135 



angle iron luiops and by removalile exterior hoops of round bars, spaced several feet 

 apart. The interior hoops are bolted, while the exterior hoops are locked with wedge- 

 pins all connected to a chain running up the side of the form. When the form is com- 

 pleted it is lifted and clri\en into position with a modified pile dri\er, the "hammer" 

 being built of large timbers, having a dri\ing face several feet square. When the form 

 has been driwn to refusal the water is pumped out and the mud removed with a small 

 orange-peel bucket. The bottom excavation is then continued by hand down to 

 hardpan. The interior hoops are then removed and the concrete poured. After allowing 

 sufficient time for the concrete to set, the outer hoops are removed by pulling the wedge- 

 pins. The stave pieces can then be loosened and pulled and re-assembled for further 

 use. These serve for several piers before being discarded. 



SPKCIFK ATIONS FOR CONCRETE IN MARINE STRUCTIIRES, 

 WITH OUTLINE OF PRACTICE 



The treatment of this subject has been undertaken by the Committee, not in 

 competition with existing able discussions of the general subject of concrete, but from a 

 conviction that this specific phase, appropriate to the attention of this Committee, 

 has not been adequately considered in previous discussions. The material presented 

 has been prepared by a special sub-committee consisting of H. J. Brunnier, Consulting 

 Structural Engineer, San Franciscfj, and H. E. Squire, Assistant Engineer, Board of 

 State Harbor Commissioners, San Francisco. 



This Outline of Practice with Specifications is intended to cover onlj' the phases 

 of design and construction which affect the durability of concrete exposed to sea 

 water and to present practical working specifications for this class of work. Its applica- 

 tion is further limited to Pacific Coast conditions, which are fret' from extreme tem- 

 peratures and ice action. 



The general retiuirenicnts lor materials antl workmanship are presented in the 

 form of a working specification. This is followed by a brief discussion of the application 

 of the specifications in the design and construction of different types of structures 

 under ^■arying conditions of exposure. The specifications must be read in the light 

 of the s]iecific application to which the\- are limited, as thus discussed. 



