STUDY ON THE SUITABILITY OF RECLAIMED ASPHALT PAVEMENT AGGREGATE (RAPA) IN HOT MIX ASPHALT PRODUCTION
The main objective of this study was to evaluate the suitability of recycled asphalt aggregate with fresh aggregate in hot mix asphalt production by using experimental laboratory investigation. Also, Non-probable sampling techniques were adopted to collect a sample. The engineering properties of extracted Reclaimed asphalt pavement aggregate and the fresh crushed aggregate were identified based on standard specification before starting the Marshall Mix design, Then the Marshall Stability test was conducted on crushed aggregate with three different aggregate gradation sizes 5.0%, 5.5% and 6.0% by weight of aggregates and with five different bitumen content 4.0%, 4.5%, 5.0%, 5.5% and 6.0% by weight of total mix. Depending on the selected aggregate gradation Marshall Stability test was conducted for reclaimed asphalt pavement aggregate with a replacement rate of 5.0%, 15%, 25%, 35%, 45%, 55%, and 65% by weight of crushed aggregate to determine its optimum bitumen content according to National Asphalt Pavement Association method (NAPAM). A total of 64 mix designs and 190 specimens were prepared. Hence, Marshall Stability and Moisture Susceptibility test with 3-trials, hence rutting test with 2-trials. From 190 specimens, 45 were for the control mix, 105 were for replacement proportion, 36 were for Moisture Susceptibility and 4 were for Rutting Based on the Marshall Test results and their performance tests such as Moisture Susceptibility and Rutting was performed to maximum allowable replacement percentage was compared with standard specification. The optimum bitumen content result obtained in percent was 5.1, 5.04, 4.98, 4.87, 4.81, 4.74, 4.67 and 4.53 for 0 % (control), 5.0%, 15%, 25%, 35%, 45%, 55% and 65%, respectively. The experimental value of Tensile Strength Ratio, proportional rut depth and mean rut depth on 45% RAPA replacement was 85.42% and 4.48 %, 2.24 mm respectively. Finally, the test result obtained from the marshal stability and the performance testes indicates that up to 45% replacement of aggregate is reclaimed asphalt pavement aggregate in hot mix asphalt production satisfies the standard specification.
Keywords: Reclaimed asphalt pavement; Marshall Test; Crushed aggregate; Tensile Strength Ratio; Proportional rut depth.