CBR Improvement of Clayey Soil with Geo-grid
The quality and life of pavement is greatly affected by the type of sub-grade, sub base and base course materials. The most important of these are the type and quality of sub-grade soil. But in India most of the flexible pavements are need to be constructed over weak and problematic sub-grade. The California bearing ratio (CBR) of these sub-grade have very low, it needs to more thickness of pavement. Decrease in the availability of suitable sub base and base materials for pavement construction have leads to a search for economic method of converting locally available problematic soil to suitable construction materials. The present research have to study the effect of geo-grid reinforcement on maximum dry density (MDD), Optimum Moisture Content (OMC), California Bearing Ratio (CBR) and E-Value of sub-grade soil. The clayey type of soil and one type of geo--grid were selected for this study. From the study it is clear that there is considerable improvement in California Bearing Ratio (CBR) of sub-grade due to geo-grid reinforcement. In case of without reinforcement (Geo-grid) the soaked CBR value was 2.9% and when geo-grid was placed at 0.2H from the top of the specimen the CBR increases to 9.4%.
Effect of geogrid reinforcement on flexible pavements
Effectiveness of geogrids in flexible pavement reinforcement was investigated throughout laboratory testing and finite-element analysis (FEA). The laboratory testing involved routine material characterization, resilient modulus testing, and five pavement prototype sections. These sections consisted of a 5 cm asphalt concrete (AC) layer, 15 cm granular base layer, and a 30 cm clay subgrade. The base layer was reinforced with a single layer of uniaxial geogrid placed at four different positions within the base layer. The pavement sections were loaded with a static plate-loading equipment and the results were compared with the control section (CS), which had no reinforcement. Results from this study showed that geogrids can be used to reduce tensile stresses in flexible pavement systems. The optimum position of the geogrid reinforcement to reduce tensile strains was found to be directly underneath the AC layer then within 33–50% of the granular base layer height as measured from the bottom of the base layer.
Polymer grid reinforced pavement on soft clay grounds
Abstract This paper deals with model and field tests for investigating the mechanism of reinforcement by a polymer grid in suppressing non-uniform settlement of pavements constructed on soft clay ground. A series of laboratory tests on reinforced and unreinforced model pavements in a soil tank indicates that the polymer grid is useful for suppressing non-uniform settlement of pavement under cyclic loading. Deformation analysis by FEM is carried out to make clear the reinforcement effect of a polymer grid in a model pavement. To investigate the performance of a polymer grid in practice, a test road of 300 m length with six sections of different kinds of pavement is constructed on soft clay ground. The function of a polymer grid is discussed by comparing the pavements made by conventional and reinforced methods.