Evaluation of Milk of Lime Effects at Pavement Layers Interface

Asphalt pavements service life is affected by layers debonding. Tack coat can be applied between binder layer and wearing course layer to increase cohesive strength, but its removal by machinery equipment at the construction site is not rare. In order to protect the tack coat from removal, milk of lime can be spread on the latter one and represents a better solution than filler in terms of operability. In this short-paper, milk of lime effect on interface bond strength was investigated and shear bond test (SBT) was selected to characterize the specimens. Two-layered specimens with different amounts of tack coat (partially removed with specific masks) and milk of lime application rates (0, 250, 375, 500 g/m2) were made and tested. The results show that specimens with 0% removed tack coat witness a slight shear strength increase and a notable shear bond energy rise at growing milk of lime application rates. Specimens with 40% removed tack coat reveal an initial shear strength and shear bond energy decrease at 250 g/m2 application rate and an increasing trend at higher application rates. Specimens with 70% removed tack coat show an opposite trend, with an increase at 250 g/m2 and a following decrease. Furthermore, the latter ones show too rigid behavior with 375 and 500 g/m2 milk of lime application rates. Globally, adding the right amount of milk of lime compared to residual bitumen enhanced mechanical properties at the interface for some combinations tested.