LOAD CARRYING CAPACITY OF REINFORCED POND ASH BEDS

Abstract

ABSTRACT It is required to increase the usage of coal ashes. Pond ash is the waste product of thermal power plants. Pond Ash is a non-plastic cohesion less material that can be used as a fill material in Geotechnical structures like retaining wall, embankment. Soil reinforcement technique is used for improvement of poor soils. Geo-textiles, Geo-grid sheets, Metal strips, Synthetic geo-textiles, Natural geo-textiles, at random distribution used as reinforcing materials to the soil. The soil reinforcement causes important improvement in shear strength, physical property, bearing capacity and economy. Soil reinforcement is an easy technique for ground improvement. Experimental study is going to be done using geo-textile and sand layer. The geo-textile layers are placed at different depths from top of the mould. By the suitable reinforcement the strength of the compacted pond ash fills can be retained partially. The compacted pond ash beds are reinforced with fibreglass sheet. The position of the reinforcement, the number of layers of reinforcement and overlain sand layer thickness was varied. In first set of experiments a series of California bearing test (CBR tests) were conducted on pond ash beds reinforced by fibreglass sheet. The CBR values of these specimens were found out and these are compared with that of the unreinforced pond ash bed compacted to MDD at OMC. In second set of experiments the CBR value of compacted pond ash beds overlain by sand layer compacted to different relative densities and different moisture contents are evaluated. After a series of CBR test on pond ash beds reinforced by fibreglass sheet and pond ash beds overlain by sand layer, it can be concluded that with the increase in depth of reinforcement the CBR value decreases. When the depth of reinforcement is 2 times the diameter of the plunger, practically there is no improvement in the CBR value of reinforced pond ash. When the number of layers of fibreglass reinforcement increases; the CBR value of reinforced pond ash beds increases. CBR value increases with the increase in thickness of overlain sand layer, so the CBR value of compacted pond ash can be improved by putting a layer of sand over it. When the water content of sand layer increase; the CBR value of reinforced pond ash beds increases.