REINFORCEMENT AND STABILIZATION OF SAND LAYERS WHEN STRENGTHENING ROADS

The report describes a field trial during the summer of 1988 to test methods of stabilising layers of sand and reinforcing pavements containing layers of sand and basecourse gravel when strengthening a road with low bearing capacity. Twelve test-stretches containing layers of sand have been constructed on the road 881 near sunne in the province of vaermland. One aim of the construction of the test stretches is that they should act as an informatory and preliminary test in an investigation of the possibilities of using sand at a higher level than is allowed at present. A second aim is to test means of reinforcing pavement constructions where, as in this case, a layer of sand is used in the lower part of the basecourse. The test stretches have been built by the national road administration, but have been planned and supervised by the vti (on commission by the national road administration). Planning has taken place in consultation with sgi (the Swedish geotechnical institute) and the company nynaes petroleum. The trial includes stabilisation with cement and bitumen emulsion and mechanical stabilisation with stone dust as well as mesa, a waste product from lime manufacture in a sulphate mill, used as a filler in cement stabilisation. In the stabilisation with cement, a low cement content has been used to minimise shrinkage cracks. Reinforcing has been performed with the reinforcing sheet in different locations in the pavement and geogrids, both geotextile and non-woven geotextile, have been used. On two test stretches, plastic fibers (length 5 cm) have been mixed in the sand. Inspections and measurements of ruttings and bearing capacity are the principal methods used in documentation of the results.