Methodology for determining most suitable compaction temperatures for hot mix asphalt

Using an in-correct compaction temperature of hot-mix asphalt has caused significant problems not only in practice but also in the determination of optimum asphalt content in the design of mix. Asphalt mixture usually looses their temperature during transportation and when laying down. The main objective of this research is to determine the most suitable value of compaction temperature of asphalt pavement that would be use in both laboratory investigations and in field technique Laboratory measurements has been done to find out the effect of various compaction temperatures on the values of the optimum bitumen content and the volumetric properties and Marshal properties of asphalt mixtures. Field measurements were also done to determine the effect of different temperatures of asphalt pavement during laying-down and compaction process on the relative compaction of asphalt mixtures and on the pavement macriotexture. In addition the rate of heat loss of asphalt mixture during transporting it from mixing plant to was determined in both summer and winter seasons. The main conclusion of this investigation is that pavement compaction temperature has a significant effect on the optimum bitumen content (OBC) of asphalt mixtures. Also it has remarkable effect on the values of volumetric properties of hot mix asphalt and Marshall indicators. Field investigations reveal that the Relative Compaction (RC) of the asphalt pavement layer is significantly affected by the temperature of asphalt mixture during compaction and is acceptable up to 110oC. Also, asphalt pavement macrotexture is deeply affected by the value of compacted temperature. A model was developed to relate compaction temperature to the depth of surface texture of asphalt pavement surface. The field results confirmed to a large extent the Laboratory results.