Browsing by Author "Adams, Frank"

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    The role of hydrated lime in reducing stripping and deformation in Hot Mix Asphalt pavements
    (University of Dar es Salaam, 2006) Adams, Frank
    Hot Mix Asphalt (HMA) is used for road construction in order to provide a waterproof road surface and a pavement that is able to resist loads imposed by traffic. HMA is also used for road maintenance and rehabilitation. Hot Mix Asphalt Pavement (HMA) however, is subjected to wear and tear caused by factors such as weakness of materials, environment and the traffic which ultimately reduce the pavement life. Either where maintenance and rehabilitation measures have been applied, the cost of such measures are high. The addition of hydrated lime in the HMA has been reported to improve its properties. This study is concerned with the investigation on how hydrated lime improves resistance against stripping (moisture damage), resistance to permanent deformation (rutting) when varying percentages of hydrated lime are added. The results obtained indicate that the addition of 2% hydrated lime increases the mix stability by 12%, the mix flow by 52%, and the index of retained strength, an indicator of resistance to stripping by 17.1%. The results also shows that Lime minimizes strains for about 10%.The results of economic analysis indicate also that the use of hydrated lime in HMA is cost effective. The maximum savings obtained in Net Present Value (NPV) of costs is 36%. From the results obtained, it can be concluded that addition of hydrated lime in HMA improves its mix properties. It gives additional resistance to deformation and the resistance against stripping. Addition of lime is also cost effective and therefore there are life cycle benefits of adding lime in HMA mixes as compared to mixes without lime. It can be concluded from the LCCA results that lime adds life to the period that the pavement normally performs.