In the construction of mass concrete structures such as dams and foundations also feasible for the rapid placement of highways and runways specially-proportioned no-slump concrete can be transported, placed and compacted using regular earth-moving and rock-fill construction equipment. Nicknamed "rollcrete," but designated roller compacted concrete by ACI Committee 207, the dry concrete material receives its name from the vibratory rollers used to compact it. One authority defines roller compacted concrete (RCC) as damp gravel fill blended with cement. RCC differs from conventional concrete mainly in its dry consistency. It is so dry that it may be better to consider RCC granular fill rather than concrete when trying to control its consistency during placement.
One advantage of using this no-slump concrete is that it can be placed using large-volume equipment: either conveyor, bottom-dump trucks or a combination of both. More concrete can thus be placed in less time and at lower cost. Though RCC must be wet enough for the cement paste to bind the mass together, it must also be dry enough to support the weight of the vibratory equipment. Slump control of RCC is thus completely reversed from that of conventional concrete. Tests have shown that RCC has properties for the most part similar to those of conventional concrete. The differences that do exist are primarily due to the lower water and cement contents and the higher aggregate proportions found in RCC (RCC typically has 40 percent less water and 30 percent less paste than conventional concrete).
Willow Creek Dam, under construction in Oregon, will be the world's first gravity dam built entirely with roller compacted concrete. With its higher placement rates, lower costs and improved properties, RCC is further extending the capabilities of Portland cement concrete.