Engineering and Technology Journal

The recycling asphalt paving creates a cycle for the use of materials that improve the use of natural resources, as it reduces the use of new materials from the aggregate and asphalt, which can be a rare commodity in some areas. The increasing in the use of milling machines nowadays led to the production of large amount of wasted materials, recycling is consider an important solution that can take them into consideration when creating a network of new roads or rehabilitation of damaged networks. This process has many advantages. It is reduce the environmental pollution and preserves natural resources as well as economic benefit. The main objective of this study is to evaluate recycling material through Marshall test and knowing their validity and can be used in hot mix asphalt in the construction and maintenance of road networks in Iraq, with finding the best ratio of mixing with the new material. Where it was planned to use old materials from one of the streets of Mosul city, while the new material consisting of asphalt Grade (50-60) are included within the aggregate of binder course and cement as a filler. Optimum value of the asphalt content was found by Marshall method through the preparation of a mixture of new material and use this value in the preparation of mixtures of recycled where it was the use of five percentages of recycled materials, namely, (0%, 20%, 30%, 50% and 100%). These mixtures were exposed to : the Marshall test to find their characteristics. The results show that recycling rates up to 50% of recycled materials were perform well within specification limits for use, while 30% was considered as the ideal ratio showed better performance in all characterstics. Showed 30% increase in Marshall stability of the mix for the base mix to more than 41% and other characteristics are within the specification limits.

The proportions of aggregate directly affect the performance of HMA depending on their shape, texture, and strongly on the gradation.The determination of aggregate proportions depends strongly on the number of aggregate typesto be blended, and the limits of the desired gradation.
In this research, ten samples had been taken from different text books and papers. Each one contains three types of aggregates; coarse, fine, and filler. The samples were solved individually by seven different methods; five of them by graphical method, the sixth method was solved by running MATLAB, and the last method by using Excel sheet. In this research, five graphical methods were applied, and the aim of using them is to find graphically the tentative blending values and then compare their results individually with optimum values which was found from an Excel spreadsheet, and finally selecting the optimum method. For this purpose, more than 210 readings were utilized.
SPSS program was run two times. In the first run, the values of person correlation (r) of method,Balanced-Areas (Rothfuchs), Walace, Equal Distance, Triangular, and Asphalt Institute when correlated with optimum values were 0.973, 0.964, 0.958, 0.953, and 0.869, respectively. In the second SPSS run, the values of samples No.4 and No.10 were removed because they gave zeros readings, the person correlation of Triangular, Balanced-Area, Walace, Equal Distance, and Asphalt Institute methods were 0.972, 0.970, 0.959, 0.952, and 0.869, respectively.
In this research, It has been found that the Equal Distances method would be considered as an accurate, fast, and even easy method, and can be used for any number of aggregate.