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Mix <br /> 300 PROCESS AND CONTROL Hot acilAsshalt <br /> This section describes the hot mix asphalt process, the types of facilities, the <br /> emissions from the process, and the process components and maintenance. <br /> The information in this section comes largely from resources of the following References <br /> organizations, Asphalt Institute, California Department of Transportation, <br /> Asphalt Recycling & Reclaiming Association, U. S. Environmental Protec- <br /> tion Agency (EPA),and the National Asphalt Pavement Association. <br /> Specific references are denoted by a number at the end of a paragraph or <br /> Section title and figure credits by a number in brackets after the figure title, <br /> indicating the numerical order of the source at the end of this section. <br /> 301 DESCRIPTION OF THE HOT MIX ASPHALT PROCESS <br /> Hot mix asphalt (HMA) facilities produce asphaltic concrete. Asphaltic Asphaltic <br /> concrete is a mixture of well graded, high quality aggregate and asphalt Concrete <br /> cement heated and mixed in measured quantities. <br /> Aggregate is any hard, inert mineral material used for mixing in graduated Aggregate <br /> particles or fragments. It includes sand, gravel, crushed stone, slag, rock dust <br /> or powder. Aggregate for asphalt paving are classified generally according to <br /> their source or means of preparation. They include processed aggregate and <br /> synthetic or artificial aggregate. The amount of mineral aggregate in asphalt <br /> paving mixtures is generally 92 to 96 percent by weight and 75 to 85 percent <br /> by volume. <br /> Asphalt is a dark brown to black cementitious material in which the predomi- Asphalt <br /> nating constitutents are bitumens which occur in nature or are obtained in Cement <br /> petroleum processing. Asphalt cement is asphalt specially prepared as to <br /> quality and consistency for direct use in the manufacture of asphalt pave- <br /> ments. See appendix A for typical temperatures for uses of asphalt <br /> The basic HMA facility process involves removing moisture from the Basic <br /> aggregate, heating the aggregate, grading the aggregate, heating the asphalt, Operation <br /> proportioning the asphalt and aggregate, and mixing the asphalt and aggregate <br /> until the aggregate particles are coated uniformly with asphalt See appendix <br /> B for ASTM Standard Specifications for Mix Plants for Hot Mixed,Hot Laid <br /> Bituminous Paving Mixture. <br /> August 1990 Page 300 - 1 <br />