A PARAMETRIC STUDY ON REINFORCED FLYASH IN HIGHWAY EMBANKMENTS

Abstract

Provision of new traffic lanes and grade separated intersections require large quantity of material for construction of embankments as well as roads and also large investments if the conventional methods of construction are used. The alternative is to use low cost techniques by using industrial wastes like flyash, available enormously and almost at free of cost which otherwise cause environmental and disposal problems. In India, efforts have been made since the early seventies to utilize this waste product in different fields, but unfortunately nearly 5% utilization has been achieved till date which is far below the world average of 16%. Efforts have been made for maximum utilization of flyash in embankment construction in bulk quantities. It is often required to stabilise and reinforce the structurally unsound soil to bear the traffic load. Different types of materials are being increasingly employed in highway engineering to facilitate construction, ensure better performance and reduce maintenance. Based on comprehensive experimental and research programmes undertaken in developed countries non-metallic materials may be suitable for reinforcement. Geotextiles are the development in the field of reinforcing materials. These materials are thin, bi-dimensional, flexible, anti-corrosive and non-biodegradable hence have a long life. In the present study, a series of plate load tests and field CBR tests were conducted on locally available Roorkee soil (SP), flyash, flyash in combination with lime and flyash combined with Roorkee soil (SP). These tests were conducted on the above materials with and without geotextile reinforcement to see the reinforcing effect imparted by geotextiles. The geotextile reinforcement was also kept at varying depth and the tests were conducted. it was observed that the CBR of the above materials improved when geotextile was placed in it. Maximum increment in CBR was achieved when geotextile was placed near the surface. The introduction of geotextile reduced the deformation and increased the bearing capacity as was revealed by plate load tests.