That the concrete, gravel or crushed stone used is of the proper quality, the proper quantity used, and that it is placed and compacted so as to fill the spaces designated under and around the stone. The tendency of the workmen is to treat these details as unimportant and to slight the work.
After the curbing is set any spaces between it and the edge of the sidewalk are to be cleaned out, filled and trimmed with Portland cement mortar.
16. Rough Grading.—If plows and scrapers are used in the rough grading, see that they are not allowed to penetrate or to disturb the natural soil below the true grade, and to prevent this it is better to require that the plowing and scraping shall not approach nearer than one or two inches to the true grade.
If embankment or filling is necessary, the filling material must be deposited in regular layers not more than six inches deep and each layer must be well compacted by rolling or ramming before the next layer is applied.
17. Fine Grading.—The fine grading (with pick or mattock and shovel), to bring the sub-grade to the true grade and contour required, should be done with reasonable accuracy and care. Allowance must be made for compression under the roller, so that when completed the surface shall not vary more than half an inch below nor more than a quarter of an inch above the true grade, in order that room for the full thickness of concrete foundation may be provided, and no more. Humps, depressions and irregularities of the surface are to be avoided. The fine grading will be completed by thoroughly rolling or tamping the surface to make the soil firm and dense. On some soft or wet, clayey soils, excessive rolling may produce a plastic or “liver-like” condition and the rolling should be discontinued where such a tendency appears.
18. Work Incidental to Grading.—Where it is a part of the contractor’s work to reconstruct or readjust catch basins, manholes, covers, and other structures, he should be required to keep this work done well in advance of the laying of the concrete foundation. If this work is delayed until after the main body of the concrete is in place, leaving openings to be filled later, hurriedly and perhaps carelessly, it may result in weak patches in the concrete around these structures, where, in fact, the concrete should be strongest.
CONCRETE FOUNDATIONS
19. The concrete foundation of a pavement is a most important part of the work, and must not be slighted in any way.
20. Quality of Materials.—The quality of the materials used for making the concrete are fully described in the specifications, and they must be substantially and uniformly adhered to.
The Portland cement delivered on the street will presumably have been previously inspected and accepted by the engineer, but any change in the kind, or brand, or apparent quality of the cement delivered after the beginning of the work should not be permitted without the approval of the engineer. Barrels or bags of cement not plainly marked with the brand, or name of the manufacturer must be rejected. You will frequently make balls of stiff mortar from the cement and sand used (1 part cement, 2 parts sand) and set them aside for observation. If in eight hours these balls do not set up hard the fact should be promptly reported to the engineer.