Engineers particularly in advanced nations have been using modified binders to improve the performance of flexible pavements. They use different modifiers to augment the rheological properties of asphalt binder. And specification is done by applying superpave binder grading system which requires performance-based binder tests. In Ethiopia while one of the major pavement distresses is rutting, there is no substantial effort to minimize this high temperature distress by using modified binder of improved visco-elastic property, in addition the binder grading system does not comprise performance-based tests. This thesis was conducted by performing a number of laboratory tests on virgin and modified asphalt by adding ESP by weight of asphalt to evaluate the rheological property of asphalt bitumen. Three percentage of egg shell powder was investigated (3%, 6% and 9%) by weight of bitumen with three samples for each percentage. For both RTFO aged and unaged asphalt binder for conventional tests addition of ESP has decrease the penetration and ductility value however when the bitumen become aged at 9% ductility values are not under the desired value which is stated in ERA 2013, whereas softening point value become increase as ESP content increases. The rheological binder tests were conducted on both RTFO aged and unaged binders for both original and ESP modified bitumen. The LVER of all samples were determined with the help of AST test at 10°C, 21.1°C, 37.8°C, and 54.4 °C. And the limiting strain was 0.38% which was used as an input for FST. Amplitude sweep test was conducted on RTFO aged and unaged bitumen by using a Dynamic Shear Rheometer (DSR). From the frequency sweep test (FST) result, the master curve shows that addition of egg shell powder (ESP) improves the behavior of asphalt binder. Addition of 3% and 6% modified asphalt binder increases the stiffening property of asphalt binder at high temperature and low loading frequency as compared to 9% ESP modified binder for unaged asphalt binder. From the performance grade test, the result shows that improvement of performance grade from PG58-YY to PG64-YY for both unaged and RTFO aged bitumen with the additions of 3%,6% and 9% ESP. The rutting performance improved as showed from MSCR test having lower total strain, lower non-recoverable creep compliance (Jnr) and higher Percent recovery for ESP modified binders.