Asphalt Questions With 100% Correct Answers.

Asphalt Chemistry - Bituminous material are *hydrocarbons* -very complex chemical composition that depends on the oil source and refining method -*Molecular structure is more important than composition* Asphalt types used in pavements - *Asphalt cement (asphalt binder)* -used for HMA(hot mixed asphalt) *Asphalt emulsion* -used for cold mix and maintenance applications *Asphalt cutback* -used for cold mix and maintenance applications. Asphalt Cement (binder) - Adheres to most rock -waterproof -fairly durable -*resistant to reaction with most acids, alkalis, and salts.* -*temperature sensitive* Asphalt Emulsion - = asphalt cement + water + emulsifying agent (typically soap) -same uses as cutback-safer and environmentally better BUT its can be more expensive. Asphalt Cutback - =asphalt cement + solvent Hazardous, volatile solvents and hydrocarbons are released. Cold mix maintenance, patching, chip seals, crack sealing, base and sub-base stabilization, and surfacing low volume roads. Asphalt in paving - asphalt binder alone is also used for sealing and waterproofing -Asphalt concrete = asphalt binder + aggregate (used mainly for hot mix asphalt pavement surfacing. Visco-Elastic - Asphalt binder is a visco-elastic material -viscous at high temps like a fluid -elastic at low temps, like a solid *its characteristics depend on both temperature and loading rate* -complex chemical properties -asphalt binder's specifications are based on physical properties Is asphalt susceptible to temperature change???? - *YES* asphalt is highly affected by temperature -slope indicates the degree of susceptibility -some additives can reduce susceptibility due to temperature.What grades does asphalt come in? - -*Soft (low viscosity) asphalt* is used in cold climates to avoid thermal cracking. -*Hard (high viscosity) asphalt* is used in hot climates to avoid rutting. Simulation of aging in the lab - *Rolling thin-film oven* -short-term aging to simulate hardening during construction *Pressure Aging vessel* -Long-term aging to simulate hardening in service. - aged in the RTFO first, then 20 hrs at 305 psi What are some types of Performance Grade Binder Tests - -Flash Point -Viscosity (rotational) -Dynamic shear rheometer( neat, Rutting, Fatigue) -Bending beam rheometer -Direct tension