Abstract The development of functional and cost-effective landfill liners is crucial for reducing groundwater pollution while maintaining soil quality and environmental integrity. Composite liners, including bentonite and other components such as fly ash or marble dust, are a potential solution. This study looks at the effectiveness of Ganga sand (GS), bentonite (B), and marble dust (MD) composite compositions as landfill liners. Several metrics were tested, including consistency limits, compaction, free swell index (FSI), unconfined compressive strength (UCS) at various curing durations (1, 7, 14, and 28 days), hydraulic conductivity (HC), desiccation cracking, and microstructure analysis (XRD, FE-SEM, and EDAX). The findings indicate that a GS–B–MD composite mix in a 60:20:20 ratio corresponds to the most advantageous design characteristics for landfill liners. This composite mix reduces the liquid limit (LL) and plastic limit (PL) by 37.45% and 23.08%, respectively, while also decreasing the optimal moisture content by 23.53%. In contrast, the maximum dry density (MDD) increases by 11.90%, the FSI rises by 367%, and HC falls significantly by 93.39%. Furthermore, after 28 days of curing, the UCS increases dramatically by 540% and desiccation cracking is very low on the optimum composite mixtures. These findings demonstrate that using a suitable quantity of marble dust, along with other binder materials, not only deals with disposal difficulties but also improves the engineering features of the composite material, making it a viable and sustainable option for landfill liners. Research Highlights <UnorderedList Mark="Bullet"> <ItemContent> Novel composite formulation: Developed and optimized Ganga sand–bentonite–marble dust (GS–B–MD) mixtures as sustainable and cost-effective landfill liner materials using locally available resources. </ItemContent> <ItemContent> Performance optimization: The optimum mix (60% GS–20% B–20% MD) achieved the best combination of strength (UCS = 438 kPa after 28 days), lowest hydraulic conductivity (93.39% reduction), and minimal desiccation cracking. </ItemContent> <ItemContent> Enhanced geotechnical behavior: Addition of bentonite increased plasticity and swelling, while marble dust improved compaction, density, and strength through filler and gradation effects. </ItemContent> <ItemContent> Microstructural evidence: SEM, XRD, and EDAX analyses confirmed dense particle packing, formation of hydrated coatings, and active mineral interactions among quartz, montmorillonite, and calcite phases. </ItemContent> <ItemContent> Desiccation resistance: Crack intensity reduced to 1.12% in the optimized mix, demonstrating superior crack control under thermal drying compared to conventional bentonite liners. </ItemContent> <ItemContent> Sustainability impact: Utilization of marble dust, an industrial waste, offers an eco-friendly alternative to natural clay in liner systems, contributing to circular economy and waste valorization. </ItemContent> </UnorderedList>

Geotechnical properties and microstructural analysis with desiccation cracking study of Ganga sand, bentonite and marble dust composites

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发表日期：

2025年11月25日

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Rajiv Kumar,
Sunita Kumari

摘要

Abstract

The development of functional and cost-effective landfill liners is crucial for reducing groundwater pollution while maintaining soil quality and environmental integrity. Composite liners, including bentonite and other components such as fly ash or marble dust, are a potential solution. This study looks at the effectiveness of Ganga sand (GS), bentonite (B), and marble dust (MD) composite compositions as landfill liners. Several metrics were tested, including consistency limits, compaction, free swell index (FSI), unconfined compressive strength (UCS) at various curing durations (1, 7, 14, and 28 days), hydraulic conductivity (HC), desiccation cracking, and microstructure analysis (XRD, FE-SEM, and EDAX). The findings indicate that a GS–B–MD composite mix in a 60:20:20 ratio corresponds to the most advantageous design characteristics for landfill liners. This composite mix reduces the liquid limit (LL) and plastic limit (PL) by 37.45% and 23.08%, respectively, while also decreasing the optimal moisture content by 23.53%. In contrast, the maximum dry density (MDD) increases by 11.90%, the FSI rises by 367%, and HC falls significantly by 93.39%. Furthermore, after 28 days of curing, the UCS increases dramatically by 540% and desiccation cracking is very low on the optimum composite mixtures. These findings demonstrate that using a suitable quantity of marble dust, along with other binder materials, not only deals with disposal difficulties but also improves the engineering features of the composite material, making it a viable and sustainable option for landfill liners.

Research Highlights

Novel composite formulation: Developed and optimized Ganga sand–bentonite–marble dust (GS–B–MD) mixtures as sustainable and cost-effective landfill liner materials using locally available resources.

Performance optimization: The optimum mix (60% GS–20% B–20% MD) achieved the best combination of strength (UCS = 438 kPa after 28 days), lowest hydraulic conductivity (93.39% reduction), and minimal desiccation cracking.

Enhanced geotechnical behavior: Addition of bentonite increased plasticity and swelling, while marble dust improved compaction, density, and strength through filler and gradation effects.

Microstructural evidence: SEM, XRD, and EDAX analyses confirmed dense particle packing, formation of hydrated coatings, and active mineral interactions among quartz, montmorillonite, and calcite phases.

Desiccation resistance: Crack intensity reduced to 1.12% in the optimized mix, demonstrating superior crack control under thermal drying compared to conventional bentonite liners.

Sustainability impact: Utilization of marble dust, an industrial waste, offers an eco-friendly alternative to natural clay in liner systems, contributing to circular economy and waste valorization.