A STUDY ON GEOTECHNICAL CHARACTERIZATION OF RED SOIL OF DHAKA CITY OF BANGLADESH

Generally red soils characters are different from other soils. In Bangladesh, a very few red soils are characterized in geotechnical point of view. However, it is necessary to massive study on it. From this point of view, a study has been undertaken to characterize the red soils from their properties which assist the engineer for design of structure of foundation on red soil and same strata of red soil in other area. From this study the iron concentration have been found about 27.8% for red soils with 38% clay whereas soils with 4% clay contain iron concentration of about 12.9%. That is soils containing high percentage of clay have more iron and manganese concentration in compare with soils containing low percentage of clay. The pH values have been varied from 5.6 to7.026. It indicates the soils are strongly acidic and sometime it is neutral. The natural moisture content varies from (8.90-28.99)% whereas plasticity ranges from (28-32)% and shrinkage limit varies from 7% to 22%.The consistency ranges from stiff to very stiff and the red soils have contained particles sand (12-25)%, silt (39-49)% and clay (26-39)%. The dry density of these soils varies from (14-16) kN/m 3 and the specific gravity of the cohesive soil varies from (2.675-2.684) and of the non-cohesive soil varies from (2.642-2.653). The study finds that the natural moisture content is not adequate to fulfill engineering needs. Plasticity as well as stiffness of red soil should also be considered to draw engineering attention for construction works.