Driving east on the H-1 Freeway under the Kaahumanu Street overpass, a 1,300-foot stretch of dark brown lanes come into view.
It contrasts sharply with the black asphalt before and after it. Flanked by tropical greens on either side of the highway and with Pearl Harbor just out of sight, this section of the H-1 Freeway is covered in Armorstone. Underneath the Armorstone is a layer of epoxy, a water-repellant resin that protects the road from chemical and weather erosion. It’s the first roadway in Hawaii to receive this special epoxy-Armorstone treatment.
Getting Armorstone to the Island
Armorstone overlay aggregates have been used throughout the United States to increase the safety of roads and bridges. To make it to the U.S.’s southernmost state, Armorstone first had to pass the stringent requirements of the Hawaii Department of Transportation. The rock needed to be durable, polish resistant, and abrasion resistant.
Not only did Armorstone meet these requirements, but engineers were also impressed with the variety of sizes available and liked its color profile: a rustic brown.
“The engineers wanted a color that was attractive but not a distraction to drivers,” Armorstone sales representative Dale Mortensen explained.
Dale sent samples of the product that simulated how the rock would look on the road surface. The engineers liked what they saw. Engineers ultimately chose to use Armorstone crack seal sand. After doing a test patch in Hawaii, the engineers were satisfied with what they saw and decided to move forward with using an Armorstone overlay.
With hundreds of tons of material to ship and 2 weeks of travel on the ocean, the team couldn’t afford to make any mistakes. In the months prior to shipping, Dale and transportation coordinator Nikki Rogers worked with drying plant manager Edgar Villegas and quality control manager Ryan Hogg to ensure that quality product ended up in Hawaii without a hitch.
Overlay aggregate must be bone dry when added to an epoxy overlay, so the crack seal sand was dried and stored in a silo long before it was needed so it could cool and sweat excess moisture. Smaller, heavier pallets were purchased so that the 3,000-pound Super Sacks of Armorstone fit in the narrow shipping container. Every single bag of crack seal sand was inspected to make sure there were no problems.
Washington Rock even adapted to new deadlines when the project was delayed due to the pandemic. In late summer, dozens of Super Sacks of Armorstone arrived safely in Hawaii.
“It was exciting to be venturing into new territories,” Nikki said.
The H-1 Freeway: Hawaii’s Busiest Highway
Originally built in the 1960s, the H-1 Freeway is the oldest and longest interstate highway in the Hawaiian islands. It runs 27 miles along the south side of Oahu, connecting Kapolei on the southwestern side of the island to Honolulu on the southeastern side.
From 2018 to 2019, the Hawaii Department of Transportation (HDOT) replaced “some of the worst pavement on the state system” between Pearl City and Halawa, the most heavily used section of highway in the state. The state also “widened the eastbound shoulder lane between the Waimalu Viaduct and the Aiea Pedestrian Overpass.”
After wrapping up the $68 million project, the HDOT zeroed in on extending the life of the work they had done. They started with the Waimalu Viaduct.
The Waimalu Viaduct Pavement Preservation Project
The Waimalu Viaduct is an elevated section of the H-1 that starts in Pearl City and ends in Aiea. The Waimalu Viaduct Pavement Preservation Project focused on preserving a 1,300-foot section between the Kaahumanu Street and Kaonohi Street overpasses.
The contractor, DBI Services, filled potholes and applied an epoxy surface treatment across five eastbound lanes and seven westbound lanes, including shoulders. The epoxy treatment was done by spreading FASTRAC CE330 epoxy binder over the finished road service. Then Armorstone crack seal sand was applied to the surface. After the epoxy hardened, excess sand was swept away.
“The epoxy treatment allows HDOT to protect and extend the life of our pavement surfaces,” HDOT Deputy Direction Ed Sniffen explained in an HDOT article. “This will help us tremendously in improving the quality and speed of repairs to our roadways.”