Evaluation of Performance Characteristics of Gravel Modified with Recycled Asphalt Pavement in Comparison with Crushed Stone Aggregates in Uganda

This study examined the performance characteristics of gravel material when incorporating RAP material and CS aggregates. Gravel samples were sourced from the Kabuuma borrow pit in Munyonyo, RAP aggregates from Bwaise, Kawempe road, and CS aggregates from Sterling Quarry in Mbalala Mukono. Initial characterization involved Proctor tests, Atterberg limits analysis, particle size distribution assessments, and CBR tests for gravel. RAP aggregates underwent sieve analysis, while CS aggregates were subjected to ACV, FI, and sieve analysis. Various combinations of RAP and CS aggregates were added to gravel in percentages ranging from 25% to 45%, and subsequent tests including particle size distribution, Atterberg limits, Proctor tests, and California Bearing Ratio were conducted. Results indicated an increase in MDD values with the addition of RAP and CS aggregates, coupled with a decrease in OMC values. Strength also showed improvement across all percentage additions. Notably, at 45% RAP added to gravel, the CBR value was 36%, compared to 52% when 45% CS was added, indicating CS aggregates were more effective in enhancing gravel strength. Atterberg limits decreased with higher percentage additions; for instance, at 40% CS added, PI value reduced to 15.4% compared to 24.2% with 40% RAP added.