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<p>This study investigates the geotechnical, microstructural and environmental performance of alkali-activated clayey soils stabilised using a novel blend of marble dust (MD) and nano silica (NS) with sodium hydroxide (NaOH) as the chemical activator. A series of mixes were formulated with varying binder contents (10–20%), NaOH molarities (4–12&#xa0;M), and activator-to-binder (A/B) ratios (0.6–0.8). The treated soils exhibited substantial strength enhancement, achieving a maximum unconfined compressive strength of 8.93&#xa0;MPa after 28 days of curing at 75&#xa0;°C, compared to 1.85&#xa0;MPa obtained at 7 days under ambient conditions. Swell pressure decreased from 357&#xa0;kPa in untreated soil to as low as 64&#xa0;kPa in stabilised samples. Durability assessments showed strong resistance to wet–dry cycling, with minimal mass loss (5.8%) and 69.4% residual strength retention. Thermogravimetric analysis confirmed the formation of stable reaction products such as C(Na)-A-S-H and CaCO₃. FESEM imaging revealed a transition from a porous, flaky raw soil structure to a dense, gel-rich matrix in treated samples. Furthermore, leaching studies showed the heavy metal concentrations were within permissible drinking water limits. The results validate the potential of MD and NS as sustainable, high-performance alternatives for soil stabilisation.</p>

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Geotechnical, environmental and microstructural behaviour of alkali-activated clay soil with marble dust and nano silica

  • 期刊论文

  • 发表日期：

    2026年3月26日

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  • Vinodhkumar Shanmugasundaram,
  • Raja Kanagaraju,
  • Karthikeyan Selvarajan,
  • Rampradheep Gobi Subburaj

摘要

This study investigates the geotechnical, microstructural and environmental performance of alkali-activated clayey soils stabilised using a novel blend of marble dust (MD) and nano silica (NS) with sodium hydroxide (NaOH) as the chemical activator. A series of mixes were formulated with varying binder contents (10–20%), NaOH molarities (4–12 M), and activator-to-binder (A/B) ratios (0.6–0.8). The treated soils exhibited substantial strength enhancement, achieving a maximum unconfined compressive strength of 8.93 MPa after 28 days of curing at 75 °C, compared to 1.85 MPa obtained at 7 days under ambient conditions. Swell pressure decreased from 357 kPa in untreated soil to as low as 64 kPa in stabilised samples. Durability assessments showed strong resistance to wet–dry cycling, with minimal mass loss (5.8%) and 69.4% residual strength retention. Thermogravimetric analysis confirmed the formation of stable reaction products such as C(Na)-A-S-H and CaCO₃. FESEM imaging revealed a transition from a porous, flaky raw soil structure to a dense, gel-rich matrix in treated samples. Furthermore, leaching studies showed the heavy metal concentrations were within permissible drinking water limits. The results validate the potential of MD and NS as sustainable, high-performance alternatives for soil stabilisation.