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26 Cards in this Set
- Front
- Back
Define viscosity |
the ratio between the applied shear stress & the rate of shear |
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What are 4 desired properties of aggregates used in asphalt? |
toughness, soundness, deleterious materials, gradation |
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What are the 3 gradations and what are each of their properties? |
Uniformly Graded: poor interlock, high perm. Well Graded: good interlock, low perm. Gap Graded: good interlock, low perm. |
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What is the "Nominal Maximum" and what is "Maximum" when referring to aggregates used for asphalt?
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Nominal Max: one size larger than the first seive to retain more than 10% Maximum: one size larger than the nominal max size |
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How is performance grading symbolized? Explain each component. |
PG 64 - 22 "Performance Grade" Average 7-day max pavement temp. Minimum pavement temp. |
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What is Pavement Temperature a function of? |
Air temperature, Depth, Latitude |
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What is FATIGUE CRACKING? |
A series of interconnected cracks caused by failure due to repeated loading. |
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What were some early asphalt specifications and how have they advanced? |
Appearance, Consistency (chewing, penetration machine); Advancement: Viscosity specifications |
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How does asphalt differ from tar? |
Asphalt is a derivative of petroleum products while tar generally comes from coke (coal) production. Tar is resistant to petroleum products while asphalt is soluble in them. |
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What are the 3 types of asphalt? |
Asphalt cements, cutbacks, emulsions |
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What are the 3 categories of cutbacks? briefly describe each. |
1. Rapid Cure (RC): high volatility, used for tack coats
2. Medium Cure (MC): moderate volatility, used for stockpile patching mix 3. Slow Cure (SC): low volatility, used for prime coats, dust control. (environmental regulations are increasingly limiting the use of these products) |
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Briefly describe emulsions |
Mixture of asphalt cement, water, and emulsifying agent. Emulsifier gives surface charge to asphalt droplets suspended in water medium. 2 Types: -CATIONIC(Positive): silica gravels |
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What are the 2 components of asphalt? |
Asphaltenes (high viscosity component) & Maltenes (resins) |
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What are the 3 types of innovative mix designs/systems? |
1. Perpetual Pavement 2. Stone Matrix Asphalt 3. Open Graded Friction Course |
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Describe Perpetual Pavement. |
Combines the smoothness & safety advantages of asphalt with an advanced multi-layering paving process that extends the life of the roadway to half a century of more. Layers: -Intermediate layer (res. rutting) -Wearing surface (res top-down cracking, rutting) |
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Describe Stone Matrix Asphalt. |
Has a one size coarse aggregate gradation. High asphalt binder & high mineral filler content. -Rut resistant and durable -One major drawback is high cost. |
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Describe Open Graded Friction Course. |
Designed to have a large number of air voids so that water can drain through, and over, its surface. -Reduces the amount of splash/spray & glare from headlights during rain. -Noise reduction. |
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Briefly describe Mortar and what it is used for. |
A construction material formed by combining masonry units such as stone and brick with binding materials. -bonds units together -serves as a seating material -provides strength to the wall -provides aesthetic qualities |
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What are 2 types of mortar? |
1. Lime mortar (lime, sand, water) - hardens slowly, but has high workability and water retention. 2. Portland Cement (cement, sand, water) -poor workability & water retention, but hardens quickly and has high compressive strength & durability. |
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What are 5 types of masonry units? |
1. Concrete masonry units 2. Clay Brick 3. Structural Clay Tiles 4. Glass Block 5. Stone |
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What distinguishes hollow masonry units from solid units? Give an example of each. |
Hollow: net CS area < 75% gross CS area. -concrete blocks. Solid: net CS area > 75% gross CS area. -clay bricks. |
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What are some properties of concrete masonry units? |
-made of aggregate & cement -zero slump -molded under pressure -steam cured |
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What are the weight classes of concrete units? |
-Lightweight (easier handling & transportation, higher thermal resistance) -Medium weight -Normal weight |
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What are the two types of load bearing units for concrete? |
Type I: Moisture controlled Type II: Non-Moisture controlled |
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Durability is a function of _____________. |
Absorption. |
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Shrinkage is a function of _______________. |
Moisture content. |