The New Jersey Concrete Promotion Council (NJCPC) staged a roller compacted concrete (RCC) placement demonstration on the property of major Garden State precast producer, Kerr Pipe. Members of the NJCPC Paving Team, including Tom Mackleer and Scott Franz of Hercules Cement, and the newest members of the New Jersey Concrete and Aggregate Association — Bob Berger and Rex Busa of Folsom-based Kerr Pipe — convened after the team convinced both the producer and the contractor, R.E. Pierson Construction Co., to employ the special material for a heavily-trafficked plant entranceway.

“Our original plan was to use a combination of conventional concrete and asphalt,” says Busa. “We were considering poured-in-place concrete in the most critical areas and asphalt in the traffic lanes. Tom Mackleer of Hercules Cement pitched the idea of RCC for the entire project. After careful consideration and research, we were convinced RCC would not only meet but exceed our requirements.”

The team joined forces on all elements of the demonstration — the mix design, equipment, labor, invitations, and food. Early the week of the scheduled demonstration, the weather was sunny and mild in South Jersey. Faxes came in by the dozens to NJCPC offices until the count reached 70 registrants. Everyone from the DOT and other transportation authorities, to county engineers, architects, engineers and suppliers were signed up to witness the placement of 18,000 sq. ft. of RCC. Then came the rain.

“RCC can be placed in extreme climates; however, rain or even the threat of rain is not one of them,” notes Mackleer. “Excess moisture in the sub-base or on the surface can cause a sharp reduction in this product's service life.”

Looking for the first opportunity to complete the project, team members watched weather forecasts. When a small weather window opened, the paving team worked very quickly to reschedule the event. All agreed to pave at the first opportunity, as a chief concern for Kerr Pipe was the interruption of its day-to-day business.

Because Mother Nature cooperated the following week, offering weather in the mid-40s with light winds, preparation and test pours were completed on Tuesday. The demo was held the next day. Twenty-five of the original registrants came out to watch 380 yards of RCC pavement placed.

“On the first day, we placed approximately 100 yards on a section adjacent to the office,” reports Mackleer. “We wanted to give R.E. Pierson's paving crew and Kerr Pipe's batching personnel a chance to get familiar with the product and determine the quantity of material that could be batched.”

The subsequent demonstration proceeded as planned. The balance of the RCC was placed in straight runs 14 to 16 ft. wide. R.E. Pierson's crew was finished by mid-afternoon.

RCC is a zero-slump concrete mixture placed and compacted with the same equipment used for asphalt. In this instance, the mix design created by Scott Frantz of Hercules Cement consisted of 1,725 lbs. of sand, 1,725 lbs. of ⅜-in. aggregate, and 525 lbs. of cement at a 0.42 water/cement ratio. “After running various mix designs in our lab, this one provided the best results,” he says. “It produces a smooth, dense surface that looks very similar to a finished course of asphalt, but can stand up to all types of traffic. Because of its low water-cement ratio, RCC typically has compressive strengths greater than conventional concrete at the same cement factor.”

The RCC pavement process requires no forms, surface texturing or sealing. Its high-strength properties, combined with ease of construction and high rate of production, make it a suitable alternative to flexible pavements. The RCC at Kerr was placed at a depth of 7 in. and compacted down to 5 in. with a 10-ton vibratory roller. Immediately after the compacting operation, a concrete curing compound was applied. The RCC process requires no additional finishing.

While R.E. Pierson supplied the labor and equipment from its paving crews, Kerr provided the zero-slump concrete for the entire project using two Besser mixers located in central mix batch plant. Kerr's computer batching system ensured the consistency and speed required for high-volume paving.

“The sheer volume of traffic demands a durable, high-strength, long-lasting product,” says Busa. “A minimum of seventy 80,000-lb. dump trucks, pipe trailers and heavy industrial traffic traverses this location daily.”

At the end of the day, Kerr Pipe officials got what they were looking for — a capital improvement to their property completed on time and under budget. “Over the years, the grade level around this facility grew and we had a problem with water running back into our building,” explains Berger. “We came up with a solution that addressed all of our concerns, a product that could be manipulated for proper drainage, exceptional strength and durability, as well as be maintenance free. Roller compacted concrete was the right choice.”

This is the fourth RCC job on record completed in New Jersey. The NJCPC paving team is optimistic that additional RCC projects will follow — one request came in solely as a result of the demo. While the product is still considered by many to be in its infancy, the NJCPC Paving Team recognizes the strong interest in RCC and looks forward to promoting the material as a flexible-pavement alternative.

Adapted from a case history prepared by the New Jersey Concrete Promotion Council.