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Optimization effects and mechanisms of multi-admixture solid wastes such as fly ash and granulated blast furnace slag on the properties of cement mortar

Year: 2026

Type: article

Abstract: To promote the synergistic utilization of mountain sand resources with solid wastes such as fly ash (FA), ground granulated blast-furnace slag (GGBFS), and silica fume (SF) in cement-based materials, this study incorporates mountain sand (including stone powder) into an integrated composite binder system of “cement + FA + GGBFS + SF + mountain sand.” The effects of single-, binary-, and ternary-admixture scenarios on the workability, compressive strength, and chloride-ion penetrability of cement mortars were systematically investigated. In addition, a synergy index for multi-admixture systems (SCI) and an equivalent activity coefficient (k) were proposed to quantitatively identify synergistic and inhibiting regimes. The results indicate that the mountain sand replacement ratio exhibits a distinct “optimum range”: at 20%–40% replacement, the compressive strength is essentially maintained or slightly improved, while the charge passed decreases from 2800 to ∼2500 C; excessive replacement leads to deterioration in both fluidity and durability. In the single-admixture systems, FA markedly increases workability but reduces early-age strength; GGBFS at 5%–15% simultaneously improves strength at all curing ages and lowers the charge passed; SF at 3%–5% enhances both strength and durability at the expense of some fluidity. In the multi-admixture systems, the ternary blend of FA + GGBFS + SF at a total replacement level of 30% delivers the best overall performance in terms of workability, strength development over the full age range, and resistance to chloride-ion penetration, demonstrating a pronounced nonlinear synergistic effect. The SCI–k relationship further shows that k = 0.235–0.240 corresponds to the optimal synergy-enhancement interval for comprehensive performance, whereas higher k values induce inhibitory effects on later-age strength and workability.

Source: AIP Advances

DOI: 10.1063/5.0316780

Authors: Song Xu, Jianeng Zhu, Yunyu Bai, Bo Li, Jiangang Wang

Institutions: China Geological Survey, Yunnan Environmental Protection Bureau, Kunming University of Science and Technology

Language: English

Topic: Concrete and Cement Materials Research

Subfield: Civil and Structural Engineering

Field: Engineering

Domain: Physical Sciences

SDGs: Responsible consumption and production, Industry, innovation and infrastructure

Open Access status: gold

Estimated APC paid: $1,350