USE OF GLASS GRID IN PAVEMENT LAYERS

Abstract

India is a large country with contrasting terrain, weather and environmental conditions and a large area is covered by weak soils like black cotton soils, peaty, clays etc. nl'hesc soils arc not structurally sound to bear the traffic load. It is therefore often required to stabilize and reinforce soil by some method. Different types of materials are being increasingly used in highway engineering to facilitate construction, ensure better performance wed reduce maintenance_ Based on comprehensive experimental programmes undertaken in developed countries non metallic materials may be suitable For reinforcement_ Glass grid is a self adhesive glass fiber reinforcement which has been extensively used in airfield pavenierits_ Highways to arrest reflective cracking. These materials are of three types viz, glass grid-8501, glass grid-8502, glass grid-855Q. They. are anti corrosive, non- biodegradable, resistant to ultra-violet and oxidative effects. In the present study, various laboratory experiments like CBR tests, T'ri- ial tests. Plate load tests and Fatigue 'tests wcrc conducted on unreinforced and reinforced soils to sec the reinforcing effect imparted by glass grid. It was observed that the CBR of soil improves considerably when glass grid is placed in the sample. CBI value of Roorkee soi] is increased by 134° 4 when it is reinforced by glass grid. Maximum increment in CBR is achieved by placing glass grid near the surface of the sample. Similarly tri-axial tests were conducted on soil samples by p]acing glass grid at different heights and with different coy fining pressures. It was observed that confining pressure and position ol` glass grid has an effect on deviator stress. The value of peak deviator stress increases by 32% for the soil reinforced with glass grid. Cohesion value increased b ' 100% and Angle of internal friction increased by one degree. In plate load tests modulus of subgrade reaction and modulus of elasticity values of subgrade soil are improved by 59°%% and 56% respectively by using glass grid at 5 cm below the surface of sub r-ade layer. The study on fatigue tests on unreinforced and reinforced pavement models revealed that, introduction of glass grid layer increases the number of repetitions by two and half times as compared to pavement model without glass grid.