Paving contractors, road builders and even government agencies are turning to Roller Compacted Concrete as the pavement of choice in larger numbers as the acceptance of Roller Compacted Concrete, also known as RCC, grows across the United States. RCC offers unique qualities different from traditional concrete or asphalt that make the pavement an economical, fast-construction candidate for many applications previously reserved for asphalt or conventional concrete.
RCC has been traditionally been used for surfaces carrying heavy loads at low speeds because of its relative coarse texture, but in recent years RCC has been selected as the pavement of choice for a greater number of commercial and industrial applications. Cities such as Columbus Ohio have started using Roller Compacted Concrete for residential streets, and Atlanta Georgia has used RCC for interstate shoulder construction. RCC is primarily used in the construction of industrial and commercial parking areas and low traffic road surfaces.
Typical applications of RCC include:
- Industrial access roads and parking areas
- Shipping yards and ports
- Truck and freight terminals and distribution centers
- Bulk commodity storage and compost areas
- Aircraft parking areas
- Urban, rural and park roadways
- Large commercial parking lots
- Temporary travel lanes
RCC is also being used in pavement systems for higher traffic speeds serving as base for traditional concrete or the lower lift in a two lift paving operation.
There are many benefits to the use of roller compacted concrete, but the main factor is the RCC can be constructed faster and cheaper than traditional concrete and multiple lift asphalt pavements. RCC can be constructed fast because it is typically placed with asphalt type paver equipped with a standard or high density screed, then compacted with rollers. Unlike conventional concrete the use of forms, dowels, reinforcing steel and vibration are not used. Additionally transverse joints are not required, however when project specifies they must be present the joints are spaced farther apart than conventional concrete.
The cost savings associated with RCC is attributed not only to the ease of construction, but the material also uses less Portland Cement the most expensive ingredient in conventional concrete. The specific savings associated with the use of roller compacted concrete is dependent on the complexity of the construction, size of the project and specified mix design.
Additional benefits of RCC – Roller Compacted Concrete
- Durability and resistance to chemical attack
- High freeze-thaw durability even without the use of air entrainment
- High strength capable of supporting heavy repetitive loads without failure
- Reduced cracking and shrinking
- Rigid surface eliminating rutting except in areas of heavy tire chain or studded tire use
- Resists abrasion even under heavy traffic loads and volume
- Light colored surface reduces the required lighting for parking and storage areas
- Light vehicles and cars can travel on RCC soon after completion
While the benefits of RCC are numerous it is important to understand there are also some limitations to the use of roller compacted concrete. For example the production of large quantities of RCC requires specialized equipment. While a transit mix truck can mix RCC the mixing time is significantly longer than conventional concrete and the amount of RCC than can be mixed in the truck is reduced because the dryness of the RCC mix. Also the surface of RCC may not be suitable for high speed traffic without diamond grinding.
Other limitations of RCC
- Adjacent slabs and multiple horizontal lifts must be place within an hour to ensure good bonding unless a cold joint is planned
- Pavement edges are more difficult to compact causing most specification to require 96% modified proctor density on cold joints
- Admixture usage on RCC may be higher than traditional concrete because of the dryness of the material
- RCC paving in hot weather requires extra attention to reduce the possibility of water loss and evaporation
When considering the versatility of RCC, its ease of application in comparison to conventional concrete and its durability as compared to asphalt it becomes clear the roller compacted concrete is a suitable paving substitute. When considering the rising cost of oil and petroleum based products such as asphalt it becomes clear that RCC is likely the paving material of the future.