Modeling of Resilient Modulus of Korta Reinforced Asphalt Mixtures Using Response Surface Methodology (RSM)

In this paper, two models have been developed to predict the resilient modulus of asphalt mixtures reinforced with Korta fiber subjected to square and haversine waveform, based on the response surface methodology. To this end, the asphalt mix samples were fabricated with three different percentages of bitumen and four different percentages of Korta fiber and then the resilient modulus was measured at five temperatures, five loading frequencies and two loading waveforms (squared and haversine), using UTM 30 apparatus. In this study, temperature, loading time, bitumen percentage and fiber percentage were considered as inputs variables and the resilient modulus under haversine and square loading waveforms was considered as output variable. The results of this study show that the response surface methodology is able to predict the resilient modulus of fiber reinforced asphalt samples with high accuracy, so that the regression coefficient of the developed equations for the haversine and square loading waveforms is 0.9795 and 0.9777, respectively. Also, the results of the sensitivity analysis show that increasing fiber percentage to a certain amount increases the resilience modulus and increasing the fiber content to more than this percentage, decreases the resilient modulus. This study also shows that the optimum percentage of Korta fiber depends on the bitumen content in the asphalt mix. So that in asphalt mixtures with higher bitumen percentages, the optimum fiber percentage was less (about 1 kg/ton) and in mixtures with lower bitumen percentage, the optimum fiber percentage was higher (about 1.5 kg/ton).