Characteristics of Clay Soft Soil in the Mekong Delta of Vietnam and Improvement Result with Cement

Abstract

The results of research on the characteristics of soft clay soils distributed in some provinces of the Mekong Delta show that most of the soils are contaminated with easily soluble salts, containing organic matter, pH < 7. Sandy clay, clay in An Giang, and clay mud in Tien Giang are less acidic, not salty, and contamination of salts in the form of sulfate- chloride. Clay mud in Hau Giang is less acidic, less salt, and contamination of salts in the form of chloride-sulfate. Clay mud in Bac Lieu and Ca Mau are lots of salty soil, contaminated with chloride of salts. Peat soil in Kien Giang is strongly acidic, not salty, contaminated with sulfate -chloride. All of them have a large compression coefficient, small load capacity, therefore they should be reinforced when construction works. Unconfined compressive strength of reinforced soils with cement showed that sandy clay in An Giang is the best, and then is soft clay in An Giang and clay mud in Tien Giang, Hau Giang, Bạc Lieu, and Ca Mau. Peat soil in Kien Giang has a low strength at different contents and days of age (with a concents 400 kg/m3 at 91 days has unconfined compressive strength qu = 201 kPa), only 12.8 to 23.0% compared to the soil elsewhere. The curing time process samples show that the compressive strength of the peat soil mixed cement is increased initially, then they were decreased over a period of 28 days.