Roller Compacted Concrete (RCC) is a mix that uses only enough water to hydrate the Portland cement. The consistency is not like ordinary concrete (slurry), but is just barely dampened aggregate and cement.
Cement takes very little water to activate the hydration process. And excess water severely weakens the finished product. I used to fight with contractors all the time over how much water to use in the mix. They wanted a thin slurry because it’s much easier to work.
https://en.wikipedia.org/wiki/Roller-compacted_concrete
Roller-compacted concrete (RCC) or rolled concrete is a special blend of concrete that has essentially the same ingredients as conventional concrete but in different ratios, and increasingly with partial substitution of fly ash for Portland cement.[2] RCC is a mix of cement/fly ash, water, sand, aggregate and common additives, but contains much less water. The produced mix is drier and essentially has no slump. RCC is placed in a manner similar to paving; the material is delivered by dump trucks or conveyors, spread by small bulldozers or specially modified asphalt pavers, and then compacted by vibratory rollers.