Q.: Can the water-cement ratio be increased in the original mix if vacuum dewatering is to be employed?

A.: The manufacturers of vacuum dewatering equipment often say that the water-cement ratio can be increased if their equipment is to be used. There is undoubtedly a limit to the amount of extra water that ought to be added, however, because a large excess of water would promote segregation and lead to other problems. Vacuum dewatering can greatly reduce the water-cement ratio because a considerable amount of water is removed during the dewatering operation without removing any of the cement.