403ASPHALTIC CONCRETE HOT PLANT REQUIREMENTS

295 Immediately prior to placement of the sealant, the joints shall be cleaned as approved by the Engineer. 402- 7.04 Method of Measurement: Edge sealing will be measured by the linear foot of longitudinal edge joint sealed. 402- 7.05 Basis of Payment: The accepted quantities of edge sealing, measured as provided above, will be paid for at the contract unit price per linear foot of edge seal, complete i n place. 403- 1 Description: When referenced in individual specifications, the asphaltic concrete hot plant shall meet the requirements specified herein. 403- 2 Requirements: Mixing plants shall conform to the requirements of AASHTO M 156 except as modified herein. Mineral admixture shall be proportioned by weight. The mineral admixture shall be added and thoroughly mixed with the mineral aggregate by means of a mechanical mixing device prior to the mineral aggregate and mineral admixture entering the dryer. For all asphaltic concrete mixes except ACFC ( specified in Sections 407 and 411 of the specifications) and AR -ACFC ( specified in Section 414 of the specifications), the moisture content of the combined mineral aggregate shall be a minimum of 3 percent by weight of the aggregate during the mixing process. For ACFC and AR -ACFC mixes, the mineral aggregate shall be wet with free moisture on the surface of the aggregate just prior to the mixing process. To ensure that adequate mixing water is available on the surface of the aggregate, the Engineer may require that the mineral aggregate for ACFC and AR -ACFC mixes have a moisture content of up to 1- 1/2 per cent above the combined water absorption. The mineral admixture shall be weighed utilizing an approved weigh system, with a weight totalizer prior to entry into the mecha nical mixing device. The mechanical mixing device shall be a pugmill type mixer which is in good working condition and which consists of at least two motorized shafts with mixing paddles. The mixing device shall be designed such that the mixture of aggregate and admixture is moved in a near horizontal direction by the mixing paddles, without the aid of TABLE OF CONTENTS INDEX 296 conveyor belts, for a distance of at least 3 feet. The rate of aggregate feed shall not exceed the mixing device’s rated capacity in tons per hour. The m ixer shall be constructed to minimize the loss of mineral admixture. The mixer shall be located in the aggregate delivery system at a location where the mixed material can be readily inspected on a belt prior to entry into the dryer. The mixing device shall be capable of effective mixing in the full range of asphaltic concrete production rates. A positive signal system shall be provided and utilized during production whereby the mixing shall automatically be stopped if the mineral admixture is not being i ntroduced into the mineral aggregate. The plant will not be permitted to operate unless the signal system is in good working condition. The contractor's plant and equipment shall be constructed and operated so that there is not a significant loss of mineral admixture through the dust collection system of the plant. For mixing plants other than batch plants, bituminous material and mineral aggregate shall be proportioned by either volume or weight. When a batch plant is used, bituminous material and mineral aggregate shall be proportioned by weight. Weighing shall be performed with all receptacles and scales insulated against the vibration or movement of the rest of the plant. The insulated receptacles and scales shall be such that the error in weighing, w hile the entire plant or any part of the plant is operating, shall not exceed 2 percent for the bituminous material and the individual mineral aggregate components, or 1- 1/2 percent for any batch. Weighing of bituminous material shall be done in a heated, insulated bucket suspended from a springless dial scale system. Mineral aggregate from each individual stockpile/hot bin shall be properly proportioned and introduced into the asphaltic concrete. A positive signal system shall be provided and utilized during production to indicate the low level of mineral aggregate in the bins. The plant will not be permitted to operate unless the signal system is in good working condition. Each bin shall have an overflow chute or a divider to prevent material from spilling into adjacent bins. The introduction of bituminous material shall be controlled by an automated system fully integrated with the controls for mineral aggregate and mineral admixture. The contractor shall provide daily documentation of the weight and proportion of each individual component (mineral aggregate, mineral admixture, and bituminous material) incorporated into the mix, within three days of the production, excluding weekends and holidays. When a dedicated plant is being used, plant startup waste shall be shown in the hot plant documentation. In addition, when reclaimed asphaltic pavement (RAP) is used, the contractor shall provide daily TABLE OF CONTENTS INDEX