Long favored by industrial builders as a super-tough surface for access lanes and truck parking areas, roller-compacted concrete (RCC) may soon be the #1 choice for low-speed surfaces of all kinds.
A new finishing agent tested last year in 4 states has captured the attention of municipal and commercial road builders. Known as RCC Surface Pro™ , this spray-on solution works with power troweling to smooth and strengthen RCC’s top surface, virtually eliminating the need for asphalt topping.
How it works
Developed by Solomon Colors, Inc. , RCC Surface Pro uses breakthrough technology specifically designed for RCC. The product is made with proprietary silica technology on a nanoscale smaller than silica fume.
“The special formula reacts with cement and lime in the RCC mixture to promote rapid hardening and binding without affecting the water/cement ratio,” explains John Anderson , director of business development for Solomon Colors.
Roller Compacted Concrete (treated with RCC Surface Pro, power trowelled, and broom finished) being installed as a road surface at the Resurrection Catholic Cemetery in Chicago, IL.
Placement methods are simple and straightforward. Crew members spray the formula onto the RCC surface immediately after the final roller pass. The surface is then power-troweled and broom-finished, giving it the same appearance as standard concrete.
“Color can be added to the formula to create red, brown or black tones in the finished surface,” Anderson adds.
The new method also helps contractors finish jobs faster. In most cases, pavements can be reopened to traffic as soon as the wax curing compound dries, usually within 24 hours of placement.
Tests reveal toughness
The idea of using RCC as a final riding surface has widespread appeal, notes Anderson. Still, the engineering community has expressed doubts about durability, especially since RCC has no air entrainment. To address these concerns, Solomon teamed up with Prairie RCC champion Theron Tobolski to gather proof.
“We took 4 live samples of treated and untreated RCC from a 2014 road placement in Cook County, Illinois,” Anderson says. The samples, each measuring 3’ x 3’, went to Nelson Testing of Schaumburg, Illinois, where experts performed ASTM tests on freeze-thaw durability, salt surface scaling, chloride penetration and abrasion resistance.
“The results were phenomenal,” Anderson reports. “After 300 freeze-thaw cycles, the treated surface increased in freeze-thaw durability by 15% more than the untreated RCC.”
On salt penetration, the troweled surface had an 85% improvement over unfinished RCC. Abrasion resistance showed a 48% improvement.
“This shows that surfaces densified with RCC Surface Pro won’t wear away. In fact, they are essentially high-performance concrete that delivers the equivalent of 6,500 psi at the surface,” Anderson says.
Chicago-area cemeteries try it out
In Cook County, Illinois, engineering firm Ament Design has tapped the new approach in its work with Catholic Cemeteries of Chicago, which oversees some 45 cemeteries in and around the city.
Last spring, Tobolski and the Prairie team partnered with J & R 1st in Asphalt of Hickory Hills to present RCC as a pavement option to Ament Design engineers and officials from Catholic Cemeteries. After a successful demo placement at Prairie Yard 8 near O’Hare Airport, J & R crews used RCC to construct new roads at All Saints Cemetery in Des Plaines, Illinois.
“These were country-lane style roadways with no curbs. We placed a 5-inch lift of RCC which was topped with 2 inches of asphalt,” says Carmen Arvia, the project engineer for Ament Design.
The job helped J & R workers get comfortable with RCC. “Then, after seeing the video of RCC Surface Pro being used with power-troweling, we were ready to experiment with that approach,” says Arvia. “One of the unknowns was whether use of a standard asphalt paver would achieve the same results as the projects where what we would consider a high-density paver was used.”
Test job in the maintenance yard
Crumbling asphalt in the maintenance yard at Maryhill Cemetery in Niles, Illinois provided the perfect test site for the troweled surfaces. “We had 55,000 square feet of paving that had been damaged by heavy truck and maintenance equipment traffic,” Arvia explains.
Other contractors and owners came to watch the power-troweled placement, hoping to learn more about the method. Concrete contractor R. Olson provided a power trowel and experienced finisher to help with the work. Representatives from local School District 15 and the Illinois Tollway were on hand to observe.
J & R workers and Catholic Cemeteries were surprised to find how well the treated surface took to the power trowel, Arvia says. “Everyone remarked on the final appearance — it really looks like traditional, broom-finished concrete.”
Solomon colors had only planned to do a 50’ x 70’ test section, but the results were so remarkable that Catholic Cemeteries gave on-site approval to use the finish for the entire project.
The remaining 40,000-square-foot job took 2 days to complete, followed by 3 days of curing time with a wax-based curing compound for extra strength before the heavy duty maintenance equipment was allowed on the pavement.
In September 2014, Catholic Cemeteries began construction on the next power-trowel job at Resurrection Cemetery in Justice, Illinois, This time, new roads were built with a single 6-inch layer of RCC, with 90% of the 27,300-square-foot job placed in one day.
This year J & R plans to construct more roadways at St. Casimir’s Cemetery on Chicago’s South Side, experimenting with adding a dark grey pigment to RCC Surface Pro so the new lanes will closely resemble existing asphalt surfaces.
Long-term cost advantages
Arvia reports that Catholic Cemeteries saw tear-out and replacement costs about 10% higher with power-troweled RCC than with traditional asphalt, adding that this was easily outweighed by the 20-to-30 percent maintenance savings expected over the long term.
“New construction costs were actually a wash, since they were able to use a slightly thinner stone base than traditional excavation without the added cost of asphalt overlays for aesthetics,” he adds.
“All in all, RCC finished with RCC Surface Pro may add 30 cents per square foot to any RCC project, but the added durability and reduced construction time is well worth it,” says Arvia.
A worldwide solution?
Solomon officials expect to see even wider use of RCC Surface Pro as paving contractors seek better alternatives for their customers.
“The formula and placement techniques were tested extensively in Ohio, Texas, Georgia and Illinois last year, and right now we’re seeing some real interest from European companies as well,” Solomon’s Anderson says.
In the U.S., big box stores are looking at it for drive lanes and parking lots, he adds. And the $2-billion Echowater Recovery Project near Sacramento, California will create a 96-acre water basin, constructed entirely of Surface Pro trowel-finished RCC. “That should really put the technique on the map,” says Anderson.
“This is the single greatest innovation in roller compacted concrete I have seen,” says Prairie’s Tobolski. “It allows smaller contractors to compete with larger contractors for thin asphalt type projects like fast food parking lots and drive throughs. And owners will benefit from the strength and durability of concrete at asphalt costs.”
Here in the Midwest, Prairie Material is proud to partner with Solomon Colors to offer this breakthrough technology for low-speed roads, parking lots, road shoulders, commercial driveways and many other applications. To learn more, talk with your Prairie sales representative
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