Full Article on Road Rock Recycle
Texas Materials has been servicing the Central Texas area since its birth in 1982 as a family-owned sealcoat and asphalt paving company. Since then, it has grown to become a leading choice for asphalt production and paving services, ready-mix concrete, sand and gravel and crushed stone. The company is part of the Texas Materials Group, which includes Gulf Coast, TexasBit and Texas Concrete.
In 2019, the Cedar Park-based company had a portfolio of 11 asphalt plants, five ready-mix concrete plants, one crushed stone plant, two sand and gravel aggregate plants and three railroad-based aggregate terminals. It also runs full-range asphalt paving and maintenance construction businesses in the San Antonio, Austin and Waco areas.
Earlier this year, the company won two TXAPA Quality Pavement awards for two demanding jobs it undertook. Texas Materials Vice President and General Manager Mike Brown explained the TXAPA Quality Pavement Awards evaluate and judge pavements of association members and the best ones are voted on to decide a winner. The company was proud to be named tops in two categories.
The first of these awards came in the Large Airport category and Texas Materials won for its work with the Burnet Municipal Airport.
The Burnet Municipal Airport project included 36,371 tons of asphalt produced by Texas Materials’ Liberty Hill asphalt plant with aggregates from its Marble Falls Quarry, which was used to pave the runway. The company utilized five active rollers to compact the mix—three 10-ton vibratory steel wheel rollers, and two 25-ton pneumatic rollers.
“This type of job requires enough rollers to achieve consistent compaction and thorough coverage of the mat,” Brown says. “Typically, with asphalt paving, it is dried out with a big dryer with a direct flame that dries and heats up the aggregate. Then a hot asphalt binder is added to it produced at 300 degrees Fahrenheit, put into a silo and then dropped into trucks. Deliver the asphalt paving mix to the job site into a machine that places it smoothly and at a uniform thickness.”
From here, it is compacted with rollers, which are typically double drum steel rollers and pneumatic rollers that have rubber tires. Brown explains that happens whether it’s an airport or highway.
“Production and trucking were coordinated to provide a steady constant stream of material to the paver, ensuring steady, constant paver speed and consistency when compacting,” Brown said. “We made sure we had adequate time and production capability to complete each pass on the same day it began. We also made sure the operator avoided changing direction on the fresh mat whenever possible — and that they pulled off onto an adjacent area when stopping was unavoidable.”
The airport project specification requirements were a little tighter than a residential subdivision or city street, which presented some challenges to the Texas Materials team.
“The tolerance on the pavement elevation, smoothness and thickness needed to be a little bit tighter and we used a GPS control system on our paver that helped us achieve a closer grade tolerance,” Brown said. “Our compaction team had to be very careful because it’s hot and would deflect, so they monitored temperatures closely. Our whole team was on board and up to the challenge.”
That team included an asphalt paving crew, delivery trucks and the quality control technicians at the hot mix plant and on the job site and quality assurance personnel.
“There are always logistical challenges but nothing that as a team we couldn’t overcome,” Brown says. “In both jobs that won awards, it took a lot of teamwork, communication and partnering to be successful — to meet the quality for the award categories. Our team, starting with the estimators, construction superintendents and technicians, working with engineers and inspectors and with the crews who produced, delivered, placed and compacted the mix, were all outstanding and delivered a real good execution.”
The second TXAPA and NAPA Quality Pavement Award came in the Special Award category for the project FM 3470 in Killeen for the Waco District, where Texas Materials did a level up using 47,348 total tons of asphalt on a 2-inch HIR Item 358 above a 1-inch surface TOM Item 347.
“What was unique about the 3470 project is that TxDOT had two inches of hot-in-place recycling that they did first. We had a subcontractor working for who us came in and did two-inch recycling and we came in after them and did a one-inch TOM overlay,” Brown said. “TxDOT wanted a higher-performing project, so they increased the asphalt binder quality from a PG7022 to a PG7622 and changed the surface aggregate classification from a Class B to a Class A and also added a ride spec, which provided us with both opportunity and risk.”
He explained that the ride change specification became a bonus/penalty situation, meaning that if both companies placed and compacted it very precisely and improved the ride significantly, it would receive a bonus, but if they couldn’t they would get a penalty. To no surprise, Texas Materials was successful.
The major challenge of the project was that it was in a high-traffic zone with two lanes in each direction and a center double left turn lane with approximately 40,000 vehicles a day travelling on the road. Also key to the project was collaboration with TxDOT and outside engineering on a revised traffic control plan to safely manage the traveling public and internal construction traffic. Additionally, the team had to be vigilant to prevent the HIR from melting the traffic cones and catching fire to adjacent grass.
“The challenge was getting the work done under these traffic conditions, minimizing interruptions and accidents. We did pretty well,” Brown says.
The hot-in-place recyclable equipment was unique, as it was basically a thousand-foot long train with direct fire heaters that were heating the pavement up at one quarter inch depths in order to scarify and windrow a total of two inches of the existing mix. Then an emulsified rejuvenator was added to the windrowed mix and the recycled/rejuvenated mix was run back through a paving machine and re-placed and compacted.
“But it looked like fresh hot mix, the subcontractor placed the recycled mix on grade and it was very stable. Then we came on top of that with non-tracking asphalt membrane, followed by the 1-inch TOM mix on top of the non-tracking tack product,” Brown said. “That made a three-inch pavement brand new structure that is expected to provide more than ten years of rut and crack-resistant, smooth, quiet, durable pavement for the traveling public. It was both innovative and unique and came out looking great.”