Identification of dominant parameters for stripping potential in warm mix asphalt using response surface methodology

In this study, response surface methodology was utilized for creating a continuous response function and optimization of effective variables to improve the tensile strength ratio, as an indicator of stripping potential, using factorial experiment with center composite design. The polynomial regression model equations were proposed based on the regression coefficients calculated for the indirect tensile strength in dry and saturated condition as well as tensile strength ratio. Statistical analyses indicated that all first and second orders plus interactive terms were statistically significant with 90 % confidence level except for interactive terms of bitumen–Sasobit content in tensile strength ratio, and grading-Sasobit content in dry indirect tensile strength. Furthermore, it was found that all first, second and interactive terms were statistically significant for saturated indirect tensile strength.