278 



THE IRRIGATION AGE. 



SHOOTING CEMENT LININGS INTO DITCHES 



By CARL WEBER. C. E. 



President Cement-Gun Construction Company, Chicago 

 (Continued from May issue) 



THE mortar lining applied by 

 the Cement-Gun process 

 differs greatly from any hand- 

 applied or poured material and 

 shows characteristics all of its 

 own. Numerous comparative 

 tests have been made to com- 

 pare the quantities of "Gunite" 

 with other materials of the same 

 composition and it has been 

 found that in every instance 

 Gunite is vastly superior. 

 Tested for tension and com- 

 pression, the strength of Gunite 

 is from 1.5 to 4 times greater 

 than the best hand-applied 

 mortars. Gunite is waterproof 

 and adheres to hard surfaces 

 with utmost tenacity. Steel 

 girders have been coated with 

 Gunite and after the coating 

 was removed by bending and 

 dropping the steel members it 

 was found that a film of cement 

 still remained on the steel, pro- 

 tecting the same effectively 

 against corrosion. 



These qualities make Gunite 

 very desirable for encasing of 

 steel structures for rust pre- 

 vention and numerous large 

 and small railroad bridges have 



been protected in this manner. For the fireproofing 

 of the structural steel in large buildings, Gunite has 

 also found wide adoption and amongst others, the steel 

 work of the Woolworth Building in New York (the 

 largest skyscraper in existence) has received Gunite 

 encasing. 



Another large field for Gunite work is the repair 

 of old disintegrating stone and concrete walls, etc. 

 Large sea walls, bridge foundations and similar struc- 

 tures have been successfully restored even after decay 

 had gone so far as to endanger the safety of the work. 

 Figs. 6 and 7 illustrate the method which was used 

 for the repair of the piers for a bridge of the Chicago 

 & Western Indiana R. R. Co. over the Chicago drain- 

 age canal. The piers were built of limestone blocks 

 and the depth of deterioration varied from 2 inches 

 deep to the depth of 16 inches. 



The stone work was thoroughly cleaned, all loose 

 and decayed surfaces were carefully removed and the 

 hollows were filled with Gunite to within about 2 

 inches from the original surface. Then a^ strong wire 

 mesh was evenly stretched and securely fastened over 

 the entire pier and the last 2 inches of Gunite were 

 applied over and enveloping this wire mesh as 

 shown in Fig. 7. The wire mesh reinforcement is 

 not always necessary and where the disintegration 

 is of a more uniform depth or where only a thin 

 coating is applied over a rigid surface not subject 

 to vibrations the wire mesh may be omitted. 



Another most successful use of Gunite has been 



Fig. 6 Repairing piers of a bridge on the Chicago & 

 Western Indiana Railroad Company with a cement gun. . 



found in the waterproofing of 

 large and small water reser- 

 voirs. As stated before, Gunite 

 is waterproof on account of its 

 density and no compounds, 

 soap, paraffin or other mixtures 

 are ever used. Large concrete 

 reservoirs which could not be 

 considered safe on account of 

 excessive seepage have been 

 treated with the Cement-Gun 

 and in a reservoir in San Fran- 

 cisco a Gunite application of 

 from only l / inch to l / 2 inch 

 thickness was found sufficient 

 to make the same absolutely 

 safe against a water pressure 

 of about 27 feet depth. The 

 subject of waterproofing of 

 reservoirs, etc., is of so great 

 an importance to irrigation 

 interests that I decided to give 

 a full account of the same in 

 a later part of this paper and 

 therefore will only mention it 

 here briefly. Just at this time 

 we are executing extremely 

 interesting work of this kind 

 for a large water power plant 

 in Illinois and I will give a 

 description of the same with 

 illustrations in a later issue of 

 IRRIGATION AGE. 



Before giving a detailed description of successful 

 work for the lining of irrigation canals, I want to call 

 again special attention to the density of Gunite, which 

 is best illustrated by the fact that the weight of Gunite 

 is about 18 to 20% more than the best concrete made 

 in the usual way. A cubic foot of Gunite made of a 

 1 to 3 l / 2 mixture of Portland cement and Torpedo 

 sand weighed 153.8 Ibs., while a cubic foot of the 

 same material mixed by hand and tamped in place 

 in the ordinary manner weighed 136.3 Ibs. This con- 

 clusively proves that the difference of 17.5 Ibs. repre- 

 sents voids in the handmade concrete and that it takes 

 more cement and sand to produce a cubic foot of 

 Gunite. This, of course, must be considered in 

 planning for Gunite work and therefore considerable 

 thinner linings are made if Gunite is used. For the 

 lining of irrigation ditches a Gunite slope lining iy 2 

 to 2 inches thick is usually sufficient, while for bottom 

 linings a slightly increased thickness is often advisable. 

 Another important factor is the ease with which 

 a Gunite lining can be reinforced to withstand shrink- 

 age and expansion and to impart a high degree of 

 elasticity, which is of greatest value in canal protection. 

 Gunite linings, if properly reinforced, do not need any 

 expansion joints and all danger of weakness of the 

 lining due to these joints is entirely avoided. 



As reinforcing material, a wire mesh of required 

 strength is most conveniently used. The same is 

 usually placed in the center line of the protective 



