A Sanding Technique to Improve the Pullout Behavior of Geogrids

In this study, an original application called as sanding, which is based on the coating of conventional geogrids with the help of granular soil material and synthetic resin, is proposed to enhance the soil geogrid interaction by the way of improvement of surface roughness. For this purpose, the series of pullout tests performed on geogrids whose smooth surfaces have been roughened by three type of sanding material (fine, medium, and coarse) under three levels of axial load, to investigate the stripping resistance inside poorly graded sand and well graded sand. Extruded and woven types of conventional geogrids were used as in sanded and ordinary forms. According to the results, it has been proven that two-folded increase levels can be achieved in pullout capacity thanks to the sanding technique, while the grain size of the sanding material is the most important parameter used to prevent stripping. Although, sanded extrude specimens showed more ductile and stronger behavior in terms of tensile strength and related strain, woven specimens were negatively affected due to excessive stress formation in the jaw region of test equipment. Therefore, sanding technique can be preferred within the aim of improve the soil–geogrid surface interaction and increase the pullout resistance of geogrids rather than tensile strength required areas. As a result, the design length of usual geogrids can be shortened in critical sections of projects by this way.