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Setting the Blocks

street, block, joints and set

SETTING THE BLOCKS. In placing the blocks, the work man should stand upon the finished work, that the sand cushion may not be disturbed; but he usually stands on the sand cushion, the blocks being piled on the sand bed behind the paver. The workman with the pointed end of the hammer shown in Fig. 140, excavates a hole, if need be, into which to set the block.

To secure the proper form to the surface of the pavement, a chalk line is made upon each curb or a string is stretched in each gutter to indicate the top of the blocks, and a row of blocks 20 to 25 feet apart is set in the center of the street with their tops to grade, as determined by measuring down from a string stretched from curb to curb. If the street is wide, one or more rows of blocks are placed between the curb and the crown. Ordinarily the sur face of the pavement is brought to grade between the guide blocks with the unaided eye; but in the best work, a straight edge or string is placed parallel to the line of the street on the guide blocks, by which to grade the surface, and between these lines the blocks are brought to the surface indicated by a straight edge parallel to the line of the street resting upon the pavement already completed.

The blocks should be set with their long dimension across the street, except at street intersections; and should be placed in straight rows with as close joints as possible. Each course should be formed of blocks of uniform width and depth: and the bond should be approximately half the length of a block, or at least 3 inches. As the blocks are of uneven lengths, the securing of the proper bond will require careful attention. The paver is instructed to secure thin joints, and consequently has a tendency to set the block with the larger end up; but when set in this way the block will surely sink under traffic. Placing the large end of the block down makes a wide joint, which is objectionable if the joints are to be filled only with sand and pebbles (see 832), but is no serious objection if the joints are to be filled with hydraulic-cement grout (see 832).

The courses at street intersections are arranged substantially as in brick pavements (see 768). The work should progress up grade and from the gutter towards the crown, so that the blocks may have no tendency to settle away from each other and thus increase the width of the joints.