Key Takeaways & Executive Findings
- •• PVA fibers act as a 'skeleton bridge' to significantly improve concrete toughness, while lithium slag (LS) promotes hydration and synergizes with fibers to enhance mechanical properties. • EVA copolymer inhibits hydration via an 'organic isolation' effect, degrading concrete mechanical performance, highlighting the need for careful admixture selection. • The optimal R3-group material demonstrated effective inhibition of roadway deformation in on-site applications, confirming its reliability for coal-rock dynamic disaster prevention. • LS-and-fiber-reinforced concrete offers environmental, economic, and disaster-prevention benefits, supporting large-scale solid waste disposal and sustainable mining practices.
Abstract
Coal and rock dynamic disasters are always major hidden dangers threatening mine safety production. Many researchers use cement concrete material as filling and energy-absorption materials. However, the current material toughness is not sufficient to meet the requirements of mine disaster prevention. Based on this, in order to find the optimal-ratio material that combines strength and toughness, the synergistic mechanism of lithium slag (LS), ethylene–vinyl acetate (EVA) copolymer, and polyvinyl alcohol (PVA) fiber mixtures in improving the mechanical properties of cement concrete, as well as the mechanism of microscopic phase evolution, was analyzed through macroscopic experiments, mesoscopic characterization, microscopic analysis, theoretical calculations, and comprehensive evaluation. The stress-strain curves obtained from the uniaxial compressive strength tests of specimens with different admixtures and fibers were investigated, and the characteristics of different stages were analyzed. The mechanical properties of different admixtures and fiber-reinforced materials, including their advantages and disadvantages, were compared through weighted comprehensive evaluation. The entire process of material failure, ranging from pore compaction, crack initiation, crack propagation, specimen instability to crack penetration, was explained via macroscopic fracture morphology, and the mechanical mechanism of how different admixtures affect the mechanical properties of concrete materials was revealed. The microscopic mechanism and the phase-evolution process of how the admixture affects concrete properties were elucidated using X-ray diffraction (XRD), hydration reaction theory, and Fourier transform infrared spectroscopy (FTIR). Furthermore, scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) was used to reveal the interfacial pore state and element distribution of the internal microstructure of concrete. The results show that PVA fiber bars can play the role of a ''skeleton bridge'' to improve the toughness of materials. LS can effectively promote the hydration process and cooperate with PVA fiber bars to enhance the mechanical properties of the material. EVA will inhibit the hydration reaction and degrade the material's mechanical properties through the ''organic isolation'' effect. In addition, the on-site application has proven that the R3-group materials in this study can effectively inhibit the deformation of the roadway and possess strong reliability. Finally, the advantages and feasibility of LS-and-fiber-reinforced concrete were discussed from four perspectives: environmental protection, economy, disaster prevention, and development. This paper is expected to provide technical reference for the large-scale disposal of solid waste LS, the performance-optimization direction of concrete materials, and the prevention and control of coal and rock dynamic disasters.
1. Introduction
In the process of coal mining, dynamic disasters such as rock burst and coal and gas outburst are always major hidden dangers threatening mine safety production [1–3]. Once these disasters break out, they will not only cause serious damage to mine roadways and production equipment, but also result in huge economic losses and significant casualties. Therefore, effective prevention and control measures are crucial for ensuring mine safety.
Currently, cement concrete is widely used as a filling and energy-absorption material in mines due to its high strength and low cost. However, its inherent brittleness and insufficient toughness limit its ability to absorb dynamic impact energy, making it inadequate for disaster prevention. To address this, researchers have explored various additives, such as fibers and mineral admixtures, to improve the toughness and energy absorption capacity of concrete. Among these, lithium slag (LS), a solid waste from lithium extraction, has shown potential as a supplementary cementitious material, while polyvinyl alcohol (PVA) fibers are known for their crack-bridging ability. This study investigates the synergistic effects of LS, EVA copolymer, and PVA fibers on the mechanical properties and microscopic phase evolution of concrete, aiming to develop an optimal material for preventing coal-rock dynamic disasters.
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Xuyang Bai, Junwen Zhang, Yulin Li, Zeyu Liu, Zhixiang Song, Yang Zhang, Xukai Dong, Weizheng Xu, Xian Li, Shaokang Wu (2025). Microscopic phase evolution mechanism of lithium slag and fiber synergistically enhancing concrete toughness: Perspective of preventing coal-rock dynamic disasters through energy absorption. SinoTechIntel Verified Research. https://doi.org/10.1016/j.ijmst.2025.06.007
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Frequently Asked Questions
What is the role of PVA fibers in enhancing concrete toughness?
PVA fibers act as a 'skeleton bridge' within the concrete matrix, effectively bridging cracks and preventing their propagation, thereby significantly improving the material's toughness and energy absorption capacity.
How does lithium slag (LS) affect the mechanical properties of concrete?
Lithium slag promotes the hydration process of cement, leading to a denser microstructure and enhanced mechanical properties. When combined with PVA fibers, LS synergistically improves both strength and toughness, making the concrete more suitable for mine disaster prevention.
What is the effect of EVA copolymer on concrete performance?
EVA copolymer inhibits the hydration reaction through an 'organic isolation' effect, which degrades the mechanical properties of concrete. Therefore, its use should be carefully controlled to avoid compromising material performance.
How does the R3-group material perform in on-site applications?
The R3-group material, which contains the optimal combination of LS and PVA fibers, effectively inhibited roadway deformation in on-site tests, demonstrating strong reliability and practical applicability for preventing coal-rock dynamic disasters.
What are the environmental and economic benefits of using lithium slag in concrete?
Utilizing lithium slag in concrete provides a sustainable solution for large-scale disposal of this solid waste, reducing environmental pollution. Economically, it lowers material costs and enhances concrete performance, offering dual benefits for the mining industry.
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