Effects of Physical and Mechanical Properties of Soft Soil on Subgrades Performances in Lubuk Bayas Village, Serdang Bedagai Regency

Abstract Generally, the existence of soft soil in Indonesia will be a problem construction highway construction. One factor that influences and needs to known road is characteristics subgrade where pavement placed on it. Poor can cause bumpy surfaces, cracks, or other damage. Therefore, before carrying out improvement, it necessary know its through physical mechanical properties subgrade. This research was conducted Lubuk Bayas Village, Serdang Bedagai Regency, North Sumatra Province. Tests this study include sieve analysis, water content, specific gravity, plasticity limit test, liquid test. The shear strength test California Bearing Ratio (CBR) were carried using Dynamic Cone Penetrometer (DCP). From results testing soil, found Samples 1, 2, 3 fine-grained soils with percentage passing No.200 greater than 50%. USCS classification system shows samples 1 2 are Lean Clay (CL) group, while sample Fat (CH) group. high because PI value >17. Sample obtained c = 0.1299 kg/cm Ø 13.2°, 0.1075 11.2° 0.1275 11.9°. DCP CBR values 5.35%, 4.73% 3.15%. results, seen location has low bearing capacity, so if used as layer, repair first structural damage does not occur future. Soil improvement made by stabilizing natural materials maintain environmental sustainability. Natural sand certain gradations, stone ash, palm shell various materials.