Reactive MgO-modified slag-based binders for cemented paste backfill and potential heavy-metal leaching behavior. (6th September 2021)

• Record Type: Journal Article
• Authors: Zhao, Dengfeng
• Is Part Of: Construction & building materials. Volume 298(2021)
• Publication Date: 2021-09-06
• Subjects: Reactive MgO -- Heavy metal -- Mine backfill -- Mechanical strength -- Copper slag; Building materials -- Periodicals; 624.18
• DOI: 10.1016/j.conbuildmat.2021.123894
• Languages: English
• ISSNs: 0950-0618

Abstract

Highlights: The addition of reactive MgO decreased flowability of the CPB slurry. Adding reactive MgO increased the compressive strength of the CPB samples. The presence of reactive MgO showed better immobilization effect on heavy metals. Abstract: As a binder to replace Portland cement completely for cemented paste backfill, the use of clinker-free binders combined with copper slag is proposed to achieve the purpose of low-cost mine backfilling and safe disposal of copper slag. We studied the influence of reactive MgO on the properties of cemented paste backfill (CPB) samples, including rheological characteristics, setting time, and compressive strength as well as the heavy-metal leaching behavior. The results indicated that the addition of reactive MgO increased the yield stress of the fresh CPB samples, leading to decreased flowability, whereas the compressive strength of the CPB samples was increased. Besides, the release amount of all the investigated heavy metals was decreased in the presence of reactive MgO due to the formation of additional hydrotalcite-like phases with the formation of a more compact structure. These results provide a strategy for the safe large-scale utilization of copper slag.