Investigation of properties of stone mastic asphalt modified with waste polyethylene terephthalate.
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Stone Mastic Asphalt is a gap graded type of Hot Mix Asphalt that’s is used on high volume traffic roads.The bituminous mix is designed to have a high coarse aggregate content and high binder content.However, one of its major drawbacks is its high binder drain down, attributed to its gap graded nature. Research has indicated that addition of polymers into bituminous mixes improve the adhesive and cohesive bond between aggregates and binder. This helps enhance the properties of the mixes thus improving pavement performance. One of the cheapest and most readily available polymers are plastics. Use of waste plastics as stabilizers in asphalt mixes not only improves their properties but also helps promote proper solid waste management.The emphasis of this research therefore is to investigate the effect of addition of this PET on certain properties of SMA. The materials used were granite aggregates and bitumen grades of 60/70 and 80/100. The optimum bitumen content for unmodified mix was determined and this was used as the control. From this, the optimum PET content was determined for the separate bitumen grades as 10% and 8% for bitumen grades of 60/70 and 80/100 respectively. The modified SMA had improved Marshall stability, flow, and volumetric properties compared to the conventional SMA.Also the resistance to moisture damage was determined using the moisture susceptibility tests. Modified SMA had a higher resistance to moisture damage compared to the unmodified SMA.