diately compacted to conform with the surrounding area, all to be done at the expense of the contractor.

410-4.9 SURFACE COVERING.

After rolling is completed

as described, a surface covering of treated material shall be spread uniformly over the surface. An even distribution can be obtained by the use of wooden lutes. Only sufficient covering shall be used to fill the surface voids in the pavement. After spreading, the covering shall be thoroughly rolled. The furnishing, application, and rolling of the cover shall be included in the price bid per ton for the asphalt concrete surfacing.

410-4.10 JOINTS. The mixture at the joints shall comply with the surface requirements and present the same uniformity of texture, density, smoothness, etc., as other sections of the course. In the formation of all joints, provision shall be made for proper bond with the new surface for the full specified depth of the course. Joints may be formed by cutting back of the previous day's run so as to expose the full depth of the course, and the fresh mixture raked against the joint, and thoroughly rolled.

410-4.11

SHAPING EDGES. While the surface is being compacted and finished, the contractor shall trim the edges of the pavement neatly to line.

410-4.12 SURFACE TESTS. The finished surface shall not vary more than one-quarter (4) inch for the wearing course when tested with a sixteen (16) foot straightedge applied parallel with or at right angles to the centerline. Tests for conformity with the specified crown and grade shall be made by the contractor immediately after initial compression by powered rollers, and any variation shall be corrected by removing or adding materials and continuing the rolling. After the completion of final rolling, the smoothness of the course shall again be tested, and the humps or depressions exceeding the specified tolerances or that retain water on the surface shall be corrected by removing the defective work and replacing with new material, or by adding additional material as directed by the engineer at the expense of the contractor.

410-4.13 BITUMINOUS AND AGGREGATE MATERIAL CONTRACTOR'S RESPONSIBILITY. Samples of the bituminous and aggregate materials that the contractor proposes to use, together with a statement as to their source and character, must be submitted and approval obtained before use of such material begins. The contractor shall require the manufacturer or producer of the bituminous and aggregate materials to furnish material subject to this and all other pertinent requirements of the contract. Only those materials that have been demonstrated by service tests as satisfactory for the intended use will be acceptable.

For checking the adequacy of the equipment in use, inspecting the conditions and operation of the plant, for the verification of weights or proportions and character of materials and/or the determination and checking of temperatures being maintained in the preparation of

the mixtures, the engineer or his authorized representative shall have access at any time to all parts of the paving plant.

The contractor shall furnish vendor's certified test report for each carload or equivalent of asphalt cement shipped to the project. The report shall be delivered to the engineer before permission is granted for use of the material. The furnishing of the vendor's certified test report for the bituminous material shall not be interpreted as the basis for final acceptance. All such test reports shall be subject to verification by testing of samples of materials as received for use on the project.

410-4.14 FREIGHT AND WEIGH BILLS. Before the final estimate is allowed, the contractor shall file with the engineer receipted bills where railroad shipments are made, and certified weigh bills when materials are received in any other manner, of the bituminous and paving materials actually used in the construction covered by the contract. The contractor shall not remove bituminous material from the tank car or storage tank until the initial outage and temperature measurements have been taken, nor shall the car or tank be released until the final outage has been taken by the engineer.

Copies of all freight bills and weigh bills shall be furnished to the engineer during the progress of the work.

METHOD OF MEASUREMENT

410-5.1 The tonnage of asphalt concrete surface course to be paid for shall be the number of tons of bituminous mixture of the type as called for in the bïd schedule and used in the accepted work. The bituminous-treated material shall be weighed after mixing and no deduction shall be made for the weight of bituminous material in the mixture.

410-5.2

The bituminous material and other ingredients shall not be paid for separately but shall be included in the price bid for surface course above, and shall be considered incidental to the price for this item.

BASIS OF PAYMENT

410-6.1 The quantities of asphalt concrete surface mixture, determined as provided in 5.1 and 5.2 above, shall be paid for at the contract unit price per ton in the bid schedule for surface course, which price and payment shall constitute full compensation for preparing base; for furnishing, handling, mixing, manipulating, and placing all materials; for all shaping, compacting, and rolling; for finishing; for improving unsatisfactory areas; for reconditioning base and shoulders; for furnishing and applying surface cover; 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 or tack coat.

Payment will be made under:

Item P-410-6.1 Asphalt Concrete Surface Course-per ton.

ITEM P-411

SURFACE TREATMENT WITH BLENDED

NATURAL LIMESTONE AND SAND ASPHALT MIXTURE

411-1.1

(Central Plant-Cold Laid)

DESCRIPTION

This item shall consist of a surface treatment composed of natural asphaltic limestone and sand asphalt mixture, mixed in a central plant, and laid cold and placed on a prepared underlying course in accordance with these specifications and in conformity with the dimensions and typical cross section shown on the plans, and with lines and grades established by the engineer.

MATERIALS

411-2.1 AGGREGATES. The sand shall be sound, tough, and durable and be obtained from approved sources. The sand shall be free from vegetable matter, lumps or balls of clay, adherent films of clay, or other matter that will prevent thorough coating with bituminous material. The sand shall be so graded that not more than five (5) percent will be retained on a No. 4 mesh sieve, and not more than twenty-five (25) percent will pass a No. 40 mesh sieve.

The asphaltic limestone shall be uniform and well-graded, and shall contain not less than four (4) percent of native asphalt. It shall be so crushed that not more than ten (10) percent will be retained on a one-half (1⁄2) inch sieve.

Approval of the sources of supply of the mineral aggregates shall be obtained from the engineer prior to the delivery of the surface treatment material, and samples shall be submitted when requested by the engineer.

411-2.2 BITUMINOUS MATERIAL. The asphaltic flux shall consist of an asphalt cement meeting the requirements of A. A. S. H. O. Specification M-20. The penetration of the asphalt cement shall be between 150 and 200.

411-2.3 LIQUEFIER.

The liquefier shall conform to the requirements of A. A. S. H. O. Specifications M-83. The grade of liquefier shall be the light grade.

CONSTRUCTION METHODS

411-3.1 WEATHER AND

TEMPERATURE LIMITA

TIONS. The surface treatment shall be constructed only when the surface is dry, when the atmospheric temperature is above 45° F., and

when the weather is not foggy or rainy. The temperature requirement may be waived, but only when so directed by the engineer.

411-3.2 EQUIPMENT. (a) General. All methods employed in performing the work and all equipment, tools, other plant and machinery used for handling materials and executing any part of the work shall be subject to the approval of the engineer before the work is started, and whenever found unsatisfactory shall be changed and improved as required. All equipment, tools, machinery, and plant used must be maintained in a satisfactory working condition.

(b) Mixing Plant. The mixing plant used by the producer in the preparation of the bituminous mixture shall comply with the following requirements:

The drier, if necessary, shall be suitably designed to heat and dry the aggregate to specification requirements and to continuously agitate the aggregate during heating. The drier shall be capable of preparing aggregate to the full rated capacity of the paving plant to meet the specification requirement. A dial thermometer or other thermometric instrument shall be so placed in the bin over the mixer as to automatically register the temperature of the heated aggregate before it enters the mixer. The dial or other indicator shall be plainly visible from the mixing platform.

The combined aggregate shall be bypassed around any screen on the plant having openings smaller than five-eighths (%) inch. The plant shall have storage bins, protected from the weather, of sufficient capacity to furnish the necessary amounts of all aggregates when operating at the maximum rated capacity of the plant.

The plant shall have batch weighing of mineral aggregates and asphalt cement. This equipment shall be constructed with devices that will permit easy readjustment of any working part, such that it will function properly and accurately. The aggregate weighing device shall be so constructed and operated that the correct amount of each aggregate is introduced into the mixer with an accuracy that will meet the job tolerances specified.

The asphalt weighing device shall be so constructed and operated that the correct amount of asphalt is introduced into the mixer with an accuracy that will meet the job tolerance. The dial scales or other weighing device shall be of an approved type.

The mixer shall be a twin pug-mill mixer of sufficient size to maintain thorough, uniform mixing at the rated plant capacity.

The plant shall be equipped with positive means to govern the time of mixing and to maintain it constant unless changed by order of the engineer. The time of mixing shall be considered as the interval between the time the bituminous material is spread on the aggregate and the time the same aggregate leaves the mixing unit.

(c) Placing Equipment. Equipment for spreading, shaping, and finishing shall consist of an approved self-contained power machine operating in such a manner that no supplemental spreading,

763591°-48-19

shaping, or finishing will be required to provide a surface which will comply with the requirements for smoothness contained herein.

The motor grader shall be a modern unit, weighing not less than five (5) tons, and equipped with a mould board of at least twelve (12) feet in length. The grader shall be in good condition with the joints and connections, especially on the mould board and controls, tight and free from lost motion.

(d) Rolling Equipment. Rollers shall be suitably designed for the construction of bituminous surfaces. The rollers shall be self-propelled tandem and three-wheel type rollers weighing not less than eight (8) tons. The wheels on the rollers shall be equipped with adjustable scrapers which shall be used when necessary to clean the wheel surface. Rollers shall also be equipped with tanks and sprinkling apparatus which shall be used to keep the wheels wet and prevent the surfacing material from sticking.

The pneumatic roller shall consist of pneumatic tires arranged in a manner so as to provide a satisfactory compacting unit. The roller shall have an effective rolling width of at least sixty (60) inches, and shall give a compression of at least 275 pounds per inch of width of tread when fully loaded. The tires shall be uniformly inflated. The roller and the operating power unit shall meet the approval of the engineer.

The sand

411-3.3 PREPARATION OF AGGREGATES. shall be dried, if necessary, but shall not be heated over 200° F., and shall not contain more than two (2) percent moisture when placed in the mixer. The asphaltic limestone shall not be heated. The sand and the asphaltic limestone shall be placed in the bins at the paving plant and combined in the correct proportions when drawn from the bins for mixing. When possible, the sand shall be allowed to cool before mixing.

411-3.4 PREPARATION OF BITUMINOUS MIXTURE. Before being delivered to the runway, the aggregates shall be mixed with the bituminous material at a central mixing plant. The aggregates prepared, as prescribed above, shall be accurately measured and conveyed into the mixer in the proportionate amounts of each material required to meet the specified requirements. The amount of sand to be used in the mixture may be varied from twenty-five (25) to fifty (50) percent by weight. The exact amount shall be as stated in the proposal.

The bituminous material shall be stored in tanks of suitable capacity, and so located that the asphalt can be conveyed into the batch-weighing device.

The liquefier may be combined with the asphalt cement before shipment from the refinery, or may be introduced into the mixture at the central mixing plant. In either case, the amount of liquefier shall be between fifteen (15) and twenty (20) percent by weight of the asphalt cement used or added at the mixer.