The effect of aggregate gradation and asphalt type on Marshall Properties and permanent deformation parameters of asphalt concrete mixes

Abstract

Rutting of flexible pavement idealizes the main problems of pavement distinguished around the world and especially in Iraq. Rutting of asphalt surface layer may be associated with plentiful reasons during structure period and service period. The main objectives of the research are to estimate the effect of asphalt type and gradation of aggregate on hot mixture asphalt (HMA) rutting potential in asphalt concrete mixes realize the effect of aggregate characteristic on Marshall Mix properties and estimate the relation between mix properties and rutting potential of HMA. Mineral aggregates characteristic have substantial influences in execution of local highway which offers the potential of development in these characteristic to resisting various domain of exterior applied loads and conditions of environmental. The substantial properties of aggregates are gradation impacting on permanent deformation of hot mix asphalt. In this study; Fine, mean and coarse gradation mixtures for different aggregate types were tested to check the influence the different aggregate types and gradation on mix properties. Properties investigated were, Stability and Flow of Marshall, unit weight, voids in mineral aggregate, air voids, and voids filled with asphalt. The results indicated that optimum asphalt content (OAC) and characteristics of Marshall are significant variation different due to aggregate gradation and asphalt type. The optimum asphalt content is minimum in mean  gradation AC(60-70) and AC (40-50) ,The maximum value of stability obtained in the coarse gradation AC(60-70), The flow value obtained is minimum for the mean gradation AC( 40-50). Maximum value of resilient modulus of the mixture in mean gradation AC (40-50) greater than maximum value of mixture in fine gradation AC (60-70) at rate 1.29 times. Finally, the altering of gradation of aggregate and type of asphalt significantly affected the permanent deformation parameters in flexible pavement.