CCE 3101 Final Exam
Bitumen
A class of black or dark-colored (solid, semisolid, or viscous) cementitious material (natural or manufactured) composed primarily of various mixtures of complex hydrocarbons
Flexibility
Ability of pavement to deflect (bend) and "flow" without cracking
Hygroscopic
Affinity for liquid of vapor
Binder tests to measure physical properties for SUPERPAVE mixes
Aims to mimic actual environmental and traffic conditions; Dynamic shear test, bending beam test, direct tension test, and durability tests.
Chromium and copper
Alter steel Corrosion Resistance
Chromium, nickel, manganese, and silicon
Alter steel Hardenability
Chromium and molybdenum
Alter steel Strength
Nickel and silicon
Alter steel Toughness
Sulfur
Alters steel Machinability and Ductility
Two main types of welding
Arc & Gas
Rapid-curing cutbacks
Asphalt mixed with an additive such as gasoline; evaporates fast
Medium-curing cutbacks
Asphalt mixed with an additive such as kerosene; medium rate of evaporation
Emulsified Asphalt
Asphalt mixed with water using an emulsifying agent; the emulsion involves ionic activities between the asphalt and water, leading to attraction between the two.
Slow-curing cutbacks
Asphalts mixed with an additive such as diesel oil; slow rate of evaporation
Pearlite
At 0.77% Carbon and below 727 degrees Celsius, product formed from alpha ferrite and iron carbide
Iron
Basic constituent of steel
Compressive failure parallel to the grain
Bending or buckling of wood fibers
Two primary causes of wood deterioration
Biotic (living) agents and physical (nonliving) agents
Loads parallel to the grain
Carried by the strongest of the wood fibers
Loads perpendicular to the grain
Carried by the weakest of the wood fibers
Electric Arc Furnace
Charge is mainly scrap metals with some iron ore and limestone added during the process; high temperature electric arcs generates high temperatures for melting and refining steel
Flash point test (ASTM D 92)
Cleveland open cup method; a test to measure the temp. at which the asphalt flashes or catches fire from an open flame; establishes a safety threshold temperature for fire hazard
Asphalt origin
Comes mostly from processing of crude petroleum
Compressive failure perpendicular to the grain
Complete crushing of wood fibers
Lignin
Component of wood that determines compressive strength
Cellulose
Component of wood that determines elastic properties
Conifer trees
Cone bearing; softwood; examples include pine, cedar, spruce, cypress, and redwood
Grades A242 and A588
Corrosion-resistant and high strength steels (expensive)
SUPERPAVE system
Designed to give better performance under extremes of temperature and heavy traffic loads; more rigorous than the Marshall Stability mix design approach
Viscosity vs. temperature relationship
Determines the temperatures for mixing aggregates and binder for placing and compacting in the field
Ductility Test (ASTM D113)
Distance of elongation before breakage; not an acceptable measure of elasticity
Wood seasoning
Done by air-drying or kiln-drying to stabilize wood behavior in the presence of moisture (avoid shrinking problems)
What are the two principal classes of trees?
Exogens & Endogens
Austenite
Ferrite changes to this at 912 degrees Celsius
Endogens
Few uses in construction; intermingle growth internally (old and new); examples include bamboo, sugar canes, and palm
Tubular cells
Filaments in long chains cemented by lignin, with small amounts of resin and gum (approx. 55% cellulose, 35% lignin)
Knots
Formed at the base of branches where they extend into the primary trunk of the tree; reduces bending strength (wood defect)
Compression wood
Formed on the lower side of the branches or leaning tree trunks (wood defect)
Checks, shakes, knots, compression wood
Four main defects in lumber
1. strength and stability 2. durability 3. flexibility 4. skid resistance
Four properties to be optimized when proportioning asphalt mixes
Two ways water exists in wood cells
Free water in cell cavities, bound water in cell walls
What are the two types of exogens?
Hardwood & softwood
Biotic agents
Include bacteria, fungi, insects, and marine borers. Some of these organisms use the wood as a food source, while others use it for shelter
Physical agents
Include mechanical abrasion or impact, ultraviolet light, metal corrosion by-products, and strong acids or bases. The ultraviolet portion of sunlight chemically degrades the lignin near the wood surface
Stress wave
Induced by striking the timber element with an impact device instrumented with an accelerometer that emits a start signal to a timer
Pig iron
Iron ore reduced to metal using blast furnaces
Deciduous trees
Leaves fall in winter; hardwood; examples include oak, maple, & hickory
Compressive strength parallel to the grain
Limiting factor in flexural strength of timber
Durability
Long-term resistance to deterioration
Checks
Longitudinal cracks across growth rings; occurs during the drying of timber (wood defect)
Shakes
Longitudinal cracks that follow growth rings (in between rings); occurs prior to cutting of logs. Attributed to heavy winds during storage (wood defect)
Coke
Made from coal or petroleum by thermal decomposition
Stability, density, % air voids, % voids in mineral aggregate (VMA), % asphalt content
Major characteristics of the compacted asphaltic concrete mixture
Consistency
Measure of hardness or softness
Absolute viscosity test (ASTM D 2171)
Measured in poise; asphalt is heated and poured into a vacuum capillary viscometer placed in water/oil bath at temperature of 140 F.
Kinematic viscosity test (ASTM D 2170)
Measured in stoke; similar to absolute viscosity test (ASTM D 2171) except that no vacuum is used and the bath temperature is 275 F; considers density; ratio of absolute viscosity to the density of fluid
Viscosity tests
Measurement of consistency of asphalt in the liquid state
Marshall Stability
Measurement of the resistance to plastic flow of cylindrical specimen of bituminous paving mixtures loaded on the lateral surface
Dynamic shear test (SUPERPAVE system)
Measures binder's stiffness at intermediate temperatures, indicating binder's ability to withstand rutting and fatigue cracks
Direct tension test (SUPERPAVE system)
Measures low temperature tensile and fracture properties; indicates low-temperature performance
Bending beam test (SUPERPAVE system)
Measures the low-temperature stiffness, used to predict low-temperature cracking
Steel Grade A36
Most common grade in buildings, bridges, transmission towers, and other structures
Blast Oxygen Furnace
Most popular method of producing steel; uses pig iron, limestone, and/or scrap metals as charge (raw material); Rapid oxidation of nonferrous elements (especially carbon)
Pitch origin
Obtained from further distillation of coal tar
Iron ores in earths crust
Oxides, carbonates, silicates, sulfides
High penetration
Penetration level for asphalts in cold regions
Low penetration
Penetration level for asphalts in warmer climates
Three factors that determine binder selection
Performance grade, specific gravity, viscosity vs. temperature relationship
Asphalt binder specification
Performance-grade specifications in SUPERPAVE, utilizes weather and pavement temp. to classify binders; for specific paving location
Three forms of reinforced steel
Plain bars, deformed bars, and wire fabrics
Combination of iron and carbon
Primary contents of steel
Coal tars origin
Produced from the destructive distillation of coal
Strength and durability
Properties that can be affected by defects in lumber
Alpha Ferrite
Pure iron flow 912 degrees Celsius
Hardening
Rapid cooling (quenching), creates strain in steel; must be tempered
Effective specific gravity
Ratio of the weight of an aggregate particle to the weight of a volume of water equal to the volume of the solid aggregate, pores impermeable to asphalt; SGe = (SGa + SGb) / 2
Apparent specific gravity
Ratio of the weight of an aggregate particle to the weight of a volume of water equal to the volume of the solid aggregate, pores impermeable to water
Bulk specific gravity
Ratio of the weight of an aggregate particle to the weight of a volume of water equal to the volume of the solid aggregate, pores impermeable to water and pores permeable to water
Open Hearth Furnace
Raw materials include same as Basic Oxygen Furnace; Charge is melted through open surface of flames from liquid fuel and gas with preheated air for combustion
Fiber saturation point
Reached when all free water is gone, leaving only bound water; wood volume has remained constant thus far, further drying will expel bound water and reduce the wood volume (shrinkage)
Tempering
Reheating hardened steel and cooling to increase ductility and toughness
Normalizing
Similar to annealing but different rate of cooling; effective for high fracture toughness
Considering stress waves, what varies with grain direction?
Speed of wave propagation
Torsion Test (ASTM E 143)
Steel test to determine shear modulus
Bending Test (ASTM E 290)
Steel test to evaluate ability of steel to resist cracking during bending (fabrication)
Rockwell Hardness Test (ASTM E 18)
Steel test to measure its resistance to localized plastic deformation (i.e. small dent or scratch) on surface
V-Notch Impact Test (ASTM E 23)
Steel test to measure toughness
Tension Test (ASTM E8)
Steel testing to determine engineering stress-strain curve, yield strength, yield point, ultimate tensile strength, etc
Welding
Technique for joining two metal pieces by applying heat to fuse the pieces together
Penetration Test (ASTM D5)
Test for consistency; Measured distance in units of 0.1 mm after 5 seconds of needle's vertical penetration on sample (Temp = 77 F) with applied load of 100 grams on the needle
Grain
The direction of the wood fibers
Asphalt curing
The process of the volatile oil eventually evaporating during asphalt modification
Slope of the grain
The tangent of the angle that a grain makes with the cut edge of the lumber
Rapid setting, medium setting, slow setting
Three types of emulsified asphalt
Compare wave transition times between parallel & perpendicular to the grain
Times are shortest parallel to the grain and longest perpendicular to the grain
Annealing
To refine grain, soften steel, remove internal stress, remove gases, increase ductility & toughness
Oxidation of asphalt and water penetration
Two causes of stripping and potholes
Tubular cells
Type of cells that make up wood
Specific Gravity Test (ASTM D70)
Use of pycnometer to determine specific gravity and density
Exogens
Used for most construction; grow along the diameter (annual rings)
Asphalt modification
Using additives to allow distribution and ease of placement (workability) of asphalt at reasonable temperatures
SUPERPAVE Gyratory Compactor
Volumetric proportioning of asphalt and aggregate; laboratory compaction; simulates the real-life effect of traffic loading on pavement by kneading the mix and compacting in a gyrating mold.
Quartersawn (rift cut)
Wood is cut radially or across the annual rings; warps less in drying process. Warping is unequal drying and shrinkage over the portions of lumber
Flatsawn (slash-cut)
Wood is cut tangentially to the annual rings. More susceptible to warping and shrinkage
Clear wood
Wood that has no defects
Stainless steel
high alloy content, used for serious corrosive environments