Abstract:
Steel production industry produces hundreds million tons of steel slag every year according to World Steel Association research. This by-product poses numerous environmental hazards as a result of landfill disposal solution, particularly concern about leaching. In civil construction projects the use of steel slag aggregate has been more popular in recent years such as in asphalt pavement, concrete masonry, embankment, and railroad ballast. Such kind of nonrenewable resources have been depleted in a significant amount by roads development. Hence, using the steel slag as a substitute for traditional aggregate in hot mix asphalt (HMA) is a viable way to relieve environmental pressure and conserve natural resources. Similarly, mineral filler Fly ash is one of the byproducts of coal burning plants, consisting of tiny particles mixed with flue gases. Being a waste material, it is usually dumped on the ground. Therefore public road industry is capable of utilizing such waste material in high margin. Fly ash has been effectively used as a filler in bitumen mixes for a long time as it has the benefits of enhancing bitumen mix resistance. This research aims to analyze the usability of fly ash (FA) as filler and Steel slag as coarse aggregate , which are the environmental pollutants, in asphalt concrete in order to monitor its microwave heating rate to promote self-healing. Using Marshall, Hot mix asphalt (HMA) mixtures were developed for control and three different modified specimens having 10%, 20% and 30% Steel slag coarse aggregates and optimum fly ash content (OFC) as filler. Then the thermal distribution as well as the optimum healing time of test specimens were recorded using thermal infrared gun. The three-point bending tests were applied to specimens before and after each microwave healing procedures. Test results demonstrated that adding steel slag and fly ash in asphalt concrete mixtures increases the heating rates of asphalt concrete and improve the healing performance of HMA using microwave heat. The replacement of regular Coarse aggregate by 30% steel aggregate is extremely promising since it has not only improved healing results but also helps the entire mixture enhance the load-displacement relationship with more ductile behavior. Overall, the use of steel slag and fly ash in HMA is a significant option that helps to the sustainable development of asphalt concrete since it improves self-healing and mechanical properties
