Nestled in the hills of rural Georgia, you’ll discover a unique community dedicated to preserving the scenic terrain surrounding the property. Serenbe Farms is a sustainable development, and a special type of concrete called pervious is upholding their environmental mission.
Mark Rongey, Sales Manager for Walker Concrete, says the development is an interesting concept. “The whole development has been designed around green aspects of building,” Rongey says. “They want to maintain as much of the natural area surrounding the development and then use best practices to keep everything as close to natural as they can.”
The first home was built on the property near Palmetto, Georgia back in 2004. Today, Serenbe Farms is home to nearly 500 residents, and each new addition to the planned community follows a comprehensive land-use plan that encourages conservation. A 2016 phase of the community included a section of new town homes and an office building with retail shops.
Utility Contractor Ronnie D. Jones Enterprises (RDJE, Inc.) was chosen to handle site work and infrastructure development of the 36-acre third phase. Matt Snow, Project Manager for RDJE, says this phase of the project was positioned in tight quarters. “Engineers were constrained by quite a few things,” says Snow. “There was no room for things you’d use in typical storm water management. No concrete pipe, very few structures and there wasn’t room for any kind of holding pond.”
To service the compact job site and stay within the development’s land-use plan, the solution turned out to be a unique type of pavement called pervious concrete.
“This particular project included a large entrance into an underground parking structure for an office condominium complex,” Rongey says. “This required about 126 yards of pervious concrete. The difference between pervious and a standard concrete mix is that this mix is designed with very low water/cement ratios meaning there’s not a lot of liquid that’s introduced into this mixture. It’s very coarse. It doesn’t have the plasticity that you would get with a normal concrete mix and therefore you really have got a lower set time because of that lower water cement ratio.”
In pervious concrete, carefully controlled amounts of water and cementitious materials create a paste that forms a thick coating around aggregate particles. The result is a material that is highly permeable, made up of interconnected voids that drain quickly. “That is really where this particular type of material excels,” Rongey notes. “It has the ability to handle large volumes of water in a very quick pace.”
Back at the plant, the nature of the mix design required careful coordination with dispatchers to ensure delivery of the product was perfectly timed. “It’s critical that you do not let that concrete sit for too long on these trucks because you don’t have the option of adding water to this particular design,” Rongey explains. “It has to be placed very quickly very soon after batching because you’re hitting it with just a light amount of water and it’s already begun to hydrate and you need to get it down and compact it and in place as quickly as possible so as not to disrupt the actual effectiveness of the end product."
RDJE relied on Walker Concrete’s expertise and experience to assist in perfecting the mix design and handling the unique placement of the project. “Walker was excellent,” says Snow. “They had a quality control here constantly. They were constantly checking the mix making sure the plant was right on top of it. They superbly pointed us into a lot of potential directions that could help us next time.”
To maintain a constant rate of production, five trucks were dispatched to the rural job site. “We had to make sure that differentials between mixes and loads did not occur,” Rongey says. “That’s very important with pervious concrete. We had to maintain high levels of quality control during this pour to ensure that the contractor had a continuous flow of concrete that wasn’t sitting on the job waiting but was actually ready as soon as it got here.”
The end result: A driveway made up 8 inches of fiber-reinforced pervious concrete atop a subgrade layer of stone. The entry easily handles sudden storms without overwhelming nearby drains and structures.
Snow says this is his first experience with utilizing pervious concrete and so far, he remains impressed with the material’s capabilities. “We’re always looking for new things that can help us as well as be appealing and a benefit to owners," he says. "We’d love to try to figure ways to use it even on roadways of certain size and capacity. We would definitely consider it for with future projects."