Optimum Gum Arabic Content as Bitumen Modifier in Hot Mix Asphalt.

Roads in Nigeria and like any other developing country are hugely plagued with deterioration and damage due to excessive traffic beyond design load, environmental conditions and their interactions as well as low budgetary allocation for routine/preventive maintenance. In order to address the problems, researchers/practitioners in the highway community have engaged in the use of admixtures and waste material to enhance the properties of paving materials while reducing the cost of production. This study investigates the suitability of Gum Arabic (GA) also known as acacia gum to be used as bitumen modifier in Hot Mix Asphalt (HMA). GA is a natural material consisting or hardened sap of various species of acacia. Its glue or binder property makes it a potential material for use as a modifier in HMA. In order to determine the performance of asphalt concrete mix containing GA as modifier, 0%, 2.5%, 5%, 7.5% and 10% GA (by weight of bitumen in asphalt concrete mixture) were added at bitumen contents of 4.5%, 5.5%, 6.5% and 7.5% each. Marshall parameters (stability and flow) and volumetric properties of the asphalt mixtures were used to evaluate the performance of GA as modifier and determine the optimum GA content. The study revealed that asphalt concrete mixture prepared using 2.5% GA at a bitumen content of 6.5% performed better than the control sample (0% GA content) based on the evaluation parameters. This can be recommended for use in surfacing of heavily trafficked flexible pavements. [ABSTRACT FROM AUTHOR]