C hydrated lime additive system an approved hydrated

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c. Hydrated Lime Additive System - An approved hydrated lime additive system shall be provided. This system shall uniformly feed the -required quantities of hydrated lime and water to the total aggregate and thoroughly mix these materials prior to their entering the asphalt plant drier. The hydrated lime additive system shall be Interlocked with the aggregate cold feed system in order to provide continual treatment of the aggregate. Adequate precautions shall be taken to protect the hydrated lime from loss or damage due to the weather, ie. enclosed storage sheds with concrete flooring, storage silos, etc. The capacity of a11 components of the hydrated lime additive system shall be such as to ensure the continuous application of hydrated lime as specified. Hydrated lime may be added dry or in slurry form. When added dry. the hydrated lime storage si1o and the feeder shall have satisfactory means of preventing arching or intermittent flow. A sufficient number of vibrators, augers and the like may be required to ensure the uniform and continuous flow of lime. Sufficient water spray bars shall be provided to supply 0.5% to 4.0% water by weight of aggregate. Both the lime and water additive devices shall have well defined controls to enable easy checking, setting and calibration. When hydrated lime is added as a slurry, a minimum of two slurry chambers will be provided. One chamber will be used for proportioning the hydrated lime and water into slurry consistency as directed by the Engineer. The second slurry chamber shall contain the mixed slurry and shall be provided with an accurate metering device with well defined settings to enable easy checking, setting and calibration. Both chambers shall be equipped with continuous mixing paddles or recirculating pumps in order to prevent the slurry mixture from separating.
IV-9
ASPHALT WORKS The hydrated lime system shall also include a mixing device of the drum, pugmill or other acceptable type. This device shall thoroughly mix the hydrated lime, water and total aggregate so that the • resultant mixture is uniform in appearance and moisture content. The mixture may then be transferred directly to the asphalt plant drier or stockpiled for later use. Mixed material remaining in stockpile for more than 30 days may require additional treatment. d. Drier - A drier of satisfactory design shall be provided. The drier shall be capable of uniformly drying and heating the aggregate to the moisture and temperature required without leaving any visible unburned oil or carbon residue on the aggregate when discharged from the drier. e. Dust Collector - The plant shall be provided with a dust collector designed to waste, or to return in a constant and uniform flow to the hot elevator, all or part of the material collected. Prior to permitting the return of such collected dust, the Engineer will examine its characteristics in relation to the mix requirements and will designate the quantity to be returned.

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