Evaluation of Laboratory Aged Bituminous Mixes Containing Hydrated Lime

The effects of hydrated lime in bituminous mixes have been studied by various researchers. It is known that hydrated lime increases the mix stiffness and adds to its resistance against stripping. On the other hand، upon ageing of mixes these become too stiff and get prone to cracking. The ageing characteristics of mixes containing various amounts of hydrated lime have been studied in this research. Slab samples were aged at 85oC for 120 hrs according to AASHTO PP2 standard procedures. Then the mix characteristics were analyzed by performing beam fatigue testing on beams that were cut from the slab aged samples. It was shown that the fatigue resistance of mixes increases with increasing the amount of hydrated lime. However، this was limited to 1. 5% of hydrated lime. the addition of more lime resulted in sharp decrease of fatigue resistance. Analyzes of mixes using dissipated energy concept confirmed that 1. 5% hydrated lime was the optimum amount of this active filler to be added to bituminous mixes.