With persistent economic concerns and tight budgets, industrial engineering departments and government agencies alike are increasingly searching for long-term and economically viable construction methods.
Now more than ever, concrete is emerging as not only the most durable, long-term pavement solution, but also as the less expensive paving option from an initial investment and life-cycle cost basis.
Perhaps no pavement development has won more friends in the construction community than roller-compacted concrete (RCC). A durable material that carries heavy loads, RCC is a fast, economical pavement used in a variety of applications, including industrial sites, roadways and heavy-duty parking and storage areas. Its use at the Jack Daniel’s Distillery in Lynchburg, one of the first RCC pavement projects in middle Tennessee, proved to be the ideal solution for a recent expansion.
Nearly a quarter of a million people visit the country’s oldest registered distillery every year where Jack Daniel crafted Old Number 7 and where Jack Daniel’s famous Tennessee Sippin’ Whiskey is still made today. The Jack Daniel’s campus consists of 1,600 acres, much of which is devoted to warehouses where the whiskey is matured in handcrafted, white oak barrels. Those warehouses see a steady flow of heavy truck traffic carrying barrels in for aging and transporting them out for bottling. That requires a lot of infrastructure that needs to be built and maintained for coming decades of production.
The Jack Daniel’s Distillery has always used asphalt pavement for its infrastructure, which required a significant amount of maintenance and money each year for repairing potholes, patching and overlaying. In some areas where there is heavy traffic with lots of twisting and turning, concrete has been used to replace the asphalt pavement that was quickly failing under such service conditions.
Taking a shot
In the summer of 2011, Lee Adcock Construction was chosen as the general contractor for two new warehouses and 162,000 sq ft of paving at the distillery, which included an access road and parking and storage areas. Geotechnical engineers performed preliminary evaluations on the subgrade and recommended a pavement design of 6 in. (SN=0.16) of granular aggregate base, 3 in. of bituminous base and 2 in. (SN=0.44) of asphalt topping, yielding a total SN of 3.16.
Based on input from Irving Materials Inc. and Lafarge, as well as research he conducted on his own, Adcock felt that RCC would provide some long-term performance advantages to the project and that it would be a competitive option to asphalt on both a first-cost and life-cycle basis. RCC is a zero-slump concrete that is placed and roller-compacted with the same equipment used for asphalt-pavement construction. Its high-strength properties combined with ease of construction make it an excellent pavement option for large projects where durability and economic considerations are important.
Change of direction
When Adcock suggested RCC as an alternative to asphalt pavement, Jack Daniel’s engineering and maintenance departments were interested in learning more. With the help of Irving Materials Inc., Lafarge and others, technical information was provided to the Jack Daniel’s engineers. A tour of several RCC pavement projects also was arranged, including an automotive plant (2,000 cu yd) and one of Irving Materials’ concrete plants (1,400 cu yd).
“We showed them a fairly large [Irving Materials] RollerPave (RCC) project that was subject to heavy truck traffic since 2003,” said John Curtis, president of Irving Materials-Tennessee. “From the time the RCC was placed, we have done zero maintenance on that road and the pavement looked pristine upon the team’s inspection.”
After visiting these sites, the team realized the significant long-life, low-maintenance advantages that RCC pavement offers. Like all concrete pavements, there also were environmental benefits, such as cleaner storm-water runoff and better nighttime visibility. “As presented to us, we were looking at an initial cost for a 30-year concrete surface that was comparable in cost to asphalt, which has a 10-year life span at best,” said Jim Jeffries, director of engineering and maintenance at the Jack Daniel’s Distillery.
With a structural number equivalent to 3.96, a 6-in. granular aggregate base topped with 5 in. (SN= 0.6) of RCC was simply a better pavement design than the original asphalt specification.
“Based on our research, field observations and cost analysis, the team was convinced that RCC pavement was the best option for the job,” said Adcock. “We then subcontracted the paving work to Robert Smith Inc. because of their extensive experience with RCC placement.”
Following the LEED
Ross Allen, Irving Materials’ technical service director, and Lafarge worked together to develop an RCC mixture based on quality control and quality assurance testing in Irving Materials’ facilities. Their final mix design was a precisely formulated blend of 50% portland cement, 25% slag cement and 25% fly ash with a compressive strength of 4,000 psi after 28 days.
While enhanced strength, durability and other performance properties were the primary reasons for choosing this ternary cement blend, the environmental benefits also were desirable. Its production saves virgin raw materials and makes use of slag and fly ash, which are byproducts from steel-making operations and coal-fired power plants.
“Many of our clients are increasingly looking to achieve LEED standards, and the use of RCC contributes to earning LEED credits in a variety of ways,” said Andrew Smith, project manager at Robert Smith Inc. “By using byproducts from other industries, and not sending them to landfill, we are making the RCC pavement even more sustainable.”
The RCC also included an optimized blend of four different aggregates, which was based on optimum gradation/gradation density and lab trials at Irving Materials.
“We used manufactured sand, which made a better product and offered a sustainable alternative to natural sand,” added John Curtis. “This was the first time in Tennessee where manufactured sand has been used in RCC, and it was a perfect application for this job.”
Rolling it out
In September 2011, the team moved forward with the 162,000-sq-ft paving project, which included a 1,000-ft-long access road, 700- to 800-ft-long rear drives and adjacent trapezoid-shaped parking lots. Construction started with a 6-in.-thick compacted aggregate base, which was put down by Lee Adcock Construction and then fine graded by Robert Smith Inc. The RCC was supplied by Irving Materials using a portable Stephens’ twin-shafted mixer to produce the mixture, which was hauled by dump trucks to the Jack Daniel’s site. The approximate time from the plant to placement of the RCC was 35 minutes.
Robert Smith Inc. placed the 5-in.-thick RCC pavement in one pass with a Volvo ABG 7820 high-density paver. Placement moistures were maintained at 6-7% and checked with a Trident TI-90 moisture meter from James Instruments. Paving widths varied from 15 to 20 ft in the rear drives and parking areas and 26 ft for the access road. Averaging 550 cu yd per day, Robert Smith Inc. placed over 2,500 cu yd of RCC in only six days, which was within 1% of the estimated quantity.
“Construction speed is one of the major advantages of working with RCC,” said Smith. “It eliminates the need to put a middle course binder down and then come back and top it off like you do with asphalt. With RCC, you can place all the material in one lift, so the time savings can be 33-50% faster than asphalt paving.”
Compaction was achieved using a pneumatic rubber-tire roller, followed by 5-ton steel roller. Robert Smith Inc. next applied a white pigmented curing compound per ASTM C309 and cut transverse control joints to one-quarter of the pavement depth at 18- to 20-ft intervals. Final quality-control testing included coring and in-place density measurements with a nuclear gauge. Core samples indicated seven-day strengths in excess of 3,700 psi. These early test cores convinced all parties that the 28-day strength requirements would be exceeded.
Built to last
The Jack Daniel’s Distillery now has a long-life, heavy-duty pavement that will not rut or shove under heavy truck loads.
“Beyond the outstanding performance of the product itself, key to our success was the amount of planning and dedication to teamwork by everyone to create a big win for the Jack Daniel’s team,” said Adcock. “I would definitely recommend RCC to them again as well as my other customers throughout middle Tennessee.”
“From start to finish, it was really a great experience working with the contractors and we were extremely satisfied with the final result,” added Jim Jeffries. “As we continue to expand our infrastructure, we will be looking to use long-term, maintenance-free pavement, and I believe we can achieve that with RCC. The facts that you can drive on the product in a very short period of time and that it is cost competitive are important.” R&B