"An engineer should make briquettes of the differ ent classes of sand on his work, in order that he will be certain whether or not he is warranted in accepting sand with a slight excess of silt rather than a finer or poorly graded sand which comes well within the specifications as to silt.
"Construction See that the forms are built to the lines and according to the approved plans. See that the lumber is sound, and all wale joints are well spliced; that lumber, where toe-nailed, is efficiently nailed; that all forms are plumb ; that all form rods have washers under their heads and nuts; that they are taut when concreting is begun, and that they remain so during the progress of the work.
"Forms are designed for a certain number of vertical feet rise for a clay's concrete work. Find out how many vertical feet. If for any reason the concrete is changed from a dry concrete to a wet one, consider the number of feet rise permissible under the changed conditions. In this connection I wish to say that the keeping of forms plumb is the most difficult thing which devolves upon the engineer, the contractor, and their assistants. The building of plumb vertical walls can be obtained only when everybody on the work looks out for them. I have seen some very excellent concrete work done in different parts of the country where nearly all of the concrete walls were as much as 2 or 3 in. out of plumb.
"Inspectors should report to the assistant engineer any undue cutting of washers into the wood; also all form rods which have broken under the strain of the concrete. See that tongued-and-grooved dressed lumber is used where required.
"Use sized studs for all finished work. See that the forms are held tightly when beginning a day's work. If they are not, the load of the fresh concrete will push out the forms, causing not only lipping, but the mortar above will flow into the crack thus formed between the lagging and the old concrete, which will make a hole in the face work. See that heavy reinforcement is placed within the forms before the form tie-rods are placed, as these tie-rods frequently interfere with the placing of heavy reinforcement. Forms for finished work must be held together by tie-rods with coupling placed at least 3 in. from the finished face to permit of removal of all iron within 3 in. of the finished face. This is done in order to prevent rust stains. Forms may be held by wire on unfinished work.
"Have the contractor so lay out his work that he will reduce the walking over and the working-on on all settling concrete to a minimum. Allow the contractor departure from established lines on finished work, and 2-in. on unfinished work. (The latter may be in creased indefinitely, depending on the size and nature of the work, but as a general rule the forms should be within 2 in.) "Block Work. Soupy concrete—that is, concrete which contains about one more bucket of water than the concrete specified for mass work—should be used on block work. This will enable the moulders to bring out the details and arrises more strongly.
"Facing stone dust or grit and facing sand should all have all coarser material removed by screening; mesh is small enough for large blocks and large details; use %-in. mesh for fine work. Be careful, in passing upon the stone dust, that it does not contain a large percentage of rotten rock. All mud balls must be re moved for facing work. The backs of all blocks should have recess places in the back, covering practically one fifth of the area in the back, for the purpose of bonding with the mass. These recesses may be best obtained by placing wooden blocks, say, 6x6-in. or 8x8-in., in the concrete when first deposited, and removing same before final set.
"Cast all blocks with most important face down. All other showing faces should be cast vertical, or as near vertical as practicable. The back of the block— that is, that portion of the block which will not show in the structure—should always be moulded up, because the laitance or slime always rises to the surface, giving it not only a bad color, but a weak surface, and one which is certain to hair-crack. All blocks should be moulded in forms which are level—that is, which rest on a level platform—and great care should be taken by the inspector to see that the forms are stiff and do not bulge or distort under the concrete. If this is not done, the contractor will find it necessary to do a great amount of cutting, which in many cases will result in going through the mortar facing in order to get the block out of wind. All blocks should be left on their bottoms from two days to two weeks, depending on the size of the block, the nature of the cement, and the condition of the weather. If not, they will be liable to break in handling.