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BULLETIN OF THE CHINESE CERAMIC SOCIETY ›› 2026, Vol. 45 ›› Issue (7): 2448-2465.DOI: 10.16552/j.cnki.issn1001-1625.2026.0067

• Solid Waste and Eco-Materials • Previous Articles     Next Articles

Optimization of Mix Proportion and Micro-Mechanism Study of Multi-Source Solid Waste-Based Cementitious Backfill

WANG Yanheng(), ZHANG Jiawei, REN Kai, YAN Guochao(), KONG Shaoqi, LI Gang, LI Boyu, WU Kuangkuang   

  1. College of Mining Engineering,Taiyuan University of Technology,Taiyuan 030024,China
  • Received:2026-01-19 Revised:2026-02-28 Online:2026-07-15 Published:2026-08-13
  • Contact: YAN Guochao

Abstract:

Addressing the existing research gap in understanding the synergistic effects and optimal mix design of multi-source solid waste-based cementitious backfill(MSSWCB), as well as the unclear hydration mechanisms, strength development, and microstructural evolution of individual components within complex systems, this study utilized coal gangue as aggregate, fly ash and steel slag as primary cementitious components, carbide residue and desulfurization gypsum as composite activators, supplemented with a small amount of cement (adding an amount equal to the mass of coal gangue), to prepare a MSSWCB for mine backfilling. Through orthogonal experiments and microscopic testing methods, the mechanical properties and bonding mechanism of this material were investigated. Results indicate that the compressive strength of MSSWCB increases significantly with curing age, with average compressive strength at 3, 7, and 28 d being 2.058, 3.604, and 7.211 MPa, respectively. The optimal mix ratio (the mass ratio of coal gangue aggregate, cement, fly ash, steel slag, calcium carbide slag, desulfurization gypsum, water is 1∶1∶1.9∶0.9∶0.3∶0.15∶1.615) achieves a 28 d compressive strength of 12.96 MPa. Analysis of influencing factors indicates that early strength is primarily controlled by the water-binder ratio, while mid-term strength is jointly affected by both the water-binder ratio and the amount of calcium carbide slag added. The key factor affecting later-stage strength is the fly ash content. Through microscopic analysis, the hydration products of MSSWCB at different curing stages are revealed: early-stage products are dominated by ettringite (AFt), mid-stage saw significant generates calcium silicate hydrate (C-S-H) and calcium aluminum silicate hydrate (C-A-S-H) gels, and late-stage C-(A)-S-H gel becomes the primary cementing phase. Structural densification forms the microscopic basis for strength development. This study provides experiment support and technical guidance for the resource utilization of multi-source solid waste and the development of green mine backfill cementitious materials.

Key words: multi-source solid waste, cementitious backfill material, compressive strength, orthogonal test, microstructure, hydration mechanism

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