The Performance of Conventional and Polymer Modified Bituminous Mixture Containing Different Types of Sand as Fine Aggregate

Roads are the heart of any nation’s economic and social integration but due to different distresses on it like fatigue and rutting, a number of research have been carried out on modifying the bituminous mixtures to bring real benefits to highway performance in terms of better and longer lasting roads and savings in vehicle operating cost (VOC). Material properties play an important role in determining the final characteristics of the mixture and its performance. This study looks at the incorporation of different types of fine aggregate into bituminous mixtures to predict the performance of the bituminous mixture that related to fatigue and rutting, where both conventional bitumen penetration 50/60 and 80/100, and polymer modified bitumen PM1_82 and PM1_76 and PM2_82 and PM2_76 were used. PM1 is consisting of styrene butadiene styrene (SBS), while PM2 is consist of one of the plastomers polymer. Physical, chemical and mechanical tests were performed on the different types of sand to determine their effect when incorporated with a bituminous mixture. A series of extensive laboratory test programs were carried out. The tests conducted include; the Marshall Test, the creep test, wheel tracking test and beam fatigue test. Results from the Marshall Test showed that fine aggregate characteristics influence the optimum bitumen contents, workability and other engineering properties such as stability, density and stiffness. The results of the performance tests indicated that the resistances of the mixtures with quarry sand against rutting and fatigue damage were superior to those of the other sand mixtures. This was followed by mixture containing river, mining and marine sand respectively. This may be due to the physical, chemical and mechanical properties of the sand, as quarry sand exhibited greater angularity, rougher and it has bigger particles and higher shear strength and higher content of alumina (Al2O3) and hematite (Fe2O3). Polymer modified bitumen mixtures reveal more resistance to rutting and fatigue than the conventional mixtures. Polymer modified mixtures PM1 was found to offer the highest resistance in rutting followed by the polymer modified mixtures PM2, 50/60 and 80/100 penetration bitumen mixtures respectively. While in fatigue resistance polymer modified mixtures PM1 also exhibit the best fatigue performance followed by PM2, 80/100 and 50/60 penetration bitumen mixtures respectively. This may be due to the PMB having better viscosity property than that of the conventional binder.