You may have heard of the term Roller Compacted Concrete (RCC). But what is RCC and when is it used? RCC blends the economy of the asphalt paving process with the durability and performance of concrete. It is typically used for heavy duty applications (civil, manufacturing, etc) or areas that require low maintenance roads (rural roads).
RCC mix is loaded into an asphalt paver and placed prior to compaction with a vibratory roller.
The concrete mix itself is very dry and is designated as “zero slump". The lack of excess moisture in the concrete allows for contractors to place the material without using forms. RCC is typically mixed at a batch plant, loaded into a dump truck and transported to the job site. It is then loaded into an asphalt paver where it is placed in long stretches.
Compaction is key when using RCC. First, the subgrade upon which you are placing your RCC needs to be fully compacted. A rigid material like concrete is only as strong as the soil it sits upon, therefore proper compaction methods must be used prior to placement. Second, the RCC needs to be fully compacted once placed. Proper compaction of the RCC itself is crucial to the long term strength and durability of the concrete.
The RCC process does usually result in a rough finish. To improve surface smoothness and texture, RCC can be diamond ground or a thin asphalt or concrete overlay can be applied.
Because there is a lack of excess moisture in these mixes, the concrete needs to be cured thoroughly in order to keep the mix water in the concrete matrix. Lack of curing can result in lower strength, plastic shrinkage cracking and other problems.
If you want to learn a little more about the subject, you can check out this video from the American Concrete Institute.