SWELLINGPHENOMENS IN SOILS AND ITs ,EFFECTS ON THEIR PHYSICAL AND ENGINEERING PROPERTIES

Abstract

The simplest definition of the swelling phenomena is the increasing in volume of the soil on wetting by the water or moisture that means the heaving in the soil which is occurring in such a conditions they are; texture of the soil, hydrology and mineralogy. The experimental testing of volume change for the seven selected samples reveals that the volume change (swelling) had been taken place in all of them in different values due to different reasons, where the samples A1 and A4 have the same value which is (20 ml.) and the samples A2 and A7 have (15 ml.) both of them and that is due to presence of clay and silt fractions, relatively, in a high percentages respected with the sand fractions in the samples A1 and A2, while in the samples A4 and A7 the volume change is may due to presence of very fine materials (tenderness of substances) of sand, fine silt with clay fractions. The samples A5 and A6 have the minor value of the volume change reaches to (5 ml.) in both of them and that is due to presence of sand fractions in a very high percentage reaches to (93%) and (92%) respectively, with a little percent of clay and silt fractions. The results of volume change reveal that the swelling is taking place when their conditions have been gotten, whether presence of clay fractions or presence of very fine sand and silt fractions (tenderness of substances), or colloidal materials, where the latter is one of the conditions of occurrence of the swelling phenomena. Most of the (34) samples are considered to be (Inactive class) according to Skemtonʼs classification, and the degree of the expansiveness of them are as follows; (10) of them are non- expansiveness, including the (4) non-plastic, (19) of them are medium expansiveness and (5) are high expansiveness, and that refers to the soils are considered to be, primarily, stable or slightly in volume change.