THE IRRIGATION AGE. 



215 



SHOOTING CEMENT LININGS INTO DITCHES 



By CARL WEBER, C. E. 



President Cement Gun Construction Co., Chicago 

 (Continued From Our April Issue.) 



THE operation of the Ce- ^^^^^^ gun than to use excessive 



ment-Gun is comparatively I H "~ length of hose. The hose is 



supplied in standard length of 

 50 feet with external couplings. 

 The hose consists of a pure 

 soft rubber tube with canvas 

 backing. The same is subject 

 to strong abrasion as the sharp 

 sand is blown through it. The 

 best soft rubber tubing will be 

 found the cheapest in opera- 

 tion. It may be estimated that 

 a good hose will last from two 

 to three months of hard serv- 

 ice. In emergency cases for 

 straight sections steel pipes 

 may be used in the hose line, 

 where they will last for a short 

 time, while in curved sections a 

 - steel pipe may last only from 

 two to three hours. 



In Fig. 3 a nozzle is shown 

 in operation on the repair work 

 for concrete retaining walls for 

 the Pennsylvania Railroad 

 lines. It will be clearly seen 

 how the hydrated mixture 

 leaves the nozzle and the two 

 cone valve is closed and the Fi - s Shooting the cement into a waii. Note the two i mes f or the dry material and 



HE operation of the Ce- 

 ment-Gun is comparatively 

 simple. The materials, cement 

 and sand, are mixed dry until 

 a uniform color of the material 

 is obtained. This mixing is 

 usually done by hand on a port- 

 able mixing platform. Turn- 

 ing the dry materials 2 to 3 

 times is, as a rule, sufficient. 

 The material should be mixed 

 as needed. No old material in 

 which the cement may have 

 partially set, or wet sand should 

 be used. 



The dry mixture is then put 

 into the upper material hopper 

 (see Fig. 2, page 186, April 

 issue), the upper cone valve is 

 closed and compressed air ad- 

 mitted into tank (B) by open- 

 ing the air valve. Then the 

 lower cone valve opens and the 

 material drops into the com- 

 pression chamber (C) and fills 

 the pockets on the feedwheel 

 (D) and the chamber above 

 the same. After the lower 



compressed air is discharged 



from the upper tank the machine is ready for another 



load. 



the water are plainly shown. 

 It is characteristic of the Cement-Gun, and of 

 greatest importance for the quality of the work, that 



The air from the compressor line enters the piping the material is delivered "dry" through the machine 

 system of the gun at (A), all details of which are into the nozzle, and that the necessary water for hy- 



easily understood from the drawing. 



dration is added at the moment of deposit. The 



The feedwheel (D) is slowly rotated by the air hydration of the material really takes place in the air 

 motor (H) and as it revolves small measured charges between the nozzle and the place of deposit and any 

 of the dry material are carried into the entrance of 

 the material hose and by the same through the mix- 

 ing nozzle where the necessary water is added for the 

 hydration of the materials. A cross section of the 



loss of the binding power of the cement in transit is 

 absolutely avoided. The initial' set of the cement 

 takes place on the structure and not in the mortar box. 

 Another very important factor of the Cement- 

 rubber lined mixing nozzle is shown under Fig. 1, on Gun process is that only the proper amount of water 

 page 185 (April issue), and the working of the same for perfect hydration can be added, because all super- 

 is easily understood. The water supply is carried fluous water is expelled automatically by the force of 

 through a separate one-half-inch hose line and its 

 flow is regulated by the handwheel valve at the nozzle 

 end. The water pressure must be at least from 15 to 

 25 pounds higher than the air pressure used to obtain 



impact of the material at its place of deposit. 



If we consider that the air in the Cement-Gun 

 does not act as a plunger in forcing the material 

 through the delivery hose but carries the materials 



best results. by suspension and skin friction, we can easily under- 



The gun is also equipped with the necessary shut- stand that only a dry material can be successfully 

 off and by-pass valves, pressure gauge and is mounted conveyed by air pressure and that only a machine 

 on two wheels which allow its moving from place to shooting dry material can be self-cleaning and free 

 place like a cart. The weight of a gun is about 1,100 from clogging and excessive wear. 



pounds and the height of the charge opening is about 

 54 inches above the ground. 



An air compressor delivering about 40 cubic feet 

 of compressed air at 45 pounds pressure, which is 



For the lining of irrigation ditches it is often very equal to about 150 pounds free air per minute, is suffi- 

 advantageous to place the gun in the ditch and pro- cient for the ordinary working capacity of the gun 

 vide gravity chute for filling. 



The material hose is from 1 inch to 

 side diameter and may be of any length up to 300 feet 

 or even more. Of course, it is good economy to keep 



the hose line as short as possible, and rather move the 



of say \y 2 cubic yards of dry material per hour. A 

 inches in- larger volume of air at higher pressure will greatly 

 increase the capacity up to a maximum of about 3 

 cubic yards per hour. 



(Continued on page 217) 



