RCC (Roller Compacted Concrete)
RCC or Roller compacted concrete was limited to the sub-base of roads and airfield pavements, being called lean concrete or dry lean concrete. RCC became popular due to the fact that it is a simple material to produce and place. RCC (Rolled Compacted Concrete) has a low cement content, about 110 to 120 kg/m3, and uses washed aggregate of concreting quality. American Concrete Institute(ACI) 207.5R-89 defines roller compacted concrete (RCC) as concrete compacted by roller compaction.
Roller Compacted Concrete(RCC) started in the 1970, when the industry switched to environmentally cleaner, land-based log-sorting methods. Their need to build a strong and massive base, and economical solution was equally important: log-sorting yards can span 40 acres (16 hectares) or more. RCC met this challenge and has expanded to other heavy-duty applications.
The first successful application of RCC technology was demonstrated in 1974. The repair of the collapsed intake tunnel of Tarbela Dam proved that the material had more than adequate strength and durability.
Roller Compacted Concrete (RCC) Benefits
The high strength of RCC pavements eliminates common and costly problems traditionally associated with asphalt pavements. Some of the benefits of using Roller Compacted Concrete are:
- Resist rutting.
- Span soft localized sub grades.
- Will not deform under heavy, concentrated loads.
- Will not deteriorate from spills of fuels and hydraulic fluids.
- Will not soften under high temperatures.
Advantages of Roller Compacted Concrete (RCC)
This concrete methodology is economical because it can generate high-volume, high-speed construction. Usually RCC is mixed at or near construction sites, using large-capacity mixers that have the mixing efficiency needed to evenly disperse the relatively small amount of water used. Then RCC is transported using dump trucks and placed into an asphalt paver, which places the material in layers up to 13 meters wide and up to 250 millimeters thick. The placing of the concrete is made in continuous layers and is consolidated by vibrating rollers. Other benefits are:
- Cement consumption is lower because leaner concrete mixtures can be used.
- Formwork costs are lower because of the layer placement method.
- Pipe cooling is unnecessary because of the low temperature rise.
- Cost of transporting, placement, and compaction of concrete is lower, because concrete can be hauled by end dump trucks; spread by bulldozers and compacted by vibratory rollers.
Roller Concrete (RCC) Consolidation
Immediately after placing the concrete, consolidation must be started until the pavement meets density requirements. Achieving these requirements will allow your concrete to have strength, smoothness, and surface texture. Curing concrete will ensure a strong and durable pavement. A water cure sprays or irrigation systems must be applied to the pavement to keep it moist. This process allows the chemical reaction that causes concrete to harden and gain strength to begin and complete. A spray-on membrane can also be used to seal moisture inside. Once cured, the pavement is ready for use. An asphalt surface is sometimes applied for greater smoothness or as a riding surface for high-speed traffic.
Its primary use to date has been in new dam construction and the rehabilitation of existing dams. It has also been used for paving areas that receive heavy axle loads and have had limited use in road construction. By 1997, 150 projects using RCC, including 46 new dams by the US Corps of Engineers, were completed in the United States.