Underwater concrete immediately conjures up images of bridge pillar foundations, piers and locks. But car parks, cellars and other construction works under groundwater level should also be included. Because lowering the ground water level by extracting water is today rarely possible or permitted.
Working at ever greater depths underground also has consequences for construction methods. Underwater concrete is thus finding increasing application as waterproof flooring in cofferdams. The ballast floor must be sufficiently heavy in order to withstand the upward pressure of the groundwater after pumping out the cofferdam.
The most important property of the processing method is that no segregation or washing out occurs while pouring. The addition of large quantities of fine filling material (fine sand or pulverised coal fly ash) keeps the mixture homogenous during application and hardening. Compaction of concrete underwater is not an option. Which is why this ready mixed concrete contains a certain degree of self-compaction properties.