204-5.2 The unit of measurement for the bituminous material shall be the gallon or the ton, whichever is called for in the bid schedule. The gallonage or tonnage to be paid for shall be the number of gallons or tons of bituminous material used as ordered in the accepted work. Gallonage shall be determined by measuring the material at a temperature of 60° F., or by converting the gallonage measured at other temperatures to gallonage at 60° F. in accordance with A. S. T. M. Designation D-206 for asphalt materials, or with A. S. T. M. Designation D-633 for tar, or in accordance with appropriate formula or table for emulsified asphalt. BASIS OF PAYMENT 204-6.1 The quantities of base mixture and bituminous material determined, as provided in 5.1 and 5.2 above, shall be paid for at the respective contract unit prices per square yard in the bid schedule for base course and per gallon or per ton for bituminous material, which prices and payment shall constitute full compensation for preparing subbase or subgrade; for furnishing, handling, mixing, manipulating, and placing all materials; for all shaping, compacting, and rolling; for finishing; for improving unsatisfactory areas including remixing when necessary; for furnishing samples; for furnishing and sealing of scales; for furnishing the weigh house; for all labor, equipment, tools, and incidentals necessary to complete the item, except any prime coat or tack coat. Payment will be made under: Item P-204-6.1 Mixed in-place Base Course-per square yard. DESCRIPTION 205-1.1 This item shall consist of a base course composed of crushed stone or crushed slag, constructed on the prepared underlying course in accordance with these specifications and in conformity with the dimensions and typical cross section shown on the plans, and with the lines and grades established by the engineer. 205-2.1 MATERIALS AGGREGATE. The coarse aggregate and screenings shall be either crushed stone or crushed slag. The crushed stone shall consist of hard, durable particles or fragments of stone, free from an excess of flat, elongated, soft or disintegrated pieces, dirt or other objectionable matter, and shall have a percent of wear of not more than 45 at 500 revolutions as determined by A. A. S. H. O. Method T-96 (Los Angeles Rattler Test). The crushed slag shall be air-cooled blast furnace slag, and shall consist of angular fragments, reasonably uniform in density and quality, and reasonably free from thin, elongated, or soft pieces, dirt, and other objectionable matter. It shall weigh not less than sixtyfive (65) pounds per cubic foot, and shall have a percent of wear of not more than 45 at 500 revolutions as determined by A. A. S. H. O. Method T-96 (Los Angeles Rattler Test). The crushed aggregate shall not show evidence of disintegration, nor show a total loss greater than twelve (12) percent when subjected to five cycles of the sodium sulphate accelerated soundness test using A. A. S. H. O. Method T-104. Crushed stone and crushed slag for coarse aggregate and screenings shall meet the requirements for gradation given in Table 1, using A. A. S. H. O. Method T-27. CONSTRUCTION METHODS 205-3.1 OPERATION AT SOURCES OF SUPPLY. All work involved in clearing and stripping of quarries and pits and handling unsuitable material encountered shall be performed by the contractor at his own expense. The base material shall be obtained from sources that have been approved. The material shall be handled in a manner that a uniform and satisfactory product shall be secured. 205-3.2 EQUIPMENT. All equipment necessary for the proper construction of this work shall be on the project, in first-class working condition, and shall have been approved by the engineer before construction is permitted to start. The powered roller shall be of the three-wheeled type, weighing not less than ten (10) tons. The roller shall have a rear wheel compression of not less than 330 pounds per linear inch of tire width and shall be equipped with adjustable scrapers. The roller shall be maintained in good working condition and be operated by an experienced rollerman. Equipment for spreading and shaping shall consist of spreader boxes having strike-off templets or screeds, or consist of other approved spreading devices which will place the base aggregate or insulation material in uniform layer with a minimum of segregation. The crushing plant and the screening plant shall be designed, constructed, and operated and of such capacity so as to produce a base course material of the gradation and fractions required. Provision shall be made by the contractor for furnishing water at the site of the work by equipment of ample capacity and of such design as to assure proper application when required for compacting the insulation course. 205-3.3 PREPARING UNDERLYING COURSE. The underlying course shall be checked and accepted by the engineer before placing and spreading operations are started. Any ruts or soft, yielding places that appear by reason of improper drainage conditions, or hauling, or from any other cause, shall be corrected and rolled until firm before the base course is placed thereon. Grade control between the edges of the runways shall be by means of grade stakes, steel pins, or forms placed in lanes parallel to the center line of the runway, and at intervals sufficiently close that string lines or check boards may be placed between the stakes, pins, or forms. To protect the subbase and to insure proper drainage, the spreading of the base shall begin along the center line of the runway or taxiway on a crowned section or on the high side of the pavement with a one-way slope. 205-3.4 INSULATION COURSE. sand shall be spread uniformly upon the amount of not less than seventy-five (75) unless otherwise specified in the proposal. A layer of screenings or underlying course in the pounds per square yard The screenings or sand shall be spread by methods similar to those required for spreading coarse aggregate and if necessary shall be shaped by road machine to the required section and smoothness. The layer shall then be rolled and watered until firmly compacted. The sand gradation shall be such that from five (5) to ten (10) percent shall pass the No. 200 mesh sieve. 205-3.5 SPREADING COARSE AGGREGATE. When the prepared underlying course is the insulation course, it shall be checked and accepted by the engineer before placing and spreading operations are started. The coarse aggregate shall be spread uniformly and evenly upon the prepared course by the use of spreader boxes or other approved devices that shall spread the aggregate in the required amount so as to avoid or minimize the need for hand manipulation. Dumping from vehicles in piles or windrows so as to require rehandling will not be permitted. Hauling over the partly completed base course shall not be permitted. The surface of the aggregate shall be carefully trued up and all high or low spots remedied by removing or adding aggregates as may be required. The course shall be lightly rolled, after which the surface shall again be tested and trued up if necessary. This operation shall be repeated until the uniform smooth surface is secured which, when tested with a sixteen (16) foot straightedge, shall be found to be free from high and low places. The base course shall be constructed in a layer of not less than three (3) inches nor more than four (4) inches of compacted thickness. No segregation of large or fine particles will be allowed, and the coarse aggregate as spread shall be of uniform gradation with no pockets of fine materials. Coarse aggregate, unless otherwise permitted by the engineer, shall not be spread more than 2,000 square yards in advance of the rolling and application of screenings. 205-3.6 ROLLING. Immediately following the trueing of the spread coarse aggregate, it shall be compacted to the full width by rolling with a three-wheel power roller. Rolling shall progress gradually from the sides to the center of the lane under construction or from one side toward previously placed material by lapping uniformly each preceding rear-wheel track by one-half the width of such track, and shall continue until the entire area of the course has been rolled by the rear wheels. The rolling shall continue until the stone is thoroughly keyed, the interstices of the metal reduced to a minimum and creeping of the stone ahead of the roller no longer visible. The course shall not be rolled when the underlying course is soft or yielding or when the rolling causes a wavelike motion in the base course. When the rolling develops irregularities that exceed threeeighths (%) inch when tested with a sixteen (16) foot straightedge, the irregular surface shall be loosened and then refilled with the same kind of material as that used in constructing the course and again rolled as required above. 763591-48 Along places inaccessible to rollers, the base course material shall be tamped thoroughly with mechanical or hand tampers. Each hand tamper shall weigh not less than fifty (50) pounds and have a face area of not more than one hundred (100) square inches. 205-3.7 APPLYING SCREENINGS. After the coarse aggregate has been thoroughly keyed and set by the rolling described, screenings in an amount that will completely fill the interstices shall be applied gradually and uniformly over the surface. Rolling shall be continued while the screenings are being spread so that the jarring effect of the roller will cause them to settle into the voids of the coarse aggregate. The screenings shall not be dumped in piles on the coarse aggregate but shall be spread in thin layers. The roller used shall meet the requirements specified above and be equipped with a broom of an approved type. The screenings shall be applied at a uniform and slow rate so as to insure filling of all voids. Hand brooms, where necessary, shall be used to sweep the screenings into unfilled voids and to distribute them. The spreading and rolling and brooming of screenings shall be performed on sections not to exceed 2,000 square yards, and shall continue until no more screenings can be forced into the voids of the coarse aggregate. 205-3.8 SURFACE TEST. After the course is completely compacted, the surface shall be tested for smoothness and accuracy of grade and crown, and if any portions are found to lack the required smoothness or to fail in accuracy of grade or crown, such portions shall be scarified, reshaped, recompacted, and otherwise manipulated as the engineer may direct until the required smoothness and accuracy is obtained. The finished surface shall be such that it will not vary more than three-eighths (%) of an inch from the sixteen (16) foot straightedge applied to the surface parallel to the center line and at right angles. 205-3.9 RECONSTRUCTING MACADAM. Should the underlying course at any time become soft or churned up with the base course material or the shoulder material mixed with the base course material the contractor shall, without additional compensation, remove the mixture from the affected portion, reshape and compact the underlying course, and replace the removed section in accordance with the foregoing requirements. 205-3.10 THICKNESS. The thickness of the base course shall be determined by depth tests or cores taken at intervals in such manner that each test shall represent no more than 300 square yards. Where the base deficiency is more than one-half (2) inch, the contractor shall correct such areas by taking up the base material, removing and replacing with satisfactory materials properly laid, rolled, bonded, and finished in accordance with these specifications. The contractor shall replace at his expense the base material where borings are taken for test purposes. 205-3.11 MULTIPLE LAYERS. When it is necessary to construct the course in more than one layer to conform to the lines, grades, and cross-sections indicated on the plans, each layer shall be constructed as described above. |