Aggregates, which constitute 95 percent of all construction materials, have always been and will continue to be an important factor in the longevity and performance of transportation structures. With restricted transportation budgets, more emphasis is being given to longevity, so quality of aggregate is important. Improved aggregate tests that enable better evaluation of aggregate quality adn consideration of waste or by-product materials as substitutes for natural aggregate are needed to build durable structures, as well as to protect the environment and conserve natural resources. This volume contains eight papers arranged into two groups. In the first group, information from research related to waste and recycled materials is provided. These studies resulted in data on the use of shredded rubber tires as lightweight material for construction of roadway embankments, use of crushed glass as a partial replacement for natural aggregate, use of slag aggregate from phosphogymsum in portland cement concrete, and use of waste foundry sand as partial replacement of aggregate in asphalt concrete. In the second group of papers, the development and use of aggregate tests based on new technologies are described. Information presented includes an automated method of determining fine aggregate gradations, a slightly modified National Aggregate Association flow test method for determining fine aggregate angularity, an image analyzer for automatic determination of the percentage of natural sand in an aggregate mixture, and a stoichiometric analysis for identifying the original mineral compositions of aggregate used in portland cement concrete.
Samenvatting