The Effect of Hydrated Lime Additives on Moisture Sensitivity and Overall Performance of Hot Mix Asphalt Mixtures

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Addis Ababa University


Well-designed asphalt mixtures can be expected to serve successfully for many years under a variety of loading and environmental conditions. However, Stripping is one of the common types of pavement failure found in asphaltic pavements. Besides high traffic impact stress, climatic factor such as temperature and moisture have also profound effect on the durability of hot mix asphalt pavements. One of this research’s goal is to evaluate and compare the stripping performance of unmodified and lime modified hot mix asphalt using two different types of lime application. The research study utilized laboratory evaluations to study effects of hydrated lime additive on moisture susceptibility and important physical properties of Hot Mix Asphalt mixtures. The evaluation involved six mix designs from two aggregate sources and one bitumen source. Out of the six, two are used as control and the other four are checked for the advantages of hydrated lime additives. Laboratory testing was accomplished in the first phase with the production of Marshall compacted specimens to determine the performance of Hot Mix Asphalt using Marshall Mix design methods and parameters such as air voids, voids in mineral aggregate, voids filled with asphalt cement, Marshall Stability and flow are measured. The result shows superior advantage on hydrated lime additive on stability and other important physical properties of Hot Mix Asphalt. Beside this, the optimum asphalt content is determined for phase two test. For the selected optimum bitumen content on the second phase, six samples from each mix were prepared to conduct the moisture susceptibility test. Three of the six samples are conditioned with saturation and freeze-thaw cycles and the other three were unconditioned. Finally the tensile strength test for each group was conducted. The tensile strength ratio according to AASHTO T 283 proved that that hydrated lime additive has an advantage on moisture susceptibility The research concludes that adding hydrated lime in Hot Mix Asphalt improves the performance of mixtures and increases the life of highways. Furthermore, both dry lime and lime slurry hydrated lime application methods used in this research have good results compared with the unmodified samples. Key Words Hot Mix Asphalt, Moisture damage, Moisture susceptibility, Stripping, Anti-strip additives, Lime, Marination, Asphalt, Marshall Mix design.



Hot Mix Asphalt; Moisture damage; Moisture susceptibility; Stripping; Anti-strip additives; Lime; Marination; Asphalt; Marshall Mix design.