Abstract :Recently, there have been many studies to decrease environmental pollution around the coal-fired power stations. One of the studies addresses that untreated ash particles cause economic gains for polymer based composites. In this study, free vibration characteristics of bottom ash/epoxy composite beam with respect to 5 and 10% bottom ash additive is considered for possible structural and infrastructural applications. General microstructural methods are handled for bottom ash/epoxy composites, and the modal and stress behaviors of the composites are calculated. Effect of natural frequency on shear stress and Strain energy density at the free edge is examined. Results are given in tabular and graphical forms. Experimental and numerical computations indicate that (i) values of natural frequency of bottom ash/epoxy composites are higher than that of epoxy, (ii) values of damping ratio of bottom ash/epoxy composites are lower than that of epoxy, (iii) shear stress and SED increase with increasing mode number for all bottom ash/epoxy composites.