Analysis of process energy use of asphalt-mixing plants

Abstract

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 are widely used as a road-paving material. A large part of the process energy use is for drying and heating the aggregates. Statistical analyses using historical energy-consumption data show a high correlation between specific energy requirements and rainfall level. Field sampling and laboratory investigations indicate that aggregate moisture content and rainfall level are closely related and that aggregate moisture content is a critical determinant of process-energy requirements. Measures for maintaining a low aggregate moisture level, such as isolating aggregate stockpiles from rain, offer great potential for energy savings. We present estimates of these savings, establish process-energy flows, and compare the performances of the two plants.