The explosive growth in the use of site-cast concrete in the last 15 years con be attributed to important advances in new techniques and equipment for concrete placement. An important new development is concrete placing by conveyor. The basic reason for this development had been the availability of efficient ready-mixed concrete plants which provide high quality concrete to construction projects of all sizes. Ready-mixed plants developed the capacity to turn out and deliver concrete in 5 to 8 cubic yard batches. Bottlenecks and high production costs appeared when the concrete had to be transported form the mixer to a place of rest. Job conditions such as these led contractors to experiment with new equipment ideas. The ability to deliver an almost continuous flow of material to the job revived interest in conveyors for the placing of concrete. Today successful concrete conveyors, designed specifically for this job, are completely dependable. They combine both horizontal a vertical movement of materials at a rate which equals or exceeds the capacity of placing crews to handle the concrete. The most important consideration in a conveyor is dependability. The placement of concrete once begun must be completed without interruption or the entire cast may be lost. Concrete is one of the heaviest materials which can be run over a conveyor, so the entire supporting structure and drive system must be extremely strong. However, the conveyor must be portable enough to be moved quickly during use so that it discharges concrete at the required final location. Good design and proper balance allow conveyors to meet both the strength and weight requirements.
