APPLICATION OF GEOFARICS IN PAVEMENT SUB- GRADE CONSTRUCTION

CIVIL ENGINEERING

ABSTRACT The purpose of this project is to enhance the sub grade strength by using geofibres. India has one of the largest road networks in the world, aggregating to about 33 lakh km at present. However many of the existing roads are becoming structurally inadequate because of the rapid growth in traffic volume and axle loading. At locations with adequate sub-grade bearing capacity/CBR value, a layer of suitable granular material can improve the bearing capacity to carry the expected traffic load. But at sites with CBR less than 2% problems of shear failure and excessive rutting are often encountered. The ground improvement alternatives such as excavation and replacement of unsuitable material, deep compaction, chemical stabilization, pre loading and polymeric geosynthetics etc are often used at such sites. The cost of these processes as well as virgin material involved is usually high and as such they are yet to be commonly used in developing nations like India. In this context natural fiber products hold promise for rural road construction over soft clay. India is the first largest country, producing coir fiber from the husk of coconut fruit. The coir fiber (50 to 150 mm long and 0.2 to 0.6 mm diameter) till recently were spun into coir yarn and then woven to obtain woven nettings. The fibers are now a day’s being needle punched or adhesive bonded to obtain non woven products or blankets. Geofibre are proving to be cost effective alternative to traditional road construction method. Studies have indicated that the biodegradability of coir can be used to advantage and the coir based geofibre have the potential of being used for rural road construction over soft clay. In paved and unpaved road construction, geosynthetic reinforcement has been applied to improve their overall strength and service life. The stabilization of pavements on soft ground with geofibres is primarily attributed to the basic functions of separation of base course layer from sub-grade soil, reinforcement of composite system etc. But these synthetic products are biodegradable and cause environment problems, whereas natural geofibre like coir is biodegradable. The report presents the results of CBR and plate load test carried in a model test tank simulating rural roads with coir geofibre. The results of the test in the laboratory and the construction of road stretches at 3 locations, with each 100m length are encouraging for use in developing countries (like India) in rural roads that are yet to be developed to connect as many as 0.2 million villages as most of these roads happen to be on soft clay. KEYWORDS: CBR, Geofibre, Geosynthetic Reinforcement, Sub-grade, Biodegradable

This work is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.