often asked about the biggest advantages of lifting settled concrete slabs with polyurethane foam vs. cement grout.  One of the biggest advantages is the weight.  Depending on the product, the density of structural polyurethane lifting foam is between 3 ½ and 5 pounds per cubic foot.  The same volume of cement grout weighs 140 pounds per cubic foot. This translates to 30 to 40 times more added weight using cement vs. polyurethane. By using lighter weight materials, you are giving yourself a much greater chance for long term success.  (Polyurethane is strong enough to support any structure, as explained in our earlier blog post How Strong is Strong Enough.)

Concrete Lifting with Polyurethane Creates Less Mess

Another advantage of using foam is the size of the drill holes.  Drilling holes for foam is quick and easy, requiring only a 3/8” hole to inject through.  For mud jacking you are drilling injection holes ranging from one to two and a half inches.  This takes longer, does more damage to the concrete, and the drills and drill bits are more expensive.  With mud jacking there are the additional problems of messier works sites and disposal of unused mixed cement.

Mudjacking with Cement Requires Longer Cure Times

The final advantage of foam over cement is time.  All of our AP Lift series products reach 90 percent of their final strength in 15 minutes and are fully cured in less than a day.  Literally, as soon as you are done packing up your equipment the foam under the slab is ready for traffic.  On the other hand, cement grout can take days to reach final cure.  Having immediate load bearing traffic is especially important for facilities such as warehouses that run 24/7 and need to use the lifted area as soon as the job is complete.  

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Aim for Opportunity

In this article, we'll identify opportunities and markets where slab jacking is needed. Three main markets we will take a look at are Residential, Commercial / Industrial, and Transportation.

Residential Slab Jacking

The residential market offers tremendous opportunities for the slab lifting contractor. Obviously, there are driveways and foundations. These can all sink for various reasons such as water runoff, excess weight, and poor compaction. But look a little further; this year alone we have had calls concerning the following areas: patios, outbuildings, pools, and porches. And don't think residential only includes houses. I'm not officilally saying that construction companies building condos and apartments would bury trash that would later cause settling issues; I'm just saying....

Commercial / Industrial Slab Jacking

Because the scenarios for slab lifting are endless for non-residential slab lifting, I am going to lump Commercial and Industrial together. Concrete parking lots are often lifted now instead of replaced. The same goes for busy warehouse floors; lifted and back in business in hours, not days. Another place to look is slabs beneath equipment; they are not always originally designed to support heavy loads but the equipment ends up there anyways. Anywhere there is a transition there could be a lifting opportunity. From inside to outside, from slab to slab, from parking lot to parking deck, and any areas where there is water runoff.

Slab Jacking for the Transportation Sector

Last but not least, take a look in the transportation sector. Our highway and road building contractors do a great job. But in the miles and miles of asphalt and concrete, there are going to be some settling issues. Look again at transitions, from highway to bridge (the bridge approach slab) is a good example. Think airport taxiway slabs don't ever sink? Wrong. Think slabs under railroad tracks don't ever need stabilizing and leveling? Wrong again. And the advantage for lifting with polyurethane really shines in this sector. Strong, fast, and back in business in hours, not days.

So get off your assets and go lift something.

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Raising Concrete with Confidence

When pumping a light-weight material beneath a slab, you need the confidence that it is strong enough for the application. How strong is strong enough? This is a commonly asked question by contractors that are new to slab jacking with polyurethane. Alchemy-Spetec structural foams only need to be as strong as dirt, but they're actually stronger than crystalline bedrock.

The Right Strengths for Concrete Lifting

Slab lifting foams are rated on density (weight per cubic feet) and compressive strength. This testing and rating is based on the foam in a free rise state; the parts A and B are mixed together and allowed to expand freely. Our AP Lift 430 and AP Lift 475 structural lifting foams, for example, will weigh 2.75 – 3.25 lbs (AP Lift 430) to 4.75 – 5 lbs (AP Lift 475) per cubic foot. But they have a compressive strengths of 50 psi and 100 psi in a free rise state. That's equal to 7,200 to14,000 lbs per square ft of support, just in a free rise state.

Polyurethane Slab Jacking Compared to Clay and Bedrock

To put that into perspective, the National Home Builders Association and the International Building Code lists stiff clay at 4000 psf and crystalline bedrock as having 12000 psf of load bearing capacity. Consider the job site conditions where the foam will be injected into a confined area. Testing data in the lab shows that our lifting foams will increase in compressive strength: In a space confined 25% by volume there will be an increase of 31% in psi and in a space confined by 75% there will be a 79% increase in the psi.

Slab Jack for Any Job with the Right Foam

Today polyurethane lifting foams are used to level airport slabs supporting jumbo jets, equipment and building slabs supporting tremendous loads, and even railway sleepers that support the heaviest freight trains. So don't let the word “foam” fool you. These resins cure to strengths beyond what is needed to support any structure.

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You can lead a hose to water…

Waterstops are common and come in all different shapes and sizes. What if you could install one that was 100% custom fitted for your project? Well that is how the I.T.S. (Injectable Tube System) works. It allows injection of a cold joint or construction joint via a pre-installed injection canal/hose. This is normally done with a flexible polyurethane.

The end result is a custom shaped, flexible urethane “gasket” or waterstop. The grout will even fill in any honeycombing or defects and is considered a life-of-the-structure product.

The I.T.S. can be used as a stand alone waterstop, or it can be installed inside of a waterstop and injected as needed. Settlement of a structure can eventually lead to leaks, so it is great to have a pre-installed method to address those leaks when they appear.

But wait there's more! There is also an R-I.T.S. (Re-Injectable Tube System). The Re-Injectable Tube System is very similar but is for use with acrylate grouts instead of polyurethane. It is rubber based and has slits that act like valves. This allows for the pressurized grout to travel out into the substrate.  Then the tube can be flushed with low pressure water that does not open the “valves”.

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