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Hot Mix Asphalt <br /> Facilities 300 PROCESS AND CONTROL <br /> A normal batch cycle time is 45 to 60 seconds. This means that a batch mix <br /> facility can produce 60 to 80 batches per hour. Therefore, a facility with a 5 ton <br /> (10,000 lbs) pugmill can produce 300 to 400 tons per hour of hot mix asphalt. <br /> Pugmill The chamber in which the asphalt and aggregate are mixed is called a <br /> pugmill or mixer. A twin-shaft mixer is commonly used in modem HMA <br /> facilities. In a batch mix facility, this unit is mounted directly beneath the <br /> weigh hopper and asphalt distributor, see figure 301.4. These twin-shaft <br /> mixers consist of a lined mixing chamber with two horizontal shafts on which <br /> several paddle shanks, each with two paddle tips, are mounted' <br /> Figure 301.4 Asphalt Concrete Pugmill Mixer [3] <br /> Asphalt cement is introduced into the pugmill after the aggregate has been de- <br /> posited from the weigh hopper and dry-mixing is completed. Wet-mixing time <br /> begins when the asphalt cement is added.' <br /> The batch mixing time is the time period between the start of the opening of <br /> the weigh hopper dumping mechanism and the start of the opening of the <br /> discharge gate. The mixing time is the time necessary to obtain a homogene- <br /> A„nnc4 loon <br />