125 



On Ni)vc'mber 27, 1920, in the presence of the Committee, the long pile was 

 pulled for examination. The upper half of the concrete was good except for a large 

 lailantx' hole about four feet from the to]). The lower halt ol the concrete was not in 

 good condition and in some spots could he kicked to pieces. In other spots there was a 

 thin shell of good concrete on the outside, while f)n the inside the material was like 

 mud. The whole lower 15 feet ot the casing was broken off without difficult}' with a 

 sledge hammer. On Wednesday, December 1, 1920, the shorter pile was jiulled and 

 the concrete was found in excellent cfindition. 



The results of this test cannot he considered conclusive, however, since not 

 enough piles were coated to show what the a\erage results would be. 



A large number of piles, reported to be about 2600, were protected during 1920 

 by this method at the dock f)f the California Wharf antl Warehouse Co. at Port Costa. 

 The length of the protection required was up to 28 feet, averaging about 15 to 18 feet. 

 The cost of this work was reported to be about 50 cents per lineal foot for materials 

 and SI. 50 per lineal foot to the contractor to cover labor and other costs and his 

 profit. The company employs an inspector to examine each finished coating very 

 carefully, using a hook on a pole below water line. Defects found above water can 

 be easily repaired. When defects are located below water, larger forms are used and a 

 new jacket is cast over the first one. Only meagre data respecting the performance 

 of this installation have been available to the Committee. 



The advantages of this process are: (1) the possibility of repairing damaged piles 

 in place, with little or no disturbance to the structure or interruption of business; 

 (2) the possibilit\' of coating piles at any stage of the tide; (3) rapidity of the work, and 

 (4) the relati\ely short portion of the pile requiring protection. The disadvantages of 

 the process are; (1) the danger of getting defective concrete, especially at the greater 

 depths; (2) the danger of getting the concrete thin on one side and thick on the other, 

 which is especially likely to happen if the pile is leaning or crooked; (3) the disturbance 

 of the mud caused by removing the bottom form, which may leave wood exposed below 

 the concrete, leaving it a question whether the holes thus formed will tend to fill up 

 with mud, or whether an eddy will form and keep them scoured out; (4) mud scour, 

 which may take place to a greater depth than provided for by penetration of the 

 shell, leaving wood exposed below the concrete; (5) the absence of adequate reinforce- 

 ment. The work must be done by a thoroughly skilled and responsible crew to insure 

 good results in any case. 



Several thousand piles have been treated by this process in the San P'rancisco 

 Bay region. Unfortunately, accurate data on the number of piles protected by this 

 method in its largest installations, the percentage of good results and the average life 

 obtained could not be secured. It is onh' lair to sa\', howe\-er, that since the earlier 

 days of the Committee work the examples of this process which have been examined 

 ha\-e indicated a considerably higher percentage of good results than did the experi- 

 ments of 1920. 



Xewsome-Squire Process 



This process, introduced in 1921, consists of a concrete protection for a timber 

 pile, constructed by placing the form, and then pouring the concrete simultaneously 

 with the driving of the pile. The impact of driving is thus utilized to secure thorough 

 compacting of the concrete. Insufficient time has elapsed to judge the effecti\eness 

 of the process. 



PRE-C.\ST TYPE 



Pre-cast concrete pile protections have been of two general forms. In the first 

 of these the reinforced concrete protective shell is cast, upon land, entireh- separate 



