The Safe Disposal of Fly Ash in Pavement or Earth Structures Not Requiring High Strength Materials

Highway agencies throughout the country face the challenge of safe disposal of various waste products in pavements and earth structures. Some of these waste products can be hazardous to the environment as suggested by the EPA. One such product is fly ash, which is produced during coal combustion in combination with bottom ash. More than 70 million tons of fly ash are produced in the USA each year. Safe disposal of such an enormous quantity of material is critical. One possible destination is the 2.3 million miles of highways Various researchers and highway agencies have used fly ash but in small quantities. More uses are needed. The present study was undertaken to evaluate the use of fly ash in earth structures not requiring high strength such as vertical moisture barriers, shoulders, or as a backfill material. Fly ash was used in combination with cement and sand to form a fly ash-cement-sand mortar. The results of the study are reported in this paper.