THE SWELLING POTENTIAL OF THE SOILS FROM IASI AREA, ROMANIA

The soils with swelling potential (S) are a constant problem in engineering construction. These types of rocks show significant variations in volume in response to changes of the moisture content in their structure. One consequence of these changes in volume is the occurrence of significant damage in various types of industrial and civil construction. The aim of the study was to identify the swelling potential parameter for a total of 20 samples of clay, taken from different outcrops in Iasi area, Romania. The parameter was analyzed based on the direct method, according to technical regulations in force at the moment (STAS 1913/12-88). The method consists in determining free swelling potential in the laboratory. This research was done in order to extend the known areas where soils are proven to be expansive and to make a comparison between the swelling potential values of the bedrock and also for the shallower deposits. The two categories of deposits are making the difference between the soils with favourable behaviour (bedrock) or unfavourable (superficial deposits) from a geotechnical point of view. The results of this research point out that almost all soils, from the investigated outcrops, have a high swelling potential, with values greater than 70%. S (for 13 samples) and very high figures, greater than 140 % S (for two samples). The results of the other five samples show values below 70% S. It has been observed as well that in lowlands and in terrace areas or at the contact between these two active swelling soils are present. The study confirms also that bedrock and superficial deposits have high and very high expansive potential. Extending and completion of the study will be made later by analyzing new soil samples and by applying other methods.