FHWA Demonstration Project 59

793005174Final report.PDFTech Report84-DP59-MS-05Waste productsFly ashAggregatesPavementsMississippiMississippi. Dept. of TransportationBarstis, William F.Crawley, Alfred B.Mississippi. Dept. of Transportation. Research DivisionUnited States. Federal Highway AdministrationNTL-HIGHWAY/ROAD TRANSPORTATION-MaterialsUS Transportation CollectionMuch attention has been focused in recent years on conserving natural resources and energy. Numerous waste products and/or byproducts from various industrial and commercial processes, normally deposited in landfills, have been proposed for use as alternate construction materials. One byproduct that has shown considerable promise as an alternate construction material is fly ash when used in a lime-fly ash (LFA) base course. This paper describes the use of this waste product in LFA stabilized granular materials as an alternative to cement treated materials for base construction. The primary disadvantage of a cement treated base (CTB) is the environmental (shrinkage) cracking that leads to the infiltration of rain water and incompressibles, pumping of subgrade soils, spalling of the crack faces and other problems that adversely effect pavement performance. It has been shown that the slow strength gain associated with LFA leads to a condition where the microcracks in the material are generally healed before they can develop into macrocracks. Continued chemical reactions, known as autogenous healing, within the mix are largely responsible for this behavior