Effect of cement kiln dust on the low-temperature durability and fatigue life of hot mix asphalt

Abstract

Cement Kiln Dust (CKD) is a waste material that is considerably produced in a high volume during the cement production process. In this study, the effect of CKD as filler material on low-temperature characteristics of hot mix asphalt (HMA) has been investigated. Laboratory program composed of evaluating the HMA durability against the freeze–thaw cycles using indirect tensile strength test and analyzing the fatigue behavior at four temperatures of 20, 0, −10 and −20°C using a four-point flexural fatigue test. Furthermore, regarding the existence of heavy metals in CKD compounds, environmental evaluation has been carried out by applying toxicity characteristic leaching procedure (TCLP) test. According to obtained results, mixes containing CKD filler demonstrated better resistance against freeze–thaw cycles compared to the control mixture containing limestone (LS). Moreover, mixes containing CKD exhibited higher fatigue life compared to the control mix and for all mixes the fatigue life decreased by decreasing the temperature. However, at lower strain levels of 150 microstrain, the fatigue life of studied mixes were to high extent similar and even higher fatigue life was obtained by reducing the testing temperatures. In addition, the findings of TCLP test showed that the amount of heavy metals in leachate from HMA containing CKD was low and satisfied the required criteria.