LABORATORY STUDY ON GEOTEXTILE REINFORCED SOIL FOR POOR SUBGRADE

Many pavements have become useless within their design life due to sudden fall in subgrade strength as a result of unforeseen rise in the moisture content of the subgrade which may be due to a rise in ground water level (GWL) or water seeping through cracks on road pavement. Geosynthetic materials have been found worthy to be a good means of reinforcing subgrade by increasing the useful life of a pavement or substantially decreasing the thickness of the base course. Three different soil samples were obtained and were compacted according to West African Standard and CBR tests were carried out without reinforcement (geotextile) and also by placing geotextiles at various depths within the soil mass in single layers. Then the effect of the geosynthetic material (geotextile) was observed. The results show that the strength of the subgrade (laterite) is considerably lowered with increased moisture content; and the introduction of geotextile as reinforcement in the soil substantially increase the soil at all levels (2/5, 3/5, 4/5) with the maximum increase in strength observed to occur at 3/5 level from the base of the compacted soil