| High carbon fly ash and most post consumer plastics are considered by industry to be waste materials that have limited or no use in the raw form in which they exist. This research was initiated to develop a lab scale process that compounds these two materials via twin-screw extrusion to manufacture a synthetic lightweight aggregate (SLA). Through a variety of ASTM methods, the material's physical properties are evaluated. Aggregate was produced in a number of lab and pilot scale studies. The aggregate was used in several applications including concrete, CMUs for light construction and hot mix asphalt (HMA) used to reduce the rutting potential in roads and highways. The lab scale process was scaled up to a pilot scale process and it was shown that mixing efficiency was increased dramatically. To make the aggregate even lighter, the material was foamed using a process to produce a closed cell, lower density aggregate. Although the material was lighter by volume, the strength to weight ratio was reduced and applications differ due to the reduced strength of the material. Through an economic analysis, it can be shown that the manufacture and sale of SLA can potentially be a profitable venture. |
