Surfactant modified clays' consistency limits and contact angles

This study was aimed at preparing a surfactant modified clay (SMC) and researching the effect of surfactants on clays' contact angles and consistency limits; clay was thus modified by surfactants for modifying their engineering properties. Seven surfactants (trimethylglycine, hydroxyethylcellulose, octyl phenol ethoxylate, linear alkylbenzene sulfonic acid, sodium lauryl ether sulfate, cetyl trimethyl ammonium chloride and quaternised ethoxylated fatty amine) were used as surfactants in this study. The experimental results indicated that SMC consistency limits (liquid and plastic limits) changed significantly compared to those of natural clay. Plasticity index and liquid limit (PI-LL) values representing soil class approached the A-line when zwitterion, nonionic, and anionic surfactant percentage increased. However, cationic SMC became transformed from CH (high plasticity clay) to MH (high plasticity silt) class soils, according to the unified soil classification system (USCS). Clay modified with cationic and anionic surfactants gave higher and lower contact angles than natural clay, respectively.