Casting concrete members with ducts - the ducts being formed by rubber rods or tubes removable by pulling

摘要

A ducted concrete member, which may or may not be reinforced is prepd. by locating a series of rubber tubes or rods within a mould, casting concrete into the mould, allowing it to set, and removing the tubes or rods by pulling on them to reduce their dia.. Pref. the tubes are coated with release cpd. and contain elongated support wires or rods during the casting. After casting the rods or wires are withdrawn from the tubes followed by withdrawal of the themselves. An easy way of making internal, perhaps cable carrying ducts in concrete wall sections etc. Junction boxes through which the rubber tubes or rods pass may be incorporated into the article.