123 



and alrt"atl\' altarki-il li\ liori-rs, inv wliiih tlH-\- afinrd i1k- (inl\- practical nu-ans whicli 

 has come to tlic kiiowied.nc of tlic ("oniniitlec. The forerunner of the present systems 

 was one of them. The one most used in the San Francisco Bay district is that employed 

 bv Mr. Frank ("amp. Mr. Alois Neuhert, a di\er and piling repair and construction 

 contractor of long experience, has also an interesting process. 



Bl.vck's P.\tent 



This was the forerunner of tiie present day sectional form |)ile jacket construction. 

 It was used from 1908 to 1913, the most important installation being of some 2000 in 

 large docks of the Standard Oil Company at Richmond. The concrete was poured 

 above water level in successively added sectional forms, as in the present day methods; 

 but the forms were of metal, each successive section being secured to the preceding 

 as it was added, and the forms were left in place after the operation was completed. 

 The method was thus much slower, less convenient and less adaptable than the later 

 modifications with hinged wooden quarter sections, and suffered from at least as 

 many shortcomings. The results were not on the whole promising. The Richmond 

 installation gave good service, but more than one-half of them were used over copper 

 sheathed piles beginning to show need of additional protection. Out of 300 installed 

 under normal conditions, for the State Harbor Commission, o\er 80 per cent have been 

 removed. The method is no longer actively promoted. 



("amp Pkocess 



This process of timber jjile protection is ])erha|)s the most t\pical method. It 

 consists in placing the concrete jacket in forms made in ,i-it. cylindrical sections, 

 about 20^2 inches in diameter, of tongued and groo\ed wood staves, bound with 

 angle iron hoops. Each 3-ft. section is di\ided into cjuarters, two quarters being 

 hinged together to make a half-c\linder. Tiie haUes are placed around the pile and 

 fastened together with iron lock-wedges to make the completed cylinder. 



The sequence of construction is as follows: The first 3-ft. section, which will 

 idtimately be the lowest piece of the form, is fastened around the pile. The lower end 

 of this section is pro\-ided with a special gasket which fits snugly against the pile, 

 sealing the bottom end of the form. The section is filled with concrete consisting of 

 one part cement, two of sand and three of pea gra\'el, and is then lowered by means of 

 cables until there is room to place the second form section. This is bolted to the first, 

 filled with concrete and the forms thus far filled are again lowered enough to allow 

 placing the next section. This continues until the entire form and the pouring of 

 concrete is completed, the bottom form having reached and penetrated the mud, the 

 top being as high as desired. In this way the concrete is all placed above water and 

 afterwards lowered to its final position. This feature avoids the difficulty of making 

 the form entirely watertight and of pumping it dry before placing the concrete. The 

 form is left in place about two days, and is then removed by pulling the iron lock- 

 wedges, all of which are attached to a chain running up the side. 



Under proper conditions, if the form is made reasonably tight and the concrete 

 properly mixed, the lowering operation should be accomplished with little or no salt 

 water getting into the mixture. If, howe\er, the mixture is too dry or the coarse 

 aggregate too large, it may drag on the pile surface while the form is being lowered 

 and open up pockets in the concrete. Leaking sea water is likely to fill these holes and 

 later become mixed in the concrete, giving poor results The process is likely to be 

 more successful on piles in shallow water than on piles in deep water. The mixture 



