Search

FH-11-8784, This study was performed to determine the availability of mining and metallurgical wastes in the United States and to assess their potential for use in various aspects of highway construction. A comprehensive literature survey was performed to develop information on locations, amounts, compositions, and uses of various mining and metallurgical wastes. Knowledgeable personnel in the mining industry, governmental agencies, trade associations, and universities were contacted to obtain additional unpublished information. The information was used to inventory, classify, and evaluate these wastes. Over 1.6 billion tons of mining and metallurgical wastes are generated each year. Although a small percentage of all this material is actually being used, a number of mining and metallurgical wastes have been successfully utilized as highway construction material. A number of other mineral wastes are potentially useful with some degrees of processing. Materials most highly recommended for use in highway construction are gold gravels, steel slag, lead-zinc chat, phosphate slag, taconite tailings, copper slag, and waste rock from the mining of copper, fluorspar, gold, and iron ore.

DOT-FH-11-8027, The use of incinerator residue as an aggregate in a bituminous base (termed littercrete) was studied. Test sections consisting of the experimental hot mixed littercrete base and a conventional hot mixed asphaltic concrete base (termed blackbase control) and topped with a conventional surface were placed on a city street in Houston, Texas. This report presents the results from observations and tests on cores during the first three years of in service performance. Results of the laboratory and field evaluations show that the littercrete section is performing in an excellent manner, almost identical with the conventional blackbase control section. The only distress that has occurred is minor cracking in both sections. This cracking is limited to the conventional wearing surface and has not progressed into the bases.

DOT-FH-11-8799, The potential shortage of asphalt cement and oversupply of sulfur make it advantageous to reduce to dependence of the paving industry upon asphalt cement while utilizing readily available sulfur. This report presents the results of an investigation of the use of elemental sulfur as a partial replacement and/or extender of asphalt cement in highway paving mixtures. Physical properties of numerous combinations of sulfur-asphalt emulsions were determined. Various aggregates, asphalt cements, and sulfur were tested in a series of laboratory screening tests utilizing nine independent design variables. Characterization tests were performed on selected combinations of aggregate, asphalt and sulfur utilizing three different mixing methods. The resulting relationships between response characteristics, mixture compositions, and design variables were programmed into the Texas FPS-BISTRO and VESYS IIM design programs. Texas FPS-BISTRO screened a number of design combinations to find the optimum combinations. VESYS IIM was used to evaluate performance of selected optimum pavements. The studies indicate that the addition of sulfur to asphaltic concrete can produce pavements which are more economical with performance characteristics equal or superior to conventional asphaltic concrete pavements.

DOT-FH-11-9111, Asphalt and Portland cement are the principal binders used in the preparation of pavements. The costs of these materials are directly related to energy and are expected to increase. The availability of asphalt in the future in the event of an oil embargo or other crisis is questionable. Native as well as by-product sources of sulfur in the United States are large and are expected to increase in the future. Sulfur in its elemental form is not ideally suited for use as a pavement binder because of its brittle and friable nature. This program was under-taken to determine if elemental sulfur could be inexpensively modified so it could be used as a pavement binder. As a result of this work, a new pavement binder system, based on elemental sulfur, has been developed that can serve as a replacement for asphalt and Portland cement. This material can be emulsified with water and used like asphalt emulsions.