COAL REFUSE AND FLY ASH COMPOSITIONS: POTENTIAL HIGHWAY BASE-COURSE MATERIALS

The necessity of using waste products in construction is becoming both evident and crucial as waste disposal continues to have a negative impact on the environment, disposal costs escalate, and traditional materials become scarce and expensive. Two by-products of the coal industry--coal refuse and fly ash--show promise for use in highway base-course applications. The already abundant supplies of these materials are expected to increase. Summarized in this paper are results of studies of the physical and engineering properties of both unstabilized and stabilized mixtures of coal refuse and fly ash. In addition, comparisons of performances of several hypothetical pavement systems are presented. The base courses of the pavements were either a crushed stone or coal refuse and fly ash mixtures. Findings indicate that stabilzed coal refuse and fly ash mixtures are technically feasible base-course materials. In-service feasibility of the mixtures should be established by appropriate field testing. Unstabilized mixtures appear unsuitable for base-course applications because of questionable wet-dry and freeze-thaw durability. Both traditional substances and waste products should be considered as candidate construction materials. Technology for assessing competitive materials is available for many applications. (Authors)