Abstract
ABSTRACT The influence of hydrated lime on moisture susceptibility of asphalt mixture was assessed using a combination of surface energy measurements and modified saturation ageing and tensile stiffness test. Four aggregate types, which are commonly used for manufacturing asphalt mixtures in the UK have been selected. These aggregates were from various rocks across the UK which includes felsic intrusive, calcite sedimentary, mafic extrusive and argillaceous sandstone rock sources. Two out of four aggregate sources including felsic intrusive, and argillaceous sandstone showed improvement with the hydrated lime replacement, however the performance of aggregates from calcite sedimentary, mafic extrusive rocks remained unaffected. Mineralogy test results, showed significant differences among four aggregate types used in this study. The difference in the behaviour of four aggregate types to the hydrated lime replacement can be credited in part to mineralogical composition of different aggregates. The hydrated lime content of 1% was observed better than 2% in the aggregates who showed improved performance with the use of hydrated lime. The trends obtained in the surface energy measurements have been found similar to saturation ageing and tensile stiffness (SATS) test technique. The results clearly illustrate a close agreement between both techniques used in this study for the evaluation of moisture susceptibility.
Highlights
Hydrated lime (HL) has been used as an additive in asphalt concrete for a number of years (Kennedy 1984; Lesuesur 2010) starting in the 1970s in the United States due to a decline in bitumen quality due to the petroleum crises in 1973
By looking carefully at the results for aggregate A it can be seen that the type A aggregate used in this paper is not of poor quality in terms of field performance, it has shown some improvements in terms of moisture damage performance with the addition of HL
There has been a considerable difference observed in the mineralogy of all four aggregates used in this study based on Mineral liberation analysis (MLA) results
Summary
Hydrated lime (HL) has been used as an additive in asphalt concrete for a number of years (Kennedy 1984; Lesuesur 2010) starting in the 1970s in the United States due to a decline in bitumen quality due to the petroleum crises in 1973. Extensive research on the use of HL has been carried out over the last 40 years in the US and its use is not limited to being an additive against moisture damage (Lesuesur 2010; Little and Petersen 2005). HL has proved to be a multifunctional additive which improves functional related properties of asphalt mixtures. It is considered as an active filler which improves moisture damage resistance, reduces chemical ageing in bitumen, and stiffens the mastic more than a normal mineral filler, while having no negative effect on resistance to thermal cracking (Lesuesur 2010; Little and Petersen 2005; Sebaaly et al 2006)
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