Evolution of thermal and mechanical properties of mine tailings and fly ash mixtures during curing period

Abstract

Fly ash is often used as a binder for modifying the properties of geomaterials, such as organic and expansive soils, sludge from water treatment, dredged sediments, mine tailings, etc. Changes in thermal and mechanical properties of compacted mixtures of mine tailings and fly ash are studied over a curing period of 120 h. The study includes the measurement of thermal conductivity, temperature, unconfined compressive strength, and elastic modulus. Effects of the amount of fly ash added to mine tailings, molding water content, and compaction energy on these properties are investigated. Pore-size distribution and surface texture are analyzed to characterize the microstructures of fly ash treated–mine tailings. Relationships between the thermal conductivity and properties that capture packing and mechanical characteristics of mine tailings and fly ash mixtures are established. These observations provide enhanced understanding of thermal, mechanical, and structural properties of fly ash–treated mine tailings, which is associated with the hydration process at the early stage of the mixtures.