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One-part alkali-activated slag binder for cemented fine tailings backfill: proportion optimization and properties
Gengjie Zhu1,2, Wancheng Zhu1, Zhaojun Qi2
1Center for Rock Instability and Seismicity Research, School of Resource and Civil Engineering, Northeastern University, Shenyang, 110819, China.
Summary
Alkali-activated slag (AAS) offers a sustainable alternative binder for cemented fine tailings backfill (CFTB). This industrial waste-based material demonstrates superior strength and workability compared to ordinary Portland cement (OPC).
Area of Science:
- Materials Science
- Civil Engineering
- Environmental Science
Background:
- Cemented fine tailings backfill (CFTB) traditionally uses ordinary Portland cement (OPC).
- There is a growing need for sustainable and environmentally friendly binders in mining and construction.
- Industrial solid wastes present an opportunity for developing alternative binders.
Purpose of the Study:
- To investigate a one-part alkali-activated slag (AAS) binder as a sustainable alternative to OPC for CFTB.
- To evaluate the performance of AAS-based CFTB in terms of mechanical strength, hydration products, and workability.
- To promote the utilization of industrial solid waste in backfill applications.
Main Methods:
- Formulation of a one-part alkali-activated slag (AAS) binder using ground-granulated blast furnace slag, desulfurized gypsum, and hydrated lime.
- Preparation and testing of cemented fine tailings backfill (CFTB) using the developed AAS binder.
- Comparative analysis of AAS-based CFTB with ordinary Portland cement (OPC) based CFTB regarding mechanical strength, hydration products, and workability.
Main Results:
- The optimal AAS binder composition (67.83 wt.% slag, 25.92 wt.% desulfurized gypsum, 6.25 wt.% hydrated lime) achieved 1.7-3.2 times higher strength than OPC.
- AAS hydration produced calcium silicate hydrate gel and ettringite with an interlocking needles structure and high bound water.
- AAS binder exhibited 48% less hydration heat than OPC and improved CFTB workability for up to 20 hours.
Conclusions:
- A one-part alkali-activated slag (AAS) binder is a viable and high-performance alternative to OPC for CFTB.
- AAS-based CFTB offers enhanced mechanical properties, improved workability, and reduced environmental impact.
- This study supports the cost-effective and durable production of environmentally friendly cemented fine tailings backfill using industrial solid waste.
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