TY - JOUR

T1 - Effect of clay mineralogy and organic matter on strength development of geopolymer-stabilized soils

AU - Lazorenko, Georgy

AU - Kasprzhitskii, Anton

N1 - The synthesis of materials and preliminary characterization were carried out with the support of the Russian Science Foundation (No. 19-79-10266, https://rscf.ru/project/19-79-10266/). The detailed structural analysis and performance testing were supported by the Ministry of Science and Higher Education of the Russian Federation (Grant No. FSUS-2024-0027).

PY - 2026/11

Y1 - 2026/11

N2 - This study investigates the coupled influence of soil mineralogical composition and organic matter content on the strength development of geopolymer (GP)-stabilized soils. Six artificial soils with systematically varied proportions of sand, clay minerals, and organic matter were stabilized using a metakaolin-based geopolymer binder. Unconfined compressive strength (UCS) was evaluated at curing ages of 1, 3, 7, 14, and 28 days, complemented by scanning electron microscopy (SEM), SEM with energy-dispersive X-ray spectroscopy (SEM-EDS), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) analyses to elucidate microstructural and phase evolution mechanisms. Mixed-mineral soils achieved high 28-day UCS values of 26–31 MPa, with strength governed by the continuity of the geopolymer binder and the integrity of the mineral skeleton. Smectite-rich clay soil exhibited delayed but substantial strength development, reaching UCS comparable to mixed-mineral systems. In contrast, increasing organic matter content resulted in a pronounced reduction in UCS, decreasing to 2 MPa in peat-dominated soil, due to disruption of binder continuity and dilution of reactive mineral phases, as well as interactions with the alkaline pore solution that can limit aluminosilicate dissolution and gel formation. The results highlight the critical role of mineral framework continuity and identify intrinsic limitations for GP stabilization of organic-rich soils.

AB - This study investigates the coupled influence of soil mineralogical composition and organic matter content on the strength development of geopolymer (GP)-stabilized soils. Six artificial soils with systematically varied proportions of sand, clay minerals, and organic matter were stabilized using a metakaolin-based geopolymer binder. Unconfined compressive strength (UCS) was evaluated at curing ages of 1, 3, 7, 14, and 28 days, complemented by scanning electron microscopy (SEM), SEM with energy-dispersive X-ray spectroscopy (SEM-EDS), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) analyses to elucidate microstructural and phase evolution mechanisms. Mixed-mineral soils achieved high 28-day UCS values of 26–31 MPa, with strength governed by the continuity of the geopolymer binder and the integrity of the mineral skeleton. Smectite-rich clay soil exhibited delayed but substantial strength development, reaching UCS comparable to mixed-mineral systems. In contrast, increasing organic matter content resulted in a pronounced reduction in UCS, decreasing to 2 MPa in peat-dominated soil, due to disruption of binder continuity and dilution of reactive mineral phases, as well as interactions with the alkaline pore solution that can limit aluminosilicate dissolution and gel formation. The results highlight the critical role of mineral framework continuity and identify intrinsic limitations for GP stabilization of organic-rich soils.

KW - Alkali-activated materials

KW - Geopolymer

KW - Metakaolin

KW - Organic matter

KW - Soil stabilization

UR - https://www.scopus.com/pages/publications/105042550634

UR - https://www.mendeley.com/catalogue/aecbdbcc-c3d2-31f5-9de9-a59d59e236f3/

U2 - 10.1016/j.clay.2026.108321

DO - 10.1016/j.clay.2026.108321

M3 - Article

VL - 292

JO - Applied Clay Science

JF - Applied Clay Science

SN - 0169-1317

M1 - 108321

ER -