Abstract:
The problems associated with the environmentally safe and efficient disposal of waste continue to grow. In many areas, existing landfills are beginning to fill up, and a “not-in-my-backyard” philosophy has made the establishment of new landfills very difficult. The cost of disposal continues to increase while the types of wastes accepted at municipal solid waste landfills are becoming more and more restricted. One answer to all of these problems lies in the ability of society to develop beneficial uses for these waste products. Pakistan is a developing country and in order to open new avenues of prosperity there is a need to develop roads network throughout the country. The use of waste byproducts in lieu of virgin materials would relieve some of the burden on the ailing economy of the Pakistan.
This study is not only aimed at using two waste products i.e fly ash and granulated blast furnace slag as road construction materials but also to see how these can improve the properties of asphalt mix design at high temperatures.
Effect of partial replacement of the fine aggregate and mineral filler at 30%, 40% and 50% replacement levels with fly ash and blast furnace slag was studied at 60oC, 65oC, and 70oC temperatures. Asphalt content was varied from 4% to 5%. Tests were carried out according to ASTM and AASHTO specifications. Marshall properties of the various mixes were evaluated. The best results satisfying all the specification requirement according to NHA specification A were obtained at 50% replacement level with fly ash alongwith blast furnace slag at 5% bitumen content at 65oC. Thus the use of blast furnace slag alongwith fly ash is useful in areas experiencing high temperatures during summer.
