Aniruddha Baral, Vikram Kumar, Jeffery R. Roesler, Nishant Garg
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引用次数: 0
Abstract
Waste-to-energy (WTE) plants generate fly ashes that are often destined for the landfill. These ashes are rich in chlorine, zinc, and various heavy metals. Here, we investigate the feasibility of their incorporation within cementitious systems in the context of a novel treatment process that chemically binds chlorines into chlorellestadite. Untreated ashes enhance the hydration kinetics and strength, likely due to excess Cl. However, the treated ashes retard the hydration because of the presence of ZnO (2–6 wt%). This retardation was successfully mitigated with up to 2 % calcium nitrate additive, resulting in cement-ash pastes that had mechanical strength comparable to 100% cement pastes. The untreated ashes leached excess Cl and led to the precipitation of hydrocalumite, whereas the treated ash–cement pastes were free from this phase. Finally, for ashes incorporated in hardened cement pastes, the leaching of heavy metals such as Pb and Cr was well under the toxicity limit, for both treated and untreated ashes. In summary, untreated ashes may find end use in unreinforced concrete applications, and treated ashes may be used within reinforced concrete, at least up to 10% cement replacement level.
期刊介绍:
The Chemical Engineering Journal is an international research journal that invites contributions of original and novel fundamental research. It aims to provide an international platform for presenting original fundamental research, interpretative reviews, and discussions on new developments in chemical engineering. The journal welcomes papers that describe novel theory and its practical application, as well as those that demonstrate the transfer of techniques from other disciplines. It also welcomes reports on carefully conducted experimental work that is soundly interpreted. The main focus of the journal is on original and rigorous research results that have broad significance. The Catalysis section within the Chemical Engineering Journal focuses specifically on Experimental and Theoretical studies in the fields of heterogeneous catalysis, molecular catalysis, and biocatalysis. These studies have industrial impact on various sectors such as chemicals, energy, materials, foods, healthcare, and environmental protection.