INVESTIGATION OF SALT, ALUM CONTENT IN SOFT SOILS AND THEIR EFFECTS ON SOIL PROPERTIES: CASE STUDY IN COASTAL AREAS OF VIETNAM
Soft soil is widely distributed in Vietnam’s coast area, which normally contains salt, organic matters, and its properties can be affected by the saltwater intrusion. This article presents experimental laboratories to investigate the salt, alum contents in some soft soils distributed in the coastal areas of Vietnam, and their effects on the properties of soft soil. To investigate the effect of salt content and pH values on soil properties, the soil was submerged into different solutions of salt content and pH value for 10 days before testing. The experimental results indicated that the average salt content in natural soils in the studied area changed from 0.31% to 1.58% and had a different level of salt contamination. In some places, the soil had a low pH value (pH<4.5) and high sulfate content. The research also showed that the increase in salt and alum contents caused a decrease in undrained shear strength and an increase in liquid limit and compression index.