Sulfur aggregate interaction

Rheology of SA Binders. Conventional test methods such as softening point, viscosity, penetration, Fraas break point, ductilities, etc. have been used to characterize the rheology of SA binders (11). The physical structure of SA binders is complex, and the sulfur-asphalt and sulfur-aggregate interaction make correlations to asphalt and to binder properties for aggregate rather difficult. 

Sulfui>-Aggregate Interaction. Substantial increases in stiffness of SA binder-based mixes, as measured by the Marshall test, tensile strength, and resilient modulus of elasticity, have been observed with increasing sulfur-asphalt ratio of the binder used (11, 15, 16). Such increases can, of course, be attributed in part to the increase in viscosity of the SA... 

Detailed photochemical studies of RBS and RRS have revealed that the photolysis of RRS produces RBS and NO quantitatively (Scheme 5.6) and the RBS produced undergoes further photodecomposition to generate NO and iron (III) [165, 168]. RBS has been tested as an NO delivery drug to the vascular and brain tissues by thermal as well as photochemical means [169, 170]. Due to the high solubilities in aprotic solvents, Roussin s salts are able to penetrate the endothelial cell membrane easily and deliver NO for hours [169]. RBS has been found to inhibit ADP-induced platelet aggregation [171] and Roussin s salts in general show a bacteriostatic effect, presumably due to the interaction of released NO and iron-sulfur proteins [172]. 

FIG. 3 Colloidal aggregate formed in the air-water interface. The aggregated particles are polystyrene spheres of diameter 2.26 /un. In the air-water interface the particles develop an electric-dipole perpendicular to the surface, which prevents them from aggregating. Aggregation is induced by adding to the water solution a small amount of electrolyte which screen the dipolar interaction. In the sample shown here, sulfuric acid was added to the water until a pH of 2 was reached. Courtesy of Prof. Jaime Ruiz-Garcia, Instituto de Fisica, Universidad Autonoma de San Luis Potosi. 

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