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Chip Seals Key to Preventive Maintenance for Texas Roads

Ergon Seal Coat Application in Progress

Background

As part of the San Antonio 2017 District-Wide Seal Coat Project, 3.7 miles of FM 2200 in Medina County, Texas, were set to receive a chip seal application. The owner of the project, Texas Department of Transportation (TxDOT), has historically applied emulsion-based chip seals on rural roads such as FM 2200 every seven years as a preventive maintenance measure, even with no significant distress present.

Ergon Seal Coat CHFRS2P

Chip seals are designed to treat top-down fatigue cracks, raveling and oxidation, extending a road’s service life for five to seven years. They also provide increased surface friction for greater protection for commuters. In a chip seal application, an asphalt binder is applied to the existing roadway, sealing cracks less than ¼ inch. Aggregate, which is used to enhance surface friction, is then applied and rolled into the binder.

TxDOT contracted Clark County Construction of Texas, Inc., for the FM 2200 chip seal application. Ergon Asphalt & Emulsions was selected to supply the chip seal emulsion, CHFRS-2P, from its Pleasanton, Texas, facility. CHFRS-2P is a cationic high float emulsion that provides greater durability than conventional chip seals and a stronger bond with the aggregate applied over the emulsion. As an extra benefit, return-to-traffic time for CHFRS-2P chip seals is usually 30 to 50 percent faster than conventional chip seal emulsions.

Ergon Seal Coat Application in Texas

Application Highlights

In a one-day application, CHFRS-2P was shot at 0.42 gallons per square yard followed by the application of Grade 4 aggregate, supplied by Anderson Columbia, at 115 square yards per cubic yard. Shortly after application, the road was reopened to traffic.

Results

Eleven months after application, a TxDOT representative noted the road’s consistency and commented that the seal coat on FM 2200 was still holding up well. The agency plans to continue using CHFRS-2P on emulsion seal coat projects throughout the state.

Ergon Seal Coat CHFRS2P Finished

Chip seals are one of many preventive maintenance and pavement preservation treatments used to protect and extend the service life of a road. Contact your local Ergon Asphalt & Emulsions salesperson to find out more information on how chip seals and other solutions can help meet the specific needs of your road.

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Cationic High Float Treatment Relieves Base Failure

High Float Treatment

Background

Three miles of FM 2105 along the west side of San Angelo, Texas, had base failures and displayed alligator cracking due to consistently large volumes of heavy traffic.

The only way to truly correct base failure is to dig up the road, replace with new material and resurface. In the case of FM 2105, completely reconstructing the base and resurfacing would cost hundreds of thousands of dollars. The Texas Department of Transportation (TxDOT) needed an inexpensive treatment that would mitigate damage to FM 2105 and prevent the road from completely giving out, until funds became available for reconstruction and resurfacing.

Due to its unique curing properties, it was determined that a chip seal application using a cationic high float for the binder would be the best and most affordable option. Ergon Asphalt & Emulsions, Inc., would supply the emulsion, CHFRS-2P, for the project and be onsite to provide assistance when needed.

How Chip Seals Work

In a chip seal application, emulsion is sprayed on the road to fill crevices or cracks ideally less than 1/4” in size. This helps prevent water penetration into the vulnerable base material, which ultimately keeps cracks from widening and load-related damage from occurring. A layer of aggregate is then applied. A pneumatic roller is used to compact the material (or set the aggregate into the emulsion) and finally, a rotary broom is used to remove excess aggregate, creating a smooth riding surface. For cracks 1/4” and larger, a high-quality hot melt crack sealer should be applied.

FM 2105 Application Highlights

The three-mile section of FM 2105 was chip sealed in one day, with temperatures around 90°F. The CHFRS-2P emulsion was sprayed onto the surface at a rate of 0.35 gallons per square yard followed by the application of Grade 5 aggregate, which is sized 1/8”.

The chip seal was applied one lane at a time, first in a two-mile section, then followed by application to the remaining mile. Traffic was able to return to the road within two hours following the chip seal, and there was no bleeding or abnormal aggregate loss.

Project personnel were pleased with the outcome and noted the application as a fast and simple process for sealing badly distressed pavement.

Thanks to the chip seal application, TxDOT was able to meet the immediate needs of the road at a cost that fit their budget, while extending the service life of the road for nearly two years. Approaching one year since application, FM 2105 is still holding up well.

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