The objective of this lab is to determine the relationships between shear stress and horizontal displacement, and between vertical compression and horizontal displacement. The direct shear test can be performed on both cohesive and cohesive less soils and it evaluates both cohesion c and angle of internal friction. These parameters are used to evaluate a soil's shear strength. This test is performed to determine the consolidated-drained shear strength soils. The shear strength is one of the most important engineering properties of a soil, because it is required whenever a structure is dependent on the soil's shearing resistance. The shear strength is needed for situations such as determining the stability of slopes or cuts, finding the bearing capacity for foundations, and calculating the pressure exerted by a soil on a retaining wall. To perform the test, soil is placed in a two-piece brass box constructed so that the top and bottom half can slide relative to each other. In the direct shear device, a normal force is applied to the loading head and ball above the soil by air pressure. The applied force in pounds is determined by multiplying the air pressure