APPENDIX B. 319 



As soon as concrete is deposited in the forms it shall be spread in layers not more 

 than 8 inches thick and be compacted by ramming. The engineer shall prescribe the 

 number of men to be employed on this part of the work, as the ramming must be thor- 

 ough. The rammers shall be of iron or steel, with flat rectangular faces 6 inches square, 

 weighing with the handle about 20 pounds each. When deficiency of moisture is 

 apparent after the ramming has been completed, water must be supplied by sprink- 

 ling, and all exposed surfaces of unfinished work must be kept constantly moist by 

 sprinkling, at short intervals, if so directed, until thoroughly set. 



The concrete above the lower miter-sill level must be built in blocks of the dimen- 

 sions shown on the drawings, arranged in regular courses for the full length of the wall. 

 Each horizontal course of blocks shall be of the same height throughout, and the 

 vertical joints shall be continuous. The ends of adjacent blocks and the surfaces of 

 consecutive courses shall be well bonded into each other. On those faces of the blocks 

 which are to be formed against dressed lumber, the contractor will be required to mark 

 out the joints between adjacent blocks, by dressed battens nailed against the inside 

 of the forms, the battens to be of dimensions approved by the Engineer. 



(Note. If the wall is to be built in monoliths of the full height, the following clause 

 may be substituted for the preceding: 



The concrete above the foundations shall be built in monoliths extending from 

 the foundation course to the top of the wall, provision being made for the proper bond- 

 ing of the adjacent blocks. The concreting shall be carried on in daytime only, but 

 work once commenced in a block must be prosecuted each succeeding day without inter- 

 ruption other than that caused by suspension of work for Sundays or legal holidays.) 



Whenever concrete is to be placed on a block or a layer that has set, all chipped 

 or broken edges shall be cut out, the surface shall be thoroughly brushed off and wetted, 

 and shall be covered with a grout of neat cement worked into the surface with brooms. 

 No concrete will be allowed to come into contact with a dry, dirty, or dusty surface. 



Whenever concreting is suspended for more than one hour on any block, course, 

 or layer, the outer edges shall be brought to a level, and where facing is used they shall 

 be carefully struck off with a trowel and a straight-edge before the cement has begun 

 to set. No uneven edges will be allowed, and the concrete must be kept approximately 

 level during the laying. Whenever work is thus suspended, the center of the last layer 

 shall be left as a ridge about 6 inches higher than the outsides, so as to provide a 

 bond for the next layer, and all the concrete in this layer, together with its facing, shall 

 be mixed with an additional amount of water, to prevent drying out. 



No concrete shall be laid in water except to stop leaks or springs, nor exposed to 

 the action of running water until thoroughly set. 



The use of slides or chutes for depositing concrete will not be permitted. 



No concrete shall be laid at night, unless specially ordered by the Engineer. 



39. Facing. All surfaces of the walls which will be visible after the work has been 

 completed, except the coping, together with all portions for a width of 2 feet lying imme- 



