Alchatek Blog

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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Unstable soil can be defined as soil that will not stay in place on its own, and therefore requires extra support. It should be noted that unstable soil can threaten the stability, security, and safety of infrastructure and can damage, degrade, and even destroy a number of structures, such as buildings, bridges, and roads. There are a variety of factors that can cause unstable soil including erosion, poor compaction, freeze/thaw cycles, and decomposition.

The Causes of Unstable Soil

Erosion
Poor drainage, improperly placed downspouts, leaking drain pipes, and broken water lines are common culprits.

Poor Compaction
When backfilling on a job site, the contractor is supposed to compact the backfill by driving over it with heavy equipment. However, this isn’t always done properly for one reason or another.

Freeze/Thaw
Processes of freezing and thawing essentially accelerate erosion processes. Cold weather freezes moisture trapped in tiny cracks. When this water freezes, it expands, subsequently pushing on the rocks and breaking them into smaller pieces. As processes of freezing and thawing continue, rock and sediment are continually broken down.

Biological Decay
Construction trash pits, buried trees, and other biodegradable materials all break down. Sometimes structures are built over these areas.

Stabilize Soil with Polyurethane

Loose soil can be consolidated, voids can be filled, and water migration halted by permeating the soil with one of the AP series products of ultra-low viscosity polyurethane resins. Once the bearing capacity of the soil has been increased with this process, then the structure can be lifted if necessary.  Learn more about Soil Stabilization Products here.

Want more information on polyurethane soil stabilization?

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.

Want more info on crack injection and curtain wall grouting products?

Looking for polyurethane concrete repair product Tech Data Sheets, Safety Data Sheets, Application Procedures, Case Studies, Environmental Safety Info, or Specifications?  All of these documents are available on one convenient page at Alchemy-Spetec's Comprehensive Download Resource Center.

Technical Data Sheets for Polyurethane Concrete Repair Products

Technical Data Sheets are available for the following product categories:

• Leak Seal
• Soil Stabilization
• Slab Lifting
• Water Stop
• Structural Repair

Safety Data Sheets for Polyurethane Concrete Repair Products

Safety Data Sheets are available for the following product categories:

• Sealing Leaks
• Stabilizing Soil
• Lifting Slabs
• Structural Repair
• Accessories

Procedures for Polyurethane Concrete Repair Applications

Procedures are available for the following applications:

• Standard Application for Injecting Cracks and Joints
• Railroad Ballast Rock Repair and Stabilization
• Manhole Infiltration Control
• Concrete Pipe and Corrugated Metal Pipe Joint Repair
• Targeting Pipe Leaks with Point Grouting

Case Studies for Polyurethane Concrete Repair Projects

The following Case Studies are available:

• Contractor Successfully Completes Unique & Challenging Driveway Lift
• Deep Soil Stabilization with Polyurethane
• Protecting a Building Foundation Next to an Excavation Site
• Stabilizing a Foundation to Save a Valuable Two Story House
• Protecting Drinking Water from Potential Flood Contamination
• Leaks in Wastewater Treatment Plant Sealed to Prevent Environmental Contamination
• Sealing Leaks in a Church Wall to Stop Costly Flooding of Elevator Pit
• Leak Seal at Water Treatment Plant
• Leveling Sunken Slabs in a Pole Barn
• Massive Underground Leak in Aquifer Shut Down
• Sealing Hairline Concrete Cracks with Acrylic Injection Resin
• Seawall Repair at Base of Bridge
• Slab Lift for Chinese Railway
• Slab Lift at Seed Sorting Plant
• Soil Stabilization at Busy Intersection

Environmental Safety Info on Polyurethane Concrete Repair Products

NSF Certificates are available for the following products that have been approved for contact with drinking water:

• AP Lift 430
• AP Lift 475
• AP Soil 600
• AP Fill 700
• AP Fill 720
• Spetec PUR F400
• Spetec PUR GT500
• Spetec PUR HighFoamer
• Spetec PUR H100
• Spetec PUR H200
• Spetec AG200

Engineering Specifications for Concrete Repair with Polyurethane

The following Engineering Specifications are available:

• Injection Grouting – Hydrophilic
• Injection Grouting – Hydrophilic & Hydrophobic
• Slab Lifting with AP Lift 430
• Permeation Grouting

Want more info on polyurethane concrete repair products?

A homeowner called Home Energy Professionals in Tennessee with an interesting driveway problem. There was an 8-inch drop at the point where the driveway met the edge of the garage floor. That was enough to prevent the resident from getting their car into the garage at all. The homebuilders did not extend a nearby gutter downspout far enough away from the driveway. Rainwater caused erosion under the slabs, causing them to sink over time. What made this case unique was the fact that the final slab (closest to the garage) in this 20-foot-wide driveway was only two feet long. Slabs with such narrow dimensions are notoriously difficult to lift evenly. Due to the unusual nature of this job, they called in Alchemy-Spetec’s Colt Hullander (Director of Technical Services – Geotech Division) as a consultant.

Powerful Polymers

The Home Energy Professionals crew used AP Lift 430, a two-component, high strength, high density, hydro-insensitive structural polyurethane foam. They chose AP Lift 430 because it’s one of the most consistently reliable lifting foams in the industry. This high-density foam is extremely strong, providing concrete slabs and structures with reliable and lasting support.

Painless Procedures

The crew drilled their first injection hole about 3 feet from one edge of the slab, right in the middle of the 2-foot length (about 1 foot in from both edges). They lifted this end of the slab for about 2 inches and then stopped. Lifting any further at this point would likely have cracked the slab. Next, they drilled another hole about 6 feet in from the edge and repeated the process. When they reached the end of the 20 feet, they started again – redrilling that first hole and lifting another 2 inches. With this gradual injection process, they carefully raised the slab 8 inches and leveled it off with the garage floor. They then moved on to lift the other, conventionally sized slabs in the rest of the driveway.

Rapid Results

This challenging slab lift job was completed in just 3 hours. Fifteen minutes after the injections were completed, the homeowner was able to drive their car across the newly leveled driveway and into the garage. The crew at Home Energy Professionals had another successful job in the books!

Want more information on lifting slabs?

A general contracting company working on an excavation job for a new sea turtle habitat at Loggerhead Marinelife Center in Juno Beach, Florida needed specialists to protect the foundation of the adjacent building from potential destabilization. Underground Services of America was called in to create a polyurethane grout wall for this very purpose.

Powerful Polymer

The crew used AP Soil 600, a single component, moisture activated, hydrophobic, extra-low viscosity, polyurethane soil grout. This is the premier product for stabilizing soil via permeation grouting. It's also NSF-approved for contact with drinking water. Using an environmentally safe repair material in a marine habitat is extremely important.

Painless Procedure

Underground Services of America professionals drove injection rods into the ground next to the building foundation in a staggered pattern (see photo). The rods were 18 inches apart from each other to ensure consistent, thorough permeation of the soil with the high-strength grout. They injected at a rate of one gallon per foot. A total of 500 gallons was used to form the grout wall. The project was completed in just two days.

Rapid Result

The resin was cured within 24 hours of completion. The job was finished on a Friday. On the following Monday, the GC began excavation on the future sea turtle habitat without any fear of damaging the adjacent foundation.

Want more information on soil stabilization products and procedures?

A couple of recent judgments in slip and fall cases should concern any property owner with slip OR trip risks on the premises. 

On July 12, 2019, WTXL TV in Tallahassee posted an article on their website about a near 2 million dollar judgment for a slip and fall case at a local convenience store:

On Thursday, a Leon County jury ruled that Siraji Inc., the owner of the USA Grocers convenience store in the 2600 block of Roberts Avenue, was responsible for causing the 2016 slip and fall of 47-year-old Stephanie Jenkins. Jenkins was awarded $1.9 million for the permanent and severe injuries she sustained.

On January 8, 2021, Daily Report posted an article about a 1 million dollar judgment in an Atlanta slip and fall case:

Nearly a year after a judge awarded a woman injured in a slip-and-fall accident at an Atlanta restaurant more than $1.1 million in damages, the parties have settled for just over $1 million.

These are record judgments against property owners for these types of accidents. If you have a trip and fall litigation risk on your site, contact us for a qualified slab lifting contractor referral today!

Want more information on leveling concrete slabs?

Planners at Washington D.C.’s water utility, D.C. Water, decided to take proactive measures against potential flooding of their facility. Located right next to the Potomac, their facility could’ve been at risk in the event of an out-of-the-ordinary natural disaster. Determining that the main risk to the water supply in such a case would be permeation through sub-surface soil, they began installing a metal sheet pile wall deep into the substrate between the riverbank and the facility. However, in some spots they were not able to drive a sheet pile panel into the ground because of underground utility lines or rocky substrate. The planners called in LJS Waterproofing to create sub-surface grout walls in those spots to fill in the gaps.

Powerful Polymer

The LJS crew “constructed” these sections of the underground wall by injecting AP Fill 700. This is a single component, water-activated, hydrophobic, low viscosity, closed-cell polyurethane injection resin. This grout was used because it permeates the soil, fills small voids in the soil, and cuts off water flow.

Painless Procedure

LJS professionals used a Geoprobe to drive injection pipes into the ground (up to 33 feet in some locations). They then injected one gallon per foot using upward staging. The next injection point was 18 inches away from the first one. This process was repeated until a grout wall formed, filling the gap between the two adjacent underground sheet piles. For a large-scale job like this, LJS used the PolyShark single component grout pump.

Rapid Results

With solid, impermeable grout walls filling in the gaps, a sub-surface barrier between the riverbank and the drinking water facility was now in place. The planners at D.C. Water were very satisfied with this solution. LJS Waterproofing came through exactly in the way they had promised.

Want more information on Alchemy-Spetec products?

The administrators of a church in Kingston, New York discovered water leaking through a wall into a hallway. The leak was located right next to the elevator. As water seeped into the elevator pit, it became flooded. Elevator pits often contain oil from hydraulic leaks in the equipment. Disposing of that oily water over and over can cost a property owner tens of thousands of dollars over time. The administrators reached out to LJS Waterproofing for assistance before the problem drove their budget through the roof.

Powerful Polymer

The LJS crew injected Spetec PUR F400 polyurethane grout to stop the water infiltration. This material reacts with the water inside the concrete cracks, curing to form an impenetrable seal. Chemical grouts are the most reliable way to shut down leaks in concrete.

Painless Procedure

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

For a complete overview of the crack injection process LJS professionals used on this job, see the Alchemy-Spetec blog post series 5 Steps of Concrete Crack Injection.

Rapid Result

The crew finished the repairs in a timely manner, saving the church a great deal of money in the process. The hallway is now completely dry and the elevator pit is no longer flooding. An ounce of prevention, in this case, was definitely worth a pound of cure!

Want more information on Alchemy-Spetec leak seal products?

The owners of a valuable one-story house in New Jersey decided to add a second story to the structure. Unbeknownst to them (and to the contractor who worked on the project) four feet of the soil beneath the foundation had been poorly compacted by the home builder. When the second story was added, the soil could not support it and the foundation was critically damaged. The foundation issue caused the structure to shift a bit, which then caused roof damage as well.

When the contractor attempted to replace the roof, rainwater infiltrated the structure, eventually reaching the poorly compacted soil beneath the foundation and creating voids. These voids further destabilized the entire structure. Talk about a problem going from bad to worse! By this point, the residents had been forced out of their home for about a year! The general contractor then contacted LJS Waterproofing for assistance. A contractor in New Jersey with extensive soil and foundation stabilization experience, LJS quickly arrived on the scene and took immediate action to remedy the situation.

Powerful Polymer

The LJS crew used Alchemy-Spetec’s AP Fill 700 high-strength soil stabilization grout to solidify the four feet of poorly compacted soil beneath the foundation. This polyurethane resin was the ideal choice because of its ability to thoroughly permeate the soil and then cure to an incredibly high compressive strength. LJS used Alchemy-Spetec’s PolyShark grout pump to install the material. This pump is specifically designed for large-scale soil stabilization jobs.

Painless Procedure

The crew used a Geoprobe pipe driver to insert grout injection pipes four feet deep into the supporting soil around the house. AP Fill 700 was then injected to stabilize the soil. They also used a carbide drill bit to create small 3/8” drill holes in the concrete foundation slab in a diamond pattern, 4 feet on center. After each drill hole was created, the crew inserted a pipe through the slab and into the ground, pumping the grout to stabilize the soil and fill the voids.

Rapid Result

LJS completed stabilization of the entire foundation in just two weeks, ending a year-long cycle of compounding problems for the structure. This allowed the general contractor to repair the foundation, finish replacing the roof, and replace the damaged flooring with no further issues. Most importantly, the beleaguered residents were soon able to move back into their house after an exhausting, year-long ordeal.

Want more info on Alchemy-Spetec geotech products?