52 



3. Other Methods of Making Cement Pipe. 



The lack of uniformity in the pipe made with a dry mixture tamped by 

 hand as described above and the porosity of the pipe, have led to other 

 processes of making pipe, some of which are still in the experimental stage. 

 Two methods have been used, machine tamping and the wet process. 

 Machine tamped pipe. 



Machine tamped pipe is made by a number of plants in the West includ- 

 ing one at Peachland. The pipe is made with a comparatively dry mixture 

 much in the same manner as hand made pipe, but the mixture is thorough- 

 ly tamped by a mechanical tamper of email cross section which tamps 

 rapidly and gives a high degree of compression. The inside core also ro- 

 tates during the tamping processes and this gives the inside of the pipe a 

 very smooth surface. The pipe obtained by this process is a very dense 

 pipe. It should be very uniform and superior to the hand made pipe, 

 especially when a pipe is desired for pressure heads greater than the hand 

 made pipe will stand. 



The pipe is made with a bell end similar to sewer pipe. This requires 

 more material than the shiplap end obtained with the hand made pipe 

 which increases the cost. 

 Pipe made by wet process. 



To make pipe by the wet process, a wet mixture of cement mortar or 

 cement concrete is poured in the mould and after the mixture has hardened, 

 the moulds are removed. As this takes several hours, only a few pipes can 

 be made per day. For a large output several moulds would be needed and 

 the cost of the plant would be high. However, the moulds need not be as 

 strong as those used for hand tamping and could be obtained at a much 

 smaller cost. The increased cost of plant would be overbalanced, if a 

 large quantity of pipe was made, by the saving in labor and also by the 

 saving in cost of material because a pipe equal in strength and imperme- 

 ability could be obtained with less cement. 



To reduce the number of moulds it has been attempted to accelerate the 

 hardening of the mixture by heating it with steam. This process, how- 

 ever, is still in an experimental stage. The U. S. Department of Agricul- 

 ture, through its Irrigation Investigations Office, is investigating the wet 

 method of making pipe. The U. S. Reclamation Service has also devised 

 methods of making a wet mixture cement pipe at a reasonable cost for the 

 Tieton irrigation project in Eastern Washington, and for other projects. 

 Their results have not yet been published. 



REINFORCED CONCRETE PIPE. 



There is a great field for a concrete pipe which will stand moderate 

 pressure and can be manufactured at a cost which will compare well with 

 that of wooden pipe. The hand tamped plain concrete pipe has sufficient 

 strength only for low pressures, and machine tamped pipe or pipe made 

 by the wet process has not been sufficiently tested to know what heads it 

 will stand, though they are probably safe for at least twice the pressure 

 resisted safely by hand made pipe. Reinforced concrete pipe has been used 

 successfully for pressures above 100 feet and is guaranteed by some pipe 

 manufacturers for pressures as large as 150 feet. Reinforced concrete 

 pipe consists of a skeleton of iron or steel imbedded in the concrete shell 

 of the pipe. The reinforcement is made of rods or bars of metals, or some 

 form of expanded metal or wire mesh. For small pipes the circumferential 

 reinforcement is often made as a spiral of wire. For larger pipes the re- 



