Potential of glass cullet as aggregate in hot mix asphalt
The increasing quantity of non-biodegradable waste has posed major environmental concern especially in the developing countries. To improve such challenge, the effects of crushed waste glass bottles (cullet) as partial replacement of fine aggregate in the properties of Hot Mix Asphalt (HMA) was investigated. The waste glass was crushed and sieved through series of sieves to determine its gradation. The optimum bitumen content (OBC) was determined using Marshall Mix Design Method. A total of 33 cylindrical specimen of asphalt produced with sand and sand partially replaced with glass cullet were prepared. 15 specimen were used to determine the OBC using of 5.0, 5.5, 6.0, 6.5 and 7.0 % bitumen to the total blended aggregate weight. The remaining samples were used to investigate the effects of glass cullet on the bituminous mixture at the selected OBC using Marshall Test. The results of the laboratory tests indicate OBC of 5.9%. Stability, flow, specific gravity and air voids were determined from the Marshall test and were compared with those specified by The Asphalt Institute and the Nigerian codes for Roads and Bridges. Optimum glass cullet content of 8.0 % was obtained. Asphalt produced with 8 % glass cullet can be used as wearing course material. Use of glass cullet will provide an effective way of disposing the waste.
Keywords: Glass cullet, Glasphalt, Hot mix asphalt, Optimum bitumen content, wearing course, Marshall test, Aggregate