Asphalt Binders Exam 2 Questions with 100% Verified solutions| Graded A+

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What is asphalt? - ✔✔generally a by-product of petroleum distillation; a complex hydrocarbon; soluble in petroleum products; can be naturally-occuring What is tar? - ✔✔generally a by-product ... of coal production; resistant to petroleum products How can a source of asphalt be identified? - ✔✔by solubility tests Where was asphalt obtained from originally? - ✔✔Island of Trinidad and Venezuela; lakes What are petroleum-based asphalts? - ✔✔a waste product from refinery-processing of crude oil; "bottom of the barrel"; properties depend on refinery operations and composition depends on crude source What are the three bituminous material types? - ✔✔1. asphalt cement/hot mix asphalt 2. emulsified asphalt 3. cutback asphalt What are emulsified asphalts composed of? - ✔✔asphalt cement, water, and an emulsifying agent What are cutback asphalts composed of? - ✔✔asphalt cement with petroleum solventWhat are the basic steps of refinery operation? - ✔✔1. pumping 2. storage 3. heating 4. distillation 5. condensing and cooling 6. separation What are the three components of asphalt? - ✔✔asphaltenes, resins, and oils What do emulsifiers do? - ✔✔give surface charge to asphalt droplets suspended in water medium; anionic (limestone compatible) or cationic (siliceous gravel compatible); allow for bitumen to be mixed at lower temperatures; cheaper, safer, and better for the environment compared to cutbacks. What are three cutbacks? - ✔✔1. Rapid Cure (RC); high volatility of solvent; tack coats and surface treatments 2. Medium Cure (MC); moderate volatility; stockpile patching mix 3. Slow Cure (SC); low volatility; prime coat and dust control good for fast projects, but not used because it's harmful for the environment What were the early specification for lake asphalts and for petroleum asphalts? - ✔✔lake asphalts: -appearance -solubility in carbon disulfide petroleum asphalts: -consistencyWhat is consistency? - ✔✔the way a liquid holds together; stiffness; softness or hardness What specifications for petroleum asphalts developed? - ✔✔1. penetration grade (scale of hardest to softest) 2. viscosity-graded specifications (scale of softest to hardest) 3. superpave binder specification What is viscosity? - ✔✔the ratio between the applied shear stress and the rate of shear strain Why is viscosity an important test to perform on asphalt? - ✔✔a relationship between temperature and viscosity can be determined, and there exist ranges of compaction and mixing What does superpave stand for? - ✔✔superior performing pavement What is asphalt binder selection dependent on in superpave specifications? - ✔✔performance (rutting, fatigue cracking, low temperature cracking) What is the basic superpave specification? - ✔✔performance grade (PG), which is based on physical properties What affects the superpave specification? How does it affect it? - ✔✔climate; the first number is the average 7-day maximum pavement temperature, and the second number is the minimum pavement temperatureWhat criteria must be considered when selecting an asphalt binder? - ✔✔1. geographic area 2. air temperature 3. pavement temperature 4. loading type 5. reliability What were superpave specifications developed from? - ✔✔air temperatures How does testing for performance grade work? - ✔✔test the same type of asphalt for multiple temperatures until the sample fails to meet the specification requirement; the asphalt belongs to the grade based on the last temperature that passed the specification What are the four performance grade binder tests? What do they help simulate? - ✔✔1. Rotational Viscometer (RV); temperature-viscosity relationship 2. Direct Shear Rheometer (DSR); rutting & fatigue cracking 3. Bending Beam Rheometer (BBR); low-temperature cracking 4. Direct Tension Tester (DTT); low-temperature cracking What is aging as it relates to asphalt? - ✔✔asphalt is a petroleum product and oxidizes and hardens over time What are two binder aging methods? - ✔✔1. Rolling Thin Film Oven (RTFO); simulates manufacture and construction aging2. Pressure Aging Vessel (PAV); simulates long-term pavement aging What is RAP? - ✔✔reclaimed asphalt pavement (RAP) is recycled asphalt pavement; superpave transition was difficult due to grading difficulties and mixing difficulties, but partial blending occurs to a significant extent; may have to adjust the performance grade. see https://engineering.purdue.edu/NCSC/library/video.htm [Show More]

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