Browsing by Author "Teklu, Webeshet"

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    Effect of Gradation of aggregates on the rutting performance of hot mix asphalt
    (Addis Ababa University, 2015-12) Teklu, Webeshet; G/Egziabher, Efrem (Eng)
    High proportion of asphalt mixes is made of mineral aggregates. Therefore, most of the performance problems are directly or indirectly related to the physical and chemical properties of aggregates. Various studies have shown that the variation in gradation of aggregate have significant effect on the performance of asphalt concrete pavements. This study was intended to investigate the effect of gradation of aggregate (sourced from basalt) in the rutting performance of hot-mix-asphalt. Using different percentage of the mineral aggregates to be retained on different standard sieve sizes, a number of trial mixes have been prepared using Asphalt Institute and Bailey method of Gradation specification by the standard Marshal Mix design procedure to arrive at asphalt concrete mixtures that fulfill the Marshal criteria. The effects of each gradation type on Marshal Properties of the asphalt mixtures at their respective optimum asphalt content were evaluated and possible causes for such difference in properties and relationships in between the studied properties was discussed. Performance tests chosen to measure the permanent deformation of asphalt mixes is wheel tracking tests and Relationship between rutting and factors affecting rutting were studied. Relationships have been developed to predict the impact of Hot Mix Asphalt properties on its permanent deformation behavior. Changing percentage passing values of different sieves to tolerances value has shown significant change in the rutting performances of HMA. In addition to this, it has been revealed that mixes with coarser gradation showed better resistance against rutting. When compared to conventional mix by AI gradation, Bailey method of gradation has given good result in rutting performance. Moreover, the CA ratio used in Bailey method has a good R² value to forecast the rutting performance.