EVALUATION OF REINFORCED FLEXIBLE PAVEMENT

Abstract

The idea of reinforcing flexible 'pavements has existed for some years whereas reinforcement by the use of geosynthetics have practically invaded the Civil Engineering industry recently. In present day situations where energy saving, cost saving and time saving techniques are preferred, the use of geosynthetics is believed to play an important role in various Civil Engineering works. Geosynthetics such as geogrids and geotextiles with good tensile strength contribute to the load carrying capacity and the stability. of the earth structures viz roads and earthen embankments over soft subgrade. In the present investigation an attempt has been made to see the effect of geogrids on load carrying capacity of flexible pavements when used at different levels. For that purpose laboratory tests such as triaxial tests, shear tests were conducted on aggregates with their maximum size limited to 25 mm by placing the geogrid at different heights. The laboratory test results indicate that intrinsic friction developed, increases in case of reinforced composite structure of flexible pavement and the angle of internal friction decreases with the increase in normal stress. The strength of subgrade was observed to increase with confining pressures when geogrid was placed at 2/3 H from bottom in case of triaxial tests. Further, semi field pavement models of WBM type with and without bituminous surfacing were laid iii and geogrid CE121 placed at interfaces of two layers. Plate iv load tests were conducted on these pavements using 30 cm diameter plate and pressure distribution over the subgrade was observed by placing pressure cells at subgrade level. Comparative evaluation of two types of pavements, reinforced and unreinforced was carried out and the results show that pavements reinforced with geogrid CE121 can carry more loads and for the same load intensity settlement gets reduced by 50%. The conclusion was that these materials did indeed offer potential and should be further evaluated