Laboratory comparison of mechanical properties of emulsified cold recycled asphalt containing cement kiln dust and steel slag with recycled asphalt containing cement

Cold recycling is one of the methods of pavement rehabilitation, which has become popular in recent years. One of the advantages of cold recycling is that its operations are performed at ambient temperature. However, there are still some concerns regarding the use of emulsified cold recycled mixtures. These pavements are susceptible to problems such as raveling, stripping, low initial strength, and long curing time, which are often countered by the use of additives. In this study, the mechanical behavior of the mixture recycled with emulsion bitumen containing cement kiln dust as a waste from the cement production process and steel slag as a pozzolanic waste were compared with the non-additive mixture and the mixtures with 1% and 2% cement content (as a conventional emulsified cold recycled mixture additive). To evaluate the mechanical properties, Marshal stability, indirect tensile strength, resilient modulus and fatigue test were performed on the samples of different ages at different temperatures. The results showed that the combined use of cement kiln dust and steel slag improves the mechanical properties, especially after prolonged curing periods. In some cases, this improvement was even greater than the improvement resulting from the addition of cement. The fatigue test results showed that the mixture containing the new additive had a better fatigue behavior than the non-additive mixture and a comparable behavior with the cement-containing mixture specially at lower strain levels.