Abstract: The disclosed method and apparatus for the downward transfer of concrete eliminate separation of concrete ingredients and drop impact of concrete during concrete placing across a high head, by intermittently feeding concrete to an air-tight chute from the top end thereof while normally keeping the chute top end closed airtightly, the chute having at least one flexible portion adapted to be collapsible upon removal of concrete thereform.

Abstract: A concrete feeding tube, hereinafter referred to as a "tremie tube", is used to feed concrete grout or the like underwater. This tremie tube consists of an outer tube having desired rigidity and a number of through-holes, and an inner tube having desired pliability, the lower end of the inner tube being adapted to be closed with a closure means. The tremie tube is so designed as to be lowered vertically into a body of water with the lower end of the inner tube being closed with the closure means. So lowered, water is introduced through the aforesaid through-holes inwardly of the wall of the outer tube so as to collapse the inner tube with a resulting decrease in buoyancy of the tremie tube. When the lowered end of the outer tube reaches the water bed then fresh hardening-material, such as concrete grout, is fed into the inner tube under pressure so as to inflate the inner tube.