1985 August

MSU Clip Sheet newsletters published in August of 1985

Planck sorption cooler system user manual

Keywords: space cryogenics, space operations, space instrumentation, thermal control, CMB cosmolog

Investigation of Asphalt Additives

DTFH-61-84-C-00066The overall objectives of this research were to (l ) identify through laboratory testing, the most promising types of additives or admixtures for reducing rutting and cracking in hot-mixed asphalt pavements, (2) develop guidelines showing how the additives can be incorporated into actual pavements and (3) develop procedures for evaluating additives. Additives selected for evaluation included latex, block copolymer rubber, ethylene vinyl acetate, polyethylene and carbon black. The additives were combined with asphalt cements from two sources with widely differing chemical composition and rheological properties. Asphalts two grades softer than that normally used in hot-mixed asphalt concrete were used with the additives. Binder tests included penetration at two temperatures, viscosity at various temperatures and by various methods, softening point, flash point, specific gravity, rolling thin film oven test, ductility, heat stability, infrared analysis before and after artificial aging, nuclear magnetic resonance, viscoelastic analysis, stress relaxation, and Rostler-Sternberg and Corbett analyses. Energies of interaction between selected asphalts and additives were measured using a microcalorimeter. Paving mixture tests included Hveem and Marshall stabilities, resilient modulus vs. temperature, indirect tension vs. temperature and loading rate, resistance to moisture damage, flexural fatigue, creep/permanent deformation, fracture resistance and fracture healing. The mixture test results were used with the VESYS IV structural subsystem to predict the effects of the additives on pavement- performance, cracking, rutting, and roughness. All additives demonstrated the ability to substantially alter the temperature susceptibility of asphalt concrete mixtures