The impact of using rubber on asphalt mix design

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Ibraheim Faisal Soliemea
Raghad Faleh Al-Zerie
Rinal Anwar Abduall
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As the number of vehicles is growing rapidly, the amount of waste tires is also increasing. Used tire disposal and recovery is a great challenge. Unlike most types of solid wastes, used tires cannot be landfilled whole. Discarded tires present a variety of hazards for the environment and public health, including air and water pollution, disease-carrying vectors, and potential fires at both illegal dumps and regulated tire stockpiles. So, it’s a good idea to use this waste stuff in something beneficial. The purpose of this study is to investigate the impact of using car tires in asphalt mixture. This study reviewed the use of crumb rubber (shredding tires) in bitumen using the wet process and focused on the crumb rubber as a replacement to the total weight of bitumen. From the material point of view, the tire is made up of three main components: elastomeric compound, fabric and steel. The process involves tire shredding and chipping into strips which is carried out by using machinery that cuts up the tiers into small pieces of different sizes. After the removal of the steel and fabric components, the material can be used with asphalt mixture. Strips then are ground into bits of the size of sand grain, called crumb rubber. Then the crumb rubber mixed with traditional asphalt (aggregate, bitumen). A comparative study has been done between the unmodified and modified asphalt mixtures considering the Marshall Stability value, the volumetric properties and other properties. The tests were performed using bitumen (80/120) and rubber taken from used tires under the age of (10) years, knowing that, we used three different aggregate grading of diameters, granulated rubber crumbs and different ratios grains (5, 10, 15, 20) % of bitumen. The results were expected to be positive. With the increase of the rubber proportion, ductility decreased and softening point rose. Rubber modified asphalt mixtures increased in stability and decreased in the flow rate compared with other mixtures. The results were compatible with one of the similar studies conducted in the KSA. It was observed from the experimental work and calculations that the results were satisfactory. The properties of rubberized asphalt met the specifications. Consequently, the mixture can be successfully used in paving roads and can provide an environmentally friendly solution for the waste problem of tires.