Research on the material compositions of Holocene clayey soils distributed in Quang Tri and Thua Thien Hue plain

The Quaternary stratigraphies of the coastal plains in Thua Thien Hue and Quang Tri provinces consist of various types of soft soils and among which, dark coloured-organic soils of Phu Bai and Phu Vang formation (ambQ21-2pb, ambQ22-3pv) are characterized by high organic content and compressibility, low bearing capacity and shear resistance and therefore are condisered as one of the weakest components of the soil profile in the regions. In addition to the changeable thickness and distribution depth, Holocen clayey soils spread nearly continuous and in most areas, they extend close to the ground suface. In this paper presents the result of studying the material compositions of clay mud and silty clay mud consituting Phu Bai formation and Phu Vang formation. The clay minerals comprising of Illite (12 - 31%), Kaolinite (4 - 20%), Chlorite (6 - 8%) and Quartz is the main composition of crude dispersions (24 - 61%). The organic content of clay mud and silty clay mud change from 2,26% to 11,4%. Meanwhile the chemical compositions are mainly composed of SiO2 (51.15 – 67,81%), Al2O3 (13,99 – 21,26%) and MKN (6,08 – 14,17%)