ANALYSIS OF PROCESS ENERGY USE OF ASPHALT-MIXING PLANTS

We present the results of a study on process energy use of two asphalt -mixing plants. The production process involves the mixing of granite aggregates and bitumen to give asphalt mixtures. The mixtures arc wide ly used as a road-paving material. A large pan of the process energy u se is for drying and heating the aggregates. Statistical analyses usin g historical energy-consumption data show a high correlation between s pecific energy requirements and rainfall level. Field sampling and lab oratory investigations indicate that aggregate moisture content and ra infall level are closely related and that aggregate moisture content i s a critical determinant of process-energy requirements. Measures for maintaining a low aggregate moisture level, such as isolating aggregat e stockpiles from rain, offer great potential for energy savings. We p resent estimates of these savings, establish process-energy flows, and compare the performances of the two plants.