Airport Runway Leveling in Azalea Park

How Runway Pavements Sink Within Azalea Park's Sandy Soil

Most people are unaware of what's happening within a runway until cracking surfaces or the slab has already dropped 0.5 inches. At that point, the subgrade has already settled. This Azalea Park, FL soil has a distinctive character.

Central Florida has sandy soil, organic material over bedrock. These materials are less stable. When it rains, the sand compacts unevenly and leaves a space beneath concrete slabs. Our team can repair settling foundation near Semoran Boulevard. Azalea Park, especially in the 32807 zip code near the Orlando Executive Airport, has a higher water table.

Common Runway Issues

Runway slab problems are almost always the result of one of these factors:

• Water table changes that weaken the soil over time
• Degradation of organic material underneath the slab, resulting in gaps and voids
• Inadequate compaction at time of construction leads to gradual subgrade settlement
• Heavy rain events wash fine sand away

Typically it's a mix of factors. The soil in this area drains quickly, but remains saturated for days after a storm. This creates an expansive soil environment that erodes the subgrade beneath.

Runway slabs have unique requirements when compared to a sidewalk or driveway. Runways are subjected to continuous loadings and repeated impact events. Voids grow quickly under repeated loads. A quarter-inch gap today becomes a two-inch settlement next season.

Florida bedrock is limestone, which is more at risk. Limestone bedrock may have natural dissolution channels, which can funnel groundwater under the slab. There have been many occasions where we saw good concrete on top, but voids several feet wide underneath. You cannot tell this by looking at the surface. It must be probed and detected properly. Early assessment of any settlement is very important. It doesn't get any better without action.

Airport Concrete Assessment and Signs You Need Leveling

Runway professionals typically call us when they've detected something. That's not unusual. The sooner you catch a runway settlement, the cheaper it will be to level.

We've been repairing airport concrete in Azalea Park, FL and surrounding region for many years. Signs of runway settlement are quite consistent. Keep these in mind when looking at your runway, taxiway or apron:

• Pooling water after rain. When the runway or taxiway has water sitting on it after the rain, the slab has probably settled unevenly. The frequency of storms we see here in Central Florida makes this happen very quickly.
• Visible cracking on joints or in the center of a slab. Hairline cracking will propagate when an aircraft travels over it more than once or twice. Wide cracks leave voids underneath the slab.
• Slab edges that are not even; a "lip" on transitions. This happens on the ground with aircraft and vehicles. Pilots notice this as well. A lip that is ½″ or more causes stress on aircraft and airport equipment during take-off and landing.
• FOD (Foreign Object Debris) issues because of spalling concrete. The spalling concrete surface creates FOD which is a safety hazard that any airport can not tolerate.
• Areas that appear soft or spongy at the edges of slabs or pavement. This is almost always the result of soil erosion below the concrete. This occurs with the sandy soils below most airport surfaces.

In most of these instances, the cause is exactly the same. Over time, Florida's sand and soil washes out, especially around the edges and where water pools or flows away from the slab. This causes the slab to lose support below and settle. A great example of this is on airport runways that are below and near Lake Underhill Road. In fact, the majority of the airport runways in the 32807 zip code have a high water table underneath the runway surfaces.

What is amazing, and often overlooked, is the fact that a runway can be perfectly smooth but has large voids underneath it. We have found three-inch voids below airport runways when lifting up the slab in the Azalea Park section. There is no way that anyone would know these voids are there just by walking along the runway. This is why you need a proper survey conducted before any maintenance is started.

If the maintenance staff continues to fix the same cracks on the runway, or if the operations crew continues to bring water problems to your attention, you have to look below the surface of the slab. These are the signs that you are about to experience runway settlement and slab failure.

Polyurethane Foam Injection: The Go-To Method for Airport Concrete Leveling

When you picture having your airport runway, taxiway or apron slab leveled, most people have an image of heavy-duty construction equipment and days, maybe even weeks, of airport closures and operational downtime. This was true until polyurethane foam injection for airport slab leveling came into the marketplace.

These days, polyurethane foam injection is our preferred choice for leveling airport runways in Azalea Park, FL. The reasons behind our preference for this method of slab leveling are listed below.

Polyurethane foam injection for concrete leveling consists of using a specialized two-part polyurethane material that is injected below a concrete slab that has settled. The polyurethane material is injected through very small injection holes that have been drilled into the concrete slab. These holes are the size of a penny. Once it is below the surface the material expands and lifts the concrete slab back up to the proper grade. The material hardens (cures) in around 15 minutes. This means that the concrete slab can be used (is ready for load-bearing) within 15 minutes.

Why Polyurethane Foam is the Preferred Concrete Lifting Method for Airport Runways

Mudjacking is a traditional concrete leveling technique that involves the injection of a heavy cement slurry under the concrete slab. Although this technique can be used successfully to lift and level sidewalks and roads, it is an inappropriate solution for airport runways. The cement slurry used for mudjacking is heavy. The weight of mudjacking material used for concrete lifting is around 100+ pounds per cubic foot. The weight of polyurethane foam used for lifting concrete slabs is around 2 to 4 pounds per cubic foot. Weight matters! The soil underneath many airport runways in the 32807 zip code (especially in low spots that can hold a lot of water) has trouble bearing loads., the weight of the polyurethane foam is perfect and will not damage the soil bearing capacity below the runway or pavement.

• Foam is waterproof and will not wash out even in Azalea Park's heaviest rainstorms.
• It fills voids completely since it is capable of expanding into any irregular space beneath slabs.
• Injection holes are so small that they do not impact the surface of the runway.
• Cured foam will never shrink, compress, or break down in the future.

Over the years, we have seen other methods utilized on a number of commercial slabs near the Semoran Boulevard airport. And those same businesses eventually call us back to complete the job the initial crew could not finish. Foam injection is more than just efficient; it's accurate. Our technicians utilize laser levels to measure the lifting process as it is occurring, which lets us fine-tune flow rates until we hit the right elevation to the smallest fraction of an inch.

The Federal Aviation Administration (FAA) stresses the significance of keeping the appropriate runway grade in place for safe aircraft operations and proper drainage of stormwater, which is just what polyurethane foam injection does. In addition, because we are not importing tons of heavy materials, we cause less interruption to the surrounding taxiways and aprons as work is performed.

Need some help determining if foam injection is right for your airfield project? Give us a call.

The Detailed Airport Runway Leveling Process

People ask us on a consistent basis what exactly goes into an airport runway leveling project. That is a fair question. It is nothing like a typical driveway repaving project. Each step in the leveling process has to be accounted for because aircraft are unable to handle uneven surfaces.

Here is the rundown of what happens when we work on the Azalea Park airport runway or other commercial slabs near Orlando Executive:

1. We survey and map the slab. Using laser guided profiling equipment to measure, we locate and measure every dip, void, and high point on the runway surface. This level of accuracy means measurements in a mere millimeter, providing detailed documentation of where the concrete has moved and by how much.
2. We drill injection ports. Small holes, usually just five-eighths of an inch in diameter, are drilled through the concrete at specific intervals. Based off of our survey, we determine where these holes are located; there is absolutely no guesswork. Every job has a unique pattern because slabs do not all settle in the same way.
3. We inject polyurethane foam. Using high density polyurethane foam, we inject the material through the ports. Foam first fills voids under the concrete, then provides the lifting pressure to get the slab back to grade. By continuously monitoring elevations, we are guaranteed that nothing will be over-lifted.
4. We check the final grade. After the injection process has been completed, we use survey equipment to re-measure the entire surface. We want to make sure that the numbers reflect the runway smoothness tolerances required by the FAA. In the case where adjustments are required, we will make them then and there during the same visit.
5. We seal and clean up. We seal the injection ports so the runway surface remains flush. There are no bumps, lips, or debris in the area afterwards. Since the foam sets quickly, down time is minimized.

The entire procedure is usually completed in a very short amount of time, which is great news when working with an active airfield.

Here is a key distinction between using polyurethane foam injection to level runways as opposed to traditional techniques such as mudjacking. Polyurethane foam is lightweight. It won't add undue weight to weak subgrade, which can be an issue in sandy, wet conditions typical of the 32807 area. Plus, it's waterproof and won't wash out like regular grout during the heavy downpours here in Florida.

Need advice on if your runway can be treated this way? Give us a call!

Void Filling and Soil Stabilization as a Part of the Same Mobilization

Here's something a lot of airport managers don't know until we mention it. When our crew is already on-site for airport runway leveling, we can also handle void filling and soil stabilization during this same visit. One mobilization. One setup. Two fixes before we're done.

Voids under airport runway slabs don't happen instantly. They develop over time through Florida's sandy soil eroding, washing out in heavy rains or compaction from load cycling. We often see this in Azalea Park, FL near Orlando Executive Airport, where the water table is very close to the surface. This causes subsurface water to flush fine material from under concrete slabs creating gaps which progressively enlarge every season.

Why It Makes Sense to Combine Them

Raising a concrete slab without treating the soil below it is like bandaging a leak. Yes, the slab goes back up. But, if the soil below is still loose and hollow it will likely settle again. We treat both issues together:

• We use ground-penetrating radar to map the runway section for voids and soil density.
• We inject polyurethane foam to fill the voids and restore sub-slab support.
• We do soil stabilization in areas with loose soil or organic content that could erode.
• We verify leveling and confirm load capacity before reopening the runway.

The polyurethane foam for void filling expands to fill irregular cavities, and cures in minutes, not days. That is critical because runway time is money.

With soil stabilization, we are injecting deeper into the native soil that's lost its load bearing capacity. Sandy soils along South Goldenrod Road and throughout the 32807 zip code are especially vulnerable to it. It works by binding loose particles together into a solid layer immune to washout.

And here's a direct benefit to you. When you schedule both services during one visit that means your runway stays closed for just one, instead of two. Less disruption to your operation. Less coordination headaches. We've done it enough times in Azalea Park to know that combined work can save a considerable amount of time and help you get your airport back to normal quickly.