Stress relaxation and mechanical properties of RL-1973 and PD-200-16 silicone resin sponge materials

Stress relaxation tests were conducted by loading specimens in double-lap shear to a preselected strain level and monitoring the decay of stress with time. The stress relaxation response characteristics were measured over a temperature range of 100 to 300 K and four strain levels. It is concluded that only a slight amount of stress relaxation was observed, and the stiffness increased approximately two orders of magnitude over the range of temperatures

Laboratory Development of Third/Fourth Generation Sulphlex Binders

Study No. 7208This report presents the findings of a 2-year, multitask study to provide a new generation of Sulphlex binders with enhanced low-temperature fracture resistance. The initial phases of the program dealt with the preparation and base-line characterization of Sulphlex 233 and 198, First and Second Generation Sulphlex, respectively, considered the more promising of a broad series of formulations developed under earlier Federal Highway Administration programs. These binders were prepared individually and blended at ratios of 50/50 and 75/25 (198/233) and designated as Third Generation Sulphlex. The former was prepared by directly blending the two binders as well as by a one-pot synthesis. These binders were subjected to a series of screening tests including (a) Penetration @ 25 deg C, (b) Viscosity @ 135 deg C, (c) Specific Gravity, (d) Solubility in CHCl3, (e) Storage Stability, and (f) Glass Transition temperature. A "new and improved" Sulphlex binder designated as Fourth Generation was formulated utilizing the rationale derived from the earlier systems. Sulphlex mixtures along with a control using an AC-20 asphalt were prepared using a crushed limestone aggregate and tested in accordance with Asphalt Aggregate Mixture Analysis System (AAMAS), American Association of State Highway and Transportation Officials (AASHTO), Strategic Highway Research Program (SHRP or Superpave), and Viscoelastic Systems (VESYS) procedures including (a) Indirect Tension, (b) Diametral Resilient Modulus, (c) IDT Creep, (d) Compressive Creep, (e) Unconfined Compression, (f) Repeated Load Permanent Deformation, and (g) Aging using Resilient Modulus. A set of generic manufacturing plans and procedures were generated for the production of Sulphlex in sufficient quantity to satisfy the requirements of an hypothetical test road section

Environmental and Safety Aspects of the Use of Sulfur in Highway Pavements - Volume I - Evaluation of Environmental and Safety Hazards

DOT-FH-11-9457The use of sulfur in highway paving mixtures has introduced questions regarding the pollutants generated, their environmental impact and the safety aspects associated with mix preparation and placement. This report presents the results of an investigation in which these factors are assessed. The study considered the safety and environmental aspects of storage and handling, formulation, construction, operation and maintenance of highway pavements containing sulfur. These considerations included possible evolution of toxic and obnoxious fumes, dust and runoffs. Results of tests simulating in-service conditions such as traffic wear, skidding, freeze thaw, spills and fires are also discussed. The effects of these pollutants on humans, soils, highway structural materials, ground waters and vegetation is presented. Along with the laboratory study a detailed work plan which discusses methods and equipment for monitoring potential emissions and pollutants and recommended safety practices was generated. An annotated bibliography dealing with the safety and environmental effects on sulfur-modified paving materials was also prepared. The final report was prepared in three volumes: Volume I - Evaluation of Environmental and Safety Hazards; Volume II - Field Evaluation Plan and Volume III - Annotated Bibliography

Extension and Replacement of Asphalt Cement with Sulfur - Executive Summary

DOT-FH-11-8799The 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