Old stone foundation will be measured in square yards, in place after completion. The contract price includes the cost of handling and cleaning the stone, supplying and placing the bed of sand, setting and ramming the stone, supplying the materials for, making and placing the mortar in the joints and watering the street while the mortar is setting. Where stone is procured from other streets, or from storage yards, the Contractor will be required to load, haul and unload them, and will be allowed for this service a price of ... cents per cubic yard for loading and unloading, plus ... cents per cubic yard for each one-half mile, or fraction thereof, over which they are hauled by the nearest practicable route, the measurement to be made after the stone is set in the street, without deduction for joints.
40. Broken Stone Foundation.—The sub-grade for broken stone foundation shall be prepared as specified in Section 26, except that the rolling may be omitted at the option of the Contractor. The broken or crushed stone shall be of hard, durable stone. The foundation shall have an aggregate thickness of ... inches and shall be constructed in two courses, as follows:
The broken stone used in the first course shall be of such size that it will all pass through a screen having openings three (3) inches in diameter, and will all be retained on a screen having openings one (1) inch in diameter. This stone shall be evenly spread over the sub-grade to such a thickness that after being thoroughly consolidated by rolling, its upper surface shall be three-fourths inch below, and parallel to the surface of the foundation when completed. It shall then be rolled with a road-roller weighing not less than ten (10) tons until the stone is thoroughly compacted.
The second course, composed of screenings, all of which shall have passed through a screen with openings one inch in diameter, shall then be spread over the first course and well raked into the voids of the first course. It shall then be thoroughly wetted, and shall be rolled with the ten-ton roller until the fine stone is driven into the interstices of the first course and the whole thoroughly consolidated, the wetting being repeated while the rolling continues. Additional screenings shall be added and rolled in where necessary to bring the surface to the proper elevation. When completed, the top surface of the foundation shall be ... inches below, and parallel to the pavement datum. No part of the upper surface of the completed foundation shall project more than one-fourth (¼) inch above, nor shall it be more than one-half (½) inch below the grade and contour above specified.
Gravel of a quality satisfactory to the Engineer may with his written consent be substituted for broken stone. If of assorted sizes, such as will compress into a mass having not more than thirty (30) per cent. of voids, the foundation may be constructed in a single layer, graded, watered and rolled, as prescribed above for broken stone.[[14]]
41. Measurement.—Broken stone and gravel foundation will be measured and computed by the cubic yard in the street as completed, without any allowance for consolidation by the roller or for settlement into the sub-grade, the thickness being taken as ... inches. The contract price for it shall cover the cost of supplying the material, placing it on the street, and grading, watering and rolling it.
SHEET ASPHALT PAVEMENT
Note.—A number of distinct varieties of asphalt are now used for asphalt pavements, either alone or mixed. These different varieties differ from each other quite widely in their physical and chemical properties. Thus, in the form called “refined asphalt” some of their properties are shown by the following table, the data for which is taken from the second edition of Richardson’s “The Modern Asphalt Pavement.”
| COMPARATIVE PROPERTIES OF DIFFERENT REFINED ASPHALTS | |||||
|---|---|---|---|---|---|
| Trinidad, average | Bermudez, average of two samples | Maracaibo, average of six samples | Calif. “D” grade, average of two samples | Gilsonite, average of two samples | |
| Softens, degrees F. | 180 | 165 | 225 | 132 | 280 |
| Flows, degrees F. | 190 | 175 | 236 | 151 | 300 |
| Penetration at 78° F. | 7 | 24 | 21 | 48 | 0 |
| Loss, heated to 325° for 7 hours, %. | 1.1 | 3.7 | 3.2 | 1.7 | 1.6 |
| Loss, heated to 400° for 7 hours, %. | 4.0 | 8.8 | 5.5 | 7.1 | 2.6 |
| Bitumen soluble in CS2. | 56.5 | 95.5 | 93.9 | 99.3 | 99.4 |
| Inorganic, other than bitumen. | 36.5 | 2.2 | 2.9 | 0.3 | 0.5 |
| Bitumen soluble in naphtha. | 35.6 | 65.6 | 51.1 | 69.6 | 47.2 |
| Bitumen sol. in carbon tetra-chloride. | 98.7 | 99.0 | 93.2 | 95.7 | 99.8 |
| Fixed carbon. | 10.8 | 13.7 | 17.2 | 17.6 | 13.2 |
The practice has been heretofore, and is at the present time, to attempt to make specifications for asphalt pavements broad enough to include all the various varieties of asphalts, under general requirements which shall admit these, and any new varieties that may appear on the market suitable for the purpose, the object being to permit a wide range of competition. This makes it exceedingly difficult if not impossible to frame specifications that shall be sufficiently explicit and at the same time sufficiently broad to admit these several differing materials. This practice has been adhered to in these specifications, though in this respect they are far from satisfactory to the author. So long as it continues to be the policy of cities to admit these various varieties of bitumen under the same general requirements for crude and refined material, such objectionable specifications cannot be avoided. Even with the great latitude now provided they exclude some materials with which good pavements have been made.