Clay coating formation on impermeable materials: deposition by suspension retention

The formation of illuviation clay coatings was investigated by passing clay suspensions through columns of coarse quartz sand. Following drainage and drying, suspensions retained on sand grain surfaces formed clay coatings with a high degree of optical orientation. Results suggest that the dominant clay deposition mechanism involved the retention of suspensions on sand surfaces by capillarity and adsorption forces. The results show that the formation of optically-oriented illuviation coatings can result from the flow of clay suspensions within initially wet soil materials.