Cement and animal bone powder on rheological characteristics of bitumen
The developed countries have adopted the use of modifiers for assessment of asphalt binder long term performance. Asphalt contributes 90 to 95 % in cost estimation of Flexible pavement while compared to all other major material components. Since Ethiopia is one of the landlocked country without any fossils fuel source for the production of Asphalt, moreover Ethiopian importer depends on neighbour country Djibouti. This research analyzes the effect of modifiers on the rheological characteristics and also considers fatigue resistance with the main aim of preventing rutting in asphalt pavement due to different temperatures. Hence a seminal effort is assessed in evaluation of Portland cement and Waste Animal Bone as cost effective modifying agents. The conventional bitumen penetration grade (80/100) is used in this research. The control specimen four binders were obtained by mixing the asphalt binder with four different percentages (0 %, 1 %, 3 % and 5 %) of PCWAB by weight of asphalt binder. Rheological characteristics were evaluated with Dynamic Shear Rheometer test (DSR) such as Amplitude sweep test (AST), Frequency sweep Test (FST) and Multiple-stress creep and recovery test (MSCR). AST and FST were adopted for determining linear visco-elastic range, Master curve were developed for same temperature (21.1 °C, 37.8 °C, and 54.4 °C) respectively while MSCR and Performance Grade (PG) were determined for four different temperatures (52 °C, 58 °C, 64 °C, and 70 °C). Finally, the master curve shows that 3% and more addition of PCWAB on asphalt binder increases the stiffening property of asphalt binder at high temperatures and low loading frequencies (susceptible for rutting). On the other hand, from the test result obtained from MSCR test the smallest total strain value was 5 % for PCWAB followed by the 3 % and 1 %. Thus, up to 3 % addition of PCWAB significantly improves the resistance of asphalt binder to rutting. In addition, using PCWAB as asphalt binder modifier has a positive impact on environmental preservation. The performance grade determination also depicted the improvement in PG as content of modifier increases. Therefore, the evaluation showed that the 3 % modified binder is better in its rutting performance with improved performance grade.