WASTE MATERIALS, BY-PRODUCTS, AND RECYCLED PRODUCTS

The report examines current innovative practices and research needs concerning the use of wastes and by-products that result from industry, mineral processing and domestic sources, and considers the recycling of road-building materials. Of the 3.5 billion tons of solid wastes generated annually, the largest tonnage is accounted for by fly ash, blast furnace slag, steel slag, foundry wastes, coal refuse, dredge spil, phosphate slime, and tailings of copper, taconite, and iron ore. In addition to their use as aggregate and filler, many by-products can be used as binders. The probable uses of 53 waste materials is tabulated. Two types of pavement recycling were discussed: in-place recycling and recycling through a central plant. Recent, ongoing and proposed research projects are tabulated and areas requiring research are noted.