(a) The aggregate, water when required, and emulsified asphalt shall be mixed in a stationary pugmill or dryer drum plant capable of producing a uniformly mixed product. The plant shall be equipped with weighing, volumetric or other gauging equipment capable of providing accurate control of the materials entering the mixer. For continuous mixing plants and dryer drum plants, the controls for aggregate feed shall be interlocked with the asphalt emulsion controls and water controls to insure uniform introduction of the various materials into the mixer. Water when required, should enter the mixer prior to the introduction of the asphalt emulsion. The materials shall be mixed until all particles are uniformily coated. The resulting mixture shall have an uniform color and an even distribution of coarse and fine particles. At time of compaction the total liquid content (emulsion and water) shall be ± 2 percentage points from the optimum liquid content as determined by the Engineer. (b) Equipment for handling emulsified asphalt shall conform to the applicable requirements of AASHTO M 156. When emulsified asphalt is metered into the mixing unit, a direct couple shall be provided between the aggregate feed and the liquid feed, and positive displacement pumps shall be used to control the flow of emulsified asphalt. (c) Vehicles used for hauling bituminous mixtures shall have tight, clean, and smooth metal beds which have been thinly coated with an approved material to prevent the mixture from adhering to the beds. 302.06 Placing and Compaction. The placing shall commence at the point or points fartherest from the mixing plant and progress toward the plant, unless otherwise ordered by the Engineer. Hauling over material already placed will not be permitted until the material has been compacted in the manner specified. The mixture shall be placed in payment lanes of such width as to hold to a practical minimum the number of longitudinal joints required. The longitudinal joints in successive layers shall offset those in the layer immediately below by at least 6 inches. Longitudinal joints will be permitted in the top or final layer at the centerline of the pavement if the road comprises only two lanes of width, and/or at the traffic and auxiliary lane lines and at points of change in the designated cross-section slopes of the finished surface if the roadway comprises more than two lanes in width. Longitudinal paver spread joints will be permitted at intermediate locations of the traffic lanes of the top layer provided such intermediate joints are formed prior to rolling and are shaped and compacted while the bituminous mixture is still workable. For the initial and intermediate layers the bituminous mixture shall be placed either by paving machine or base paver at the contractor's option. For the final layer spreading equipment shall conform to subsection 401.09 and in addition shall be equipped with automatic screed controls with sensors for either side of the paver, which will control the placing of the mixture to specified transverse slope and specified longitudinal grade. The sensing device shall be adaptable to picking up grade information from a string-line or wire, rail, ski or adjacent strip of payment. The traverse slope controller shall be capable of maintaining the screed at the desired slope within plus or minus 0.1 percent. In the event of failure of automatic controls the Contractor will be permitted to finish the shift, but not to exceed 4 hours, using manual controls, but he will not be permitted to resume operations until the automatic controls are repaired. Manual operation will be permitted in the construction of irregularly shaped or minor areas. After the bituminous mixture has been spread, struck off and surface irregularities adjusted, and when the mixture is in the proper condition such that rolling does not cause undue displacement, cracking or shoving, the material shall be uniformly compacted by rolling. The number, weight, and type of rollers furnished shall be sufficient to obtain the required compaction while the mixture is in a workable condition. Not more than one pass may be made with a vibratory roller with the vibration mechanism operating. Tire pressure for pneumatictired rollers shall not exceed 40 psi. Unless otherwise directed, rolling shall begin at the sides and proceed longitudinally parallel to the road center line, each trip overlapping one-half the roller width, gradually progressing to the crown of the road. On super-elevated curves the rolling shall begin at the low side and progress to the high side by overlapping of longitudinal trips parallel to the center line. Rollers shall move at a uniform speed with the drive roll or wheels nearest the spreader. Rolling shall be continued until all roller marks are eliminated. Undue displacement occurring as a result of the reversing of the direction of a roller, or from other causes, shall be corrected at once by the use of rakes and addition of fresh mixture when required. Care shall be exercised in rolling not to displace the line and grade of the edges of the bituminous mixture. When directed by the Engineer, the Contractor shall develop roller patterns as set forth under Section 212. The surfaces of Gradings A, B, and C inclusive shall be allowed to cure for a period of not less than 10 days before sealing under Section 409, unless a shorter period is approved in writing by the Engineer. During this period, and until the seal is placed, the surface shall be maintained and kept free of corrugations. Any holes that develop shall be patched with bituminous and blotter materials as directed. All excess blotter material, dirt or other objectionable materials shall be removed prior to placing the seal coat. 302.06 Acceptance Sampling and testing will be in accordance with Subsections 401.21, 401.22 and 401.24. 302.07 Surface tolerance shall be in accordance with subsection 401.23 except that the variation of the surface from the testing edge of the straight edge shall, at no point, exceed 3/8 inch. Method of Measurement 302.08 Emulsified asphalt base course will be measured as prescribed in Subsection 401.25. Basis of Payment 302.09 The accepted quantities of emulsified asphalt base course measured as provided above, will be paid for at the contract unit price per ton for the bituminous base mixture and if included in the bid schedule as a pay item, per ton or gallon for the bituminous material complete in place, which prices and payment will be full compensation for the work of this section, except that pay factors will be applied to the contract unit prices in accordance with subsection 401.26. 303.01 This work shall consist of furnishing, placing and compacting a crushed gravel or crushed stone course on a prepared roadbed in accordance with these specifications and in reasonably close conformity with the lines, grades, thickness, and typical cross section shown on the plans or established by the Engineer. Materials 303.02 Crushed Aggregate. Aggregate shall consist of hard, durable particles or fragments of stone or gravel crushed to the size and of the quality requirements for crushed aggregate materials normally used locally in the construction and maintenance of highways by Federal, State or County agencies. Unless otherwise specified, the aggregates shall have a maximum size of 1 inch, shall be uniformly graded from coarse to fine and shall be free of vegetable matter and clay balls. Aggregates will be accepted by certification furnished by the Contractor in accordance with Subsection 106.03. The certificate of compliance shall state whose specifications the aggregates will conform to and shall include the quality and gradation requirements applicable thereto. The Engineer may conduct quality control reviews to determine the reliability of the certifications. If the reviews indicate that the certifications are not reliable, acceptance by certification will be discontinued. Materials furnished will be accepted or rejected in accordance with subsection 106.08 and subsequent materials furnished will be sampled, tested and accepted prior to incorporation into the work. All costs to the Government for sampling and testing may be charged against the Contractor and may be deducted from the payment for the work. Construction Requirements 303.03 Preparation of Roadbed. The roadbed, including shoulders, shall be constructed, prepared and finished as provided under Section 208. 303.04 Placing. The material shall be placed on the prepared roadbed in layers of the thickness shown on the plans. When more than one layer is required, each layer shall be shaped and compacted before the succeeding layer is placed. Placing shall be from vehicles equipped to distribute the material in a uniform layer or windrow. The layer or windrow shall be such size that when spread and compacted, the layer shall have the required thickness. When hauling is done over previously placed material, hauling equipment shall be routed as uniformly as possible over the entire width of previously constructed layers. 303.05 Mixing and Spreading. Each course placed shall be mixed to its full depth by means of power graders, traveling mixers or other approved mixing equipment. During the mixing, water shall be added in the amount mecessary to provide the optimum moisture content for compaction. When mixed, the material shall be spread smoothly to a uniform thickness, or in the case of the top course, to the cross section shown on the plans. Spreading shall be completed within 24 hours after mixing. 303.06 Compacting. Immediately following final spreading and smoothing, each layer shall be compacted full width by means of compacting equipment meeting the requirements of Section 212. Each 150 cubic yards of material placed shall receive at least one hour of continuous rolling. The Engineer may adjust the compactive time when approved rollers or compactors other than those specified under subsection 212.02 are furnished by the Contractor. Rolling shall progress gradually from the side to the center, parallel with the centerline of the road, and shall continue until all the surface has been rolled. Any irregularities or depressions that develop shall be corrected in a manner approved by the Engineer. Along curbs, headers, and walls, and at all places not accessible to the roller, the material shall be compacted with mechanical tampers. 303.07 Thickness Requirements. The thickness of the completed course shall not vary more than 1⁄2 inch from the thickness shown on the plans. 303.08 Surface Requirements. When directed by the Engineer, the surface shall be tested with a 10-foot straightedge furnished and operated by the Contractor. Any areas where the surface variation exceeds 1⁄2 inch in 10 feet shall be reworked until the variation falls within this limit. Method of Measurement 303.09 The quantity to be paid for will be the number of cubic yards measured in the hauling vehicle at the point of delivery, or tons of material placed, compacted and accepted in the completed course. Basis of Payment 303.10 The quantities, determined as provided above, will be paid for at the contract unit price per unit of measurement for the pay item listed below that is shown in the bid schedule, which price and payment will be full compensation for furnishing and placing all materials, including all labor, equipment, tools, and incidentals necessary to complete the work prescribed in this section. Water will be paid for as provided under Section 207. Payment will be made under: Pay item 303(1) Crushed aggregate. 303(2) Crushed aggregate. Pay unit Section 304.-AGGREGATE BASE AND SUB-BASE COURSES Description 304.01 This work shall consist of furnishing and placing one or more courses of aggregate, including additives if required, in accordance with these specifications and in reasonably close conformity with the lines, grades, thickness and typical cross sections shown on the plans or established by the Engineer. Materials 304.02 Aggregate. The aggregates for non-treated base and subbase shall meet the requirements of subsection 703.06. Aggregates for calcium chloride and hydrated lime stabilization shall meet the requirements of subsections 703.06 or 703.18. The aggregates for salt stabilization shall meet the requirements of subsection 703.19. When the stationary plant method (a) is used, the aggregate will be tested for acceptance immediately following mixing based on samples taken from the pug mill output. When the travel plant method (b) or the roadmix method (c) is used, the aggregate will be tested for acceptance based on samples taken from the windrow or roadway after final blending or at the point of production, as specified in the special provisions. 304.03 Chemical Additives. Chemical additives shall meet the requirements of the following subsections: Calcium chloride 712.02 712.02 712.03 304.04 Acceptance Sampling and Testing of Aggregate Base or Subbase Course (Gradation). The special provisions will specify: 1. Acceptance sampling frequency 2. Point of acceptance sampling. 3. Lot size. Random acceptance samples will be taken from each lot in accordance with subsection 106.03. If these samples, when tested, indicate that the lot contains no defective material, the lot will be accepted at the full contract price. If any test indicates that the lot contains defective material, the lot will be evaluated in accordance with Table 304.01. If the lot fails to qualify for at least a 0.85 pay factor in accordance with Table 304.01, the Engineer may reject the lot. If the Engineer allows the material to remain in place, it will be paid for at a pay factor of 0.70. The contractor may voluntarily elect to remove any defective lot and replace it with nondefective material to avoid a pay factor of less than 1.00. Any such new material will be sampled and accepted in accordance with this subsection. In addition to the random acceptance samples taken from each lot, the Engineer may sample and reject material which appears to be defective. Such rejected material shall not be used in the work. The results of tests run on rejected material will not be included with the lot acceptance tests. TABLE 304-1 Pay Factors for Aggregate Gradation of Crushed Aggregate Base Course and Subbase D - The allowable deviation in percent from the target values. (From Table 703-3.) - The difference between the highest and lowest values of the test results from a given lot. R - (Range) A lot must meet criteria for both the deviation of the mean and the maximum allowable range at a given pay level for the aggregates and bitumen content. Only the lowest single pay factor as determined from the table above, will be used in computing reduced payment for the lot. Construction Requirements 304.05 Preparation of Roadbed. The roadbed, including shoulders, shall be constructed, prepared, and finished as provided under Section 208 before placing aggregate base or subbase course material. 304.06 Mixing. Unless otherwise specified, the Contractor may mix the material by any one of the three following methods and shall incorporate additives when required. (a) Stationary plant method.—The materials shall be mixed in an approved mixer. Water shall be added during the mixing operation in the amount necessary to provide the moisture content for compacting to the specified density. After mixing, the material shall be transported to the job site while it contains the proper moisture content and shall be placed on the roadbed by means of an approved appregate spreader. |