The application of geosynthetics and different backfilling materials used to reinforce forest dirt roads on soil with poor bearing capacity

The difficulties with using forest transport routes on marshy areas induced the authors to search for new technological solutions in building roads surfaces. Using geosynthetics in roads building is more and more common. That is why it was decided to use these materials to strengthen roads surfaces structures on soil with poor bearing capacity. Seven experimental sections in the Forest District Siemianice have been carried out using the geotextile and the geogrid as well as various building materials like: washed gravel, fine sand, road metal, broken stone mix and blast furnace slag. The aim of this work was to assess compressive strength of roads surfaces made by materials described above, situated on the low-compressive strength natural ground. The invesigation was performed directly after the sections had been built as well as after half a year of usage. The analyses of result showed that the road metal and the blast furnace slag were the best building materials among the tested ones. Wherealse the fine sand and the washed gravel were the worst. Modules carried out during researches did not fulfill criteria of compressive strength coming up to surfaces. Researches proved small differences between modules made by the geogrid on the geotextile and surfaces situated on the geotextile only. It was also observed that after half a year of using this road its compressive strength expressed in modules was a little bit lower.