Currently, a fundamental relation between cohesion and adhesion in cohesive soils has not been established. Yet, it is of great importance to get a better understanding of the relationship between cohesive and adhesive forces, because the large surfaces on dredging tools can generate a lot of resistance, meanwhile limiting the production for materials with increasing adhesion. Because the relationship is not exactly known, the adhesive strength of a clay is usually expressed as a fixed fraction of the cohesive strength, varying between 60% for hard clays and 100% for soft clays. Material tests of cohesive soil have been undertaken to detect the actual relation between the adhesion and cohesion of cohesive soil. The experimental results can directly help the implementation of the Delft sand, clay and rock cutting model, as a result the optimal cutting angle in dredging practice can be calculated. In this way, the designs of dredging tools are improved, which can help to increase the overall production rate in dredging operations. This paper gives detailed description of the experiment setup and results.