USE OF FLY ASH AS MINERAL FILLER FOR BITUMINOUS PAVING MIXES

The increase of crude oil prices in recent years resulted in an increase in bitumen prices as crude oil is origin for bitumen, asphalt & in other hand the fly ash from the power generating plants causes severe disposal problems. The main purpose of this project is to study the possibility of using fly ash as mineral filler in Bituminous paving mixes where in general cement, stone dust are used. Fly ash obtained from Dr.NTTPS, Vijayawada, AP has been used in this present experimental work. Coarse aggregates of sizes 40mm, 20mm, 10mm, 6mm available at the crusher units nearby Ibrahimpatnam are used. For comparison, stone dust also used to prepare control mix. Marshall stability test is employed to determine the properties like stability, flow value,% air voids, voids in mineral aggregate(VMA), voids filled with bitumen(VFB) for a Dense Bituminous Macadam(DBM) mix of Grading I. The experimental work is carried out by using specifications from MORTH(Ministry of road transports & highways, specifications for road & bridge works,5 th revision).By replacing the stone dust with fly ash at the levels 4%, 8%, 12% the results are compared. The variation of properties, optimum bitumen and fly ash contents are evaluated. It is observed that the mixes with fly ash as filler not differ much in properties when compared with control mix and satisfy desired criteria specified by a much higher margin. Hence, it has been recommended to utilize fly ash wherever available, not only reducing the cost of execution, but also partly solve the fly ash utilization and disposal problems.