Characterization of Fly Ash Bituminous Concrete Mixes

Abstract

Fly ashes were collected from 14 thermal power stations located in different parts of India and were characterized using simple tests like fineness modulus, specific gravity, Rigden voids, German filler test and methylene blue value test, and advanced tests like X-ray diffractometer, scanning electron microscope, and chemical analysis. These fly ashes were divided into four groups based on the above tests and then used as filler in bituminous concrete (BC) mixes. The stone dust, a conventional filler in India, was also used for comparing the results. Rheological properties of filler-bitumen (F/B) mastic prepared at different F/B ratios were determined from softening point test, viscosity test, and dynamic shear rheometer test. Strength and durability tests like Marshall stability, retained stability, tensile strength ratio, and static creep tests were conducted on BC mixes with five types of fillers and the results are analyzed and compared. The study indicated that all the four groups of fly ashes are suitable for use in BC mixes with fly ashes in group 4 having the best performance. The optimum filler content is 7% and properties of fly ash BC mixes are better than those of conventional mix.