Effect of geosynthetic reinforcement pull-out on the surface characteristics of facing blocks

Abstract

The friction coefficient between the facing blocks and the geosynthetic reinforcement is one of the parameters in MSE design. To obtain this parameter, specific tests are foreseen in the standards. However the pull-out process of the geosynthetic reinforcement has an effect on the facing block surfaces. In this study the roughness of the precast concrete block elements was determined before and after the pull-out test to see the effect of the pull-out process, since the frictional behavior is a function of surface roughness. For this purpose 3D scanning was performed on block surfaces and a special macro program was coded to get a surface reading for every 0.5 mm. Since the concrete blocks used in the experiments are produced using the dry-cast method, the surfaces are not smooth and many small sized aggregate particles stick out of the average surface. As a result these extrusions break during the pull-out test. Hence, in conclusion, the roughness values have always increased after pull-out tests for both geotextile and geogrid reinforcement.