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