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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-11-9443, The skid resistance of typical pavement marking materials is determined. A data base of full-scale locked-wheel skid resistance is presented for typical traffic paints of various formulations, hot spray and extruded thermoplastics, cold preformed plastics, temporary tapes, and some two-part systems. A variety of pavement surface types including dense and open graded asphalt and portland cement concrete are used in the study. In Volume I texture data are presented for field applications and for laboratory samples. Equations are developed for predicting skid resistance from texture measurements. The effects of glass beads, weathering, and polishing are examined in laboratory and field experiments. Based on a simulation, guidelines are developed for the maximum acceptable differential skid resistance between a pavement and the marking materials on it. Both two-and four-wheel vehicles are treated. Volume II of this report contains a complete listing of the data compiled in this project and is available in limited quantities to interested researchers. A summary of all the data which was utilized in the formation of the conclusions are included in tables of Volume I.

DOT-FH-11-9131, The abundance of cellulosic-based wastes was reviewed by section of the country and type which includes: wood wastes, municipal wastes and manures. Of the most promising waste conversion processes now under consideration, pyrolysis, liquefaction, and hydrolysis were selected for preliminary laboratory screening. Model wastes for this study included several pyrolysis oils, paper, sawdust and dried cow manure. Distillate oils produced during wood waste pyrolysis (WPO) served best as precursors of products that approximated bitumens and highly viscous fluids. In the statistically designed study of process parameters which followed, the best conditions were identified for distilling and hydrogenating the crude WPO for conversion to a usable product (hydrogenate). This hydrogenate, because of its high oxygen content, could be added to conventional asphalt only in amounts up to ca. 15 weight percent concentration with little or no observed property change. In combination with sulfur, the ternary system-AC/hydrogenate/S:29/29/42 had a penetration value comparable to that of AC/S:65/35. A 909 metric ton/day waste processing facility could be cost effective in producing 72.7 metric tons per day of pyrolysis product equivalent to 318 metric tons or more of blended binder. This assumes that waste is available at no cost and that coproduct oil and char are credited at equivalent heating values.

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.