Study the Effect of Crushed Waste Iron Powder as Coarse Sand and Filler in the Asphalt Binder Course

Abstract

Various solid wastes that are emerged from steel plants are blast furnace slag, blast furnace flue dust, sludge and mill particle. Therefore, use of waste materials in road pavements is nowadays considered not only as a positive option in terms of sustainability, but also as an effective option in means of providing enhanced performance in service. This is especially true in the case of reuse of waste iron. In this research, a number of aggregate tests are conducted which are: sieve analysis, specific gravity, absorption, abrasion, adsorption and scanning electron microscope. These tests are to investigate the applicability of using the waste iron powder (WIP) as an asphalt binder in road pavements. Moreover, as a comparison, the same tests were applied on the conventional aggregates. Furthermore, number of bitumen tests is conducted. They are penetration test, softening point, ductility, flash point and specific gravity. Marshal samples are prepared using both conventional blending aggregates and (WIP) to investigate the properties of the asphalt mix: stability, flow, bulk density and comparing the results with the specifications. WIP were introduced in the asphalt mixture in grinded form 0 – 2.00 mm. Marshal mix design procedure was used, first to determine the Optimum Bitumen Content (OBC) and then further to test the modified mixture properties. In total, (58) samples were prepared, 30 samples were used to determine the OBC for two stages and the remaining were used to investigate the effects adding different WIP percentages to asphalt mix. At the first stage, the OBC was 5 % by weight of asphalt mix. Moreover, at the first stage, the ratio of sand was 5% from weight of aggregate, Four proportions of WIP by weight of aggregates were tested 1.25, 2.5, 3.75, and 5%. Besides, testing of ordinary asphalt mix. The results showed that it is possible to use the WIP in preparing the asphalt binder course. WIP content of 5 % by weight of aggregate for asphalt mix is recommended as the optimum WIP content for the improvement of performance of asphalt mix. Asphalt mix modified with this percentage has approximately 23% higher stability value compared to the conventional asphalt mix. The second stage is done to ensure the results that appeared at first stage by increase the ratio of WIP 7.5 and 10%. Asphalt mix modified with higher percentages of WIP shows higher bulk density, higher flow and higher air voids.