Damage constitutive model of fly ash–cementitious iron tailings powder under small strain

With the vigorous development of industrial economy, the production capacity and level have been significantly improved, but at the same time, a large amount of iron tailings, fly ash and a series of bulk solid waste materials have been accumulated. These industrial wastes have caused serious impact on the ecological environment. How to deal with them effectively is an urgent problem that needs to be solved. The aim of this study was to investigate the effect of cement and fly ash compound admixtures on the mechanical properties of iron tailings powder (ITP). Hence, different mixing ratios of cement and fly ash were used to prepare two kinds of ITP-based materials. A range of uniaxial compressive strength (UCS), resonance column (RC), scanning electron microscopy and X-ray diffraction tests were conducted to investigate the roles of cement, fly ash and curing age in ITP solidification. A random one-dimensional damage model was imported to study the damage evolution of ITP materials using the UCS and RC test results, which showed that cement and fly ash enhanced the unconfined compression strength and small-strain stiffness of ITP. When 5–10% fly ash content was used as a substitute for 10% cement, the unconfined compressive strength and small-strain modulus of cement–fly ash–ITP increased with curing age. The microstructure and mineralogy analysis confirmed that fly ash enhanced the strength of the material. Overall, the damage constitutive model effectively represented the randomness of the compressive strength and stress–strain relationship of ITP materials under unconfined conditions.