Investigation into hydrophobic and strength characteristics of weathered red-layer mudstone surface modified by octadecylamine

TY - JOUR

T1 - Investigation into hydrophobic and strength characteristics of weathered red-layer mudstone surface modified by octadecylamine

AU - Zhou, Yuqing

AU - Chen, Xiaobin

AU - Yu, Zhaosheng

AU - Zhang, Jiasheng

AU - Brennan, Andrew

N1 - Publisher Copyright: © 2025 Elsevier Ltd

PY - 2025/7

Y1 - 2025/7

N2 - Weathered red-layer mudstone (WRM) is highly susceptible to water-induced softening and disintegration when utilized as subgrade filling material, posing significant challenges to infrastructure stability. To enhance hydrophobicity and reduce degradation, octadecylamine (ODA) treatment was proposed. Hydrophobicity and mechanical strength were evaluated through contact angle, capillary water absorption, and direct shear tests, with microstructural analysis via scanning electron microscopy. Results showed that ODA intercalated between the WRM clay mineral layers, significantly reducing the porosity and forming a needle-like convex structure similar to the surface of a lotus leaf. ODA increased contact angle of WRM surface from 0° to over 90°, reaching up to 143° with higher ODA content, though excessive concentrations caused surface cracking. The rise height of capillary water decreased with the increase of ODA content, and 3 % ODA effectively prevented water ingress. Lower ODA percentages were also effective, especially when a secondary layer or heating method was used. In terms of mechanical strength, the internal friction angle and cohesion increased first and then decreased with the increase of ODA, peaking at 1 %. The research results can provide reference for subgrade construction in WRM area and improve utilization rate of subgrade filling.

AB - Weathered red-layer mudstone (WRM) is highly susceptible to water-induced softening and disintegration when utilized as subgrade filling material, posing significant challenges to infrastructure stability. To enhance hydrophobicity and reduce degradation, octadecylamine (ODA) treatment was proposed. Hydrophobicity and mechanical strength were evaluated through contact angle, capillary water absorption, and direct shear tests, with microstructural analysis via scanning electron microscopy. Results showed that ODA intercalated between the WRM clay mineral layers, significantly reducing the porosity and forming a needle-like convex structure similar to the surface of a lotus leaf. ODA increased contact angle of WRM surface from 0° to over 90°, reaching up to 143° with higher ODA content, though excessive concentrations caused surface cracking. The rise height of capillary water decreased with the increase of ODA content, and 3 % ODA effectively prevented water ingress. Lower ODA percentages were also effective, especially when a secondary layer or heating method was used. In terms of mechanical strength, the internal friction angle and cohesion increased first and then decreased with the increase of ODA, peaking at 1 %. The research results can provide reference for subgrade construction in WRM area and improve utilization rate of subgrade filling.

KW - Microcosmic mechanism

KW - Octadecylamine

KW - Soil-water interaction

KW - Subgrade filling

KW - Water resistance

UR - https://www.scopus.com/pages/publications/105009698372

U2 - 10.1016/j.mtcomm.2025.113273

DO - 10.1016/j.mtcomm.2025.113273

M3 - Article

AN - SCOPUS:105009698372

SN - 2352-4928

VL - 47

JO - Materials Today Communications

JF - Materials Today Communications

M1 - 113273

ER -