CE Materials Final

Q9: T/F, in the Marshall Test, the flow number is the maximum load that the asphalt sample supports in the test, and the stability is the deformation.

False (deformation=flow, max load=stability)

Q9: T/F, an asphalt pavement in Texas on a hot summer day can have a stiffness modulus that is 100 times smaller (softer) than would a similar asphalt pavement on a cold cloudy day in Chicago in the winter.

False (it's 10 times smaller)

Q9: T/F, the penetration test is performed by measuring the depth that the needle will penetrate a small cup of asphalt in 5 seconds under the weight of 100 grams, when the asphalt is at 77 degrees Celsius.

False (it's 77 degrees Fahrenheit... lame ikr)

Q8: T/F, fly ash is the most effective SCM for reducing concrete permeability.

False (silica fume)

Q9: T/F, in the SuperPave system, the PG that is used to designate the specific asphalt binder needed to make an asphalt concrete for paving a highway stands for Pavement Grade.

False (stands for Performance Grade)

Q8: T/F, when limestone coarse aggregate is used in a concrete, that concrete can experience rapid loss of strength when its temperature exceeds 450 deg C, and this is due to the large difference in thermal expansion between HCP and the limestone aggregate.

False (that happens above 500 deg C)

Q8: T/F, type IV cement should be used to make concrete that can resist sulfate attack when the concrete will be embedded in sulfate rich soil.

False (type V)

Q10: EXTRA CREDIT, find the tangent modulus of elasticity at 0.2% strain.

Find 0.2% strain, draw a tangent line that represents the slope at that point, find slope

Q8: What are two of the three primary ways that a concrete mix can be made to resist ASR when you must use aggregate that contains active silica?

Fly ash Low alkali cement (<0.6%) Control moisture availability

Q10: List four of the five different environmental factors that can cause degradation of FRP materials.

Freeze thaw Moisture/aqueous solutions UV Rays Fire Corrosion

Q10: What does the designation Tg stand for?

Glass setting temperature

Q2: Calculate the value of Poisson's Ratio for a metal under tensile load of 60,000 pounds. It is a round steel bar that is initially 1.25 inches in diameter and has a gage length of 4.0 inches. Under the load, the gage length increased to 4.0134 in. and diameter decreased to 1.2485 in.

Lateral strain over Axial strain [(0.0015)/(1.25)]/[(0.0134)/(4)] = 0.3581

Q10: T/F, HDPE is a thermo-plastic polymer.

True

Q10: T/F, heating an FRP from a temperature much below its Tg to a temperature a little below the Tg will chane the FRP from a brittle material to one that is pliable and stretchable.

True

Q1: True or False ? - A cylinder of concrete is really experiencing a form of tensile failure when loaded to failure under compression loading in laboratory.

True

Q1: True or False ? - Nominal stress, which is also referred to as engineering stress, will be less than the "true stress" in a metal bar being loaded in tension.

True

Q1: True or False ? - When an iron rod is tested in tension, and the fracture surface shows no necking down and sharp fracture through the bar at right angle to the applied load, this represents a very brittle material behavior.

True

Q2: True or False ? - A metal is considered to be ductile when it has toughness, Gc, from the Charpy test that is a value greater than 20 J.

True

Q2: True or False ? - One of the most frequent atomic structures in ceramic materials is the silica tetrahedron.

True

Q2: True or False ? - Solid aluminum always has face-centered cubic structure.

True

Q2: True or False ? - The Atomic Packing Factor is the ratio of the volume of atoms in the unit cell divided by the volume of the unit cell.

True

Q3: True or False ? - In the strain hardening of metals , a large number of dislocations are forced to move in the atomic structure, which results in plastic deformation of the metal and an increase in the proportional limit.

True

Q3: True or False ? - Metals that have BCC atomic structure will readily undergo plastic deformations in response to applied load, but those with HCP will not.

True

Q3: True or False ? - When a liquid has a low wetting contact angle, Theta, it will readily spread out over a large area.

True

Q8: T/F, air entrainment protects concrete from freeze-thaw deterioration by providing lots of air bubbles that are 1/100 the size of entrapped air voids, so the expansive force of freezing water is relieved by freezing water moving into the tiny voids.

True

Q8: T/F, the transition zone around coarse aggregate is a very thin zone that has high w/c ratio, is rich in Ca(OH)2 and ettringite, and contains very little CSH.

True

Q8: T/F, to achieve concrete that is very high-strength, the mix must have: silica fume, low w/c ratio, high cement content, and clean crushed stone for coarse aggregate.

True

Q9: T/F, aggregates that are silica based such as granite and quartzite do not perform as well in asphalt as does carbonate rocks such as limestone because the asphalt does not adhere very good to silica minerals, but does stick well to carbonate-rich limestone.

True

Q9: T/F, in a plant that makes asphalt concrete for paving, the aggregates are heated thoroughly to both dry them out and give heat needed for the asphalt concrete mixture, and then finally sprayed with hot asphalt and mixed for several minutes.

True

Q9: T/F, in the SuperPave system, the asphalt binder used to make the asphalt concrete is designated by PG numbers that are based on the temperature range that the pavement is expected to experience throughout its life.

True

Q9: T/F, when the viscosity value of a liquid asphalt goes down, the Marshall Test strength parameter would also be expected to go down.

True

Q1: Circle the name that is not one of the three different sub-divisions of creep deformation? a) Initial b) Secondary c) Tertiary

a) Inital

Q2: Write the names of four different types of defects and impurities that occur in the crystal structure of metals, and which have large effect in determining the strength of metals.

a) Interstitial b) Vacancy c) Edge d) Substitutions

Q2: a) What is the name of the behavior where in hot solid iron changes its atomic structure when cooled? b) At what temperature does this change in solid iron occur?

a)Alotrophic b) 910(Celsius)

Q3: A 50 ft. long steel beam has an area of 100 sq.in. and heats up from winter to summer and would want to elongate by 0.55 inches. How much load would be needed to hold the beam and prevent it from elongating?

((Delta)(A)(E))/(L) ((0.55)(100)(20x10^6))/(50) = 2,658,333(lbs)

Q5:A piece of metal that is 1 inch diameter and 2 inches long is loaded axially and shortens to 1.992 inches, and expands radially to 1.001 inches. What is it its Poisson's Ratio?

(0.001/1)/(0.008/2) = 0.25

Q7: What is the primary performance reason that chert is not a good material to have in the coarse aggregate used to make concrete for the exterior of a building?

-Chert is porous, freeze-thaw will be an issue, will cause popouts -Low specific gravity

Q8: Describe how the ASR (alkali silica) reaction in concrete causes damage to concrete.

-Gel forms, that can break the aggregate-HCP bond -When the gel swells, it can cause cracking

Q7: List four different ways that bleeding of concrete can be effectively reduced.

-Have proper aggregate gradation -Control water input -Maintain at normal temperature -Mix concrete well -Lower w/c ratio -Use water reducer -Silica fume -Super plasticizers -Air entraining agent

Q1: What are the names of the four different types of bonds between atoms?

-Ionic -Covalent -Metallic -Vander Waals

Q7: When bleed water from fresh concrete encounters horizontal rebar as the water migrates up to the surface of freshly placed concrete, what major problem may develop?

-Rust and corrosion of the rebar -Increases w/c ratio, reduces compressive strength

Q6: What is the maximum amount of silica fume that is used in concrete?

10%

Q1: Determine by calculation, what is the value of the secant modulus up to 100,000 psi for the stress vs. strain graph shown on attached Figure 16.

100,000/($0.327) $Estimated off Graph

Q7: What is the minimal amount of time that a concrete structural element made with ggbs as SCM in the concrete mix must be kept moist to insure proper curing and strength?

21 days

Q5: What is the modulus of elasticity of steel at room temperature?

29 x 10^6 psi

Q1: What is the value of the modulus of elasticity of steel?

29x10^6 psi

Q4: What is the "relative temperature" that is commonly applied in the annealing of work-hardened steel?

60% of the melting temperature

Q7: What is the normal amount of time that a concrete structural element made with "normal" concrete must be kept moist to insure proper curing and strength gain?

7 days

Q3: Define what a "gel" is.

A liquid with fine particles suspended in it.

Q5: What is the formal ASTM designation for steel used today to make structural steel in hot-rolled shapes?

A-992

Q6: Explain one fundamental thing that air entraining agents do to make concrete resistant to the otherwise damaging effects of winter freeze-thaw.

Allows free water to expand into the air voids, prevents stresses that would happen from water freezing (it would expand)

Q3: Explain what is the primary benefit to the behavior of the eventual solid metal of including small amounts of an alloy element in the melted metal before making the casting.

Alloys allow for small disruptions making metal more ductile.

Q5: Explain the fundamental reason why aluminum should not be embedded in concrete.

Aluminum's oxide coating has an operating pH range of 4-8. Concrete's pH is 12-13. CTE (coefficient of thermal expansion) is higher in aluminum and will swell up more during changes in temperature than steel will in concrete

Q3: Determine by calculation, what is the value of the secant modulus up to a tensile stress of 70,000 psi for the stress vs. strain graph shown on the attached Figure 3.

At the peak of the stress strain graph tensile stress is 70,000 and axial strain is 0.4%. (70,000/0.004) = 17,500,000(psi)

Q5: What are four different properties that are necessary for steel rebar to have?

Bendability, Weldability, Resistance to corrosion, Resistance to fatigue, Surface hardness, Fracture resistance

Q6: When Portland Cement and water are mixed together, what is formed that gives concrete its strength?

C-S-H

Q6: What is one compound in Portland Cement that is primarily responsible for LONG-TERM strength gain of concrete?

C2S

Q6: Which one of the four compounds in Portland Cement grains must be kept very low percentage to make the cement resistant to sulfate attack?

C3A

Q6: List the initials of the four compounds that exist in each grain of Portland Cement.

C3S C2S C3A C4AF

Q7: Write the equation for the carbonation reaction that occurs in concrete exposed to the atmosphere.

CO2 + Ca(OH)2 --> H2O + CaCO3

Q6: What are four different elements that the early materials provide, that are combined in the kiln and burned together in the process of making Portland Cement?

Ca Al Si Fe

Q7: What are three of the primary reasons why excessive amount of soil fines is very undesirable in concrete aggregate?

Can lead to bleeding Fines will clump together Will absorb too much water Coats coarse aggregate Poor bond

Q7: List the four different sources of drying concrete shrinkage?

Capillary tension Movement of interlayer water Disjoining membranes Evaporation Bleeding

Q8: What is the primary reason that rebar is at high risk of corrosion when concrete has suffered carbonation?

Carbonation lowers the pH below 11

Q4: What is the primary reason that the amount of Fe3C in structural steel must be kept to a very low percentage?

Cementite is very brittle, so ductility in Fe3C is low.

Q9: What are the three different types of mineral aggregates that are used in making asphalt concrete for paving?

Coarse aggregate Fine aggregate Filler

Q10: What type of bond exists between the carbom atoms in a long polymer chain that makes the chain very strong in the line of the chain?

Covalent

Q1: Which type of atomic bonding occurs when one atom "shares" one or more electrons from another atom of the same element?

Covalent

Q5: Which one of these is the principal metal alloy in stainless steel? Zn, Sn, Cu, Cr, Mn, None of these

Cr

Q5: Which ONE of these is an important metal alloy in self weathering steel. Cr, Sn, Cu, Zn, Mg, or none of these

Cu

Q1: Make a sketch of the fracture surface you would expect to occur for a metal that suffered a moderately ductile type of failure.

Cup and Cone fracture: ____ ____ ____) )___ (It costs money to upload a pic, this is the best I could do)

Q9: There are three different types of asphalt. How is each softened for making pavement asphalt? -cutback -emulsion -penetration grade

Cutback: mix with solvent Emulsion: water+emulsifier Penetration grade: higher temperature

Q2: Describe the one physical condition in metals that makes the actual tensile strength be only about 10% of the theoretical atomic strength that would be calculated based on inter-atomic force attraction and repulsion.

Defects in crystalline structure.

Q7: EXTRA CREDIT, write the equation for determining the elastic modulus of concrete.

Ec = 57600 x sqrt(f'c)

Q5: What is the atomic structure of aluminum? HCP, BCT, FCC, or BCC?

FCC

Q3: True or False ? - The reason that metals expand when they are heated is that the added energy causes the nucleus of each atom to expand which causes atoms to vibrate and expand which causes the entire array of atoms to expand.

False

Q3: True or False ? - Within a single grain of metal, there can be thousands of edge dislocations that move when shear stress is applied. But because grain boundaries blocks the dislocation movements, metal having big grains and few boundaries will make for stiffer, less ductile behavior, so metals with larger grains will be stiffer than the same metal with small grains.

False

Q4: True or False ? - Brazing and soldering are very different processes: in brazing very hot temperatures are used to melt the members and join them by the solidified melted metal, but soldering is using different metal to join two other types of metal.

False

Q4: True or False ? - Cold-rolled steel products have an increase in strength from undergoing strain hardening, but they lose ductility and become brittle due to the intense squeezing of the grains of the original steel, but this problem does not occur in hot-rolling.

False

Q4: True or False ? - Pearlite is the name given to the material formed of lamellae of Fe3C and austenite, the lamellae being nearly parallel in laminated structure with grains of steel that is at room temperature?

False

Q4: True or False ? - Steel corrosion occurs in a wet environment when electrons of iron are conducted through the steel to a place where they are consumed in a reaction with oxygen to form iron oxide ions, known as ferrous-oxide in the electron-depleted metal, and then further reacts further with water and oxygen to create fully corroded ferrous-hydroxide.

False

Q4: True or False ? - The rapid cooling of melted metal that forms from welding causes large grains of Fe3C to form which makes the weld very strong but very brittle

False

Q5: (True / False ) When a steel beam is thoroughly heated to 850 degrees F, it would be expected to have lost more than 50% of its yield strength.

False

Q5: (True / False) In the process of "ageing", the aluminum is reheated to a temperature of about 250 degrees C to cause very small particles of CuAl2 to coalesce and cluster together, which substantially improves the strength of aluminum and its ductility.

False

Q6: T/F, calcium chloride is often used as an accelerating agent to speed up concrete setting, and is effective in reinforced concrete because it greatly improves the bond of the concrete to the reinforcing steel bars.

False

Q6: T/F, class C flyash has more silica but less calcium than does class F flyash, so class C can be used in greater percent cement replacement than can class F.

False

Q6: T/F, to resist the effects of many cycles of freeze-thaw that occur every winter season, air entraining agents must be used in concrete that will be outside through its life, and in eastern Mass there should be about 4% air in concrete.

False

Q6: T/F, water reducing agents act to make concrete very fluid with less water, thus improving workability, but this will cause the concrete to take much longer to achieve its initial set and delays strength development.

False

Q7: T/F, alkali-silica reaction occurs when the silica of the concrete's C-S-H reacts with certain alkaline minerals in bedrock that is crushed for coarse aggregate.

False

Q7: T/F, the slump of fresh concrete is always measured because it indicates directly if concrete has both proper w/c ratio and proper workability.

False

Q7: T/F, according to ASTM C-33, the fineness modulus of fine aggregate must be between 2.1 and 3.3.

False (2.3-3.1... seriously??)

Q7: T/F, when aggregate is at a water content greater than its SSD condition, then the amount of water that is put into the concrete mix must be increased to maintain proper w/c ratio.

False (you'd add less water)

Q3: True or False ? - When a pure metal is cooled slowly from the liquid state, it will develop large crystal grain structure, and this will provide rather high yield stress and low brittleness.

False (It will be Ductile)

Q9: What is the name given to the phenomenon of an asphalt pavement suffering cracking failure after incurring several million load repetitions of heavy trucks?

Fatigue failure Structural deterioration

Q5: What are the names of the 3 different types of stainless steel? Which one can be welded?

Ferrittic, Austenitic, and Martensitic. Austenitic can be welded

Q6: What is the effect of each of the three primary SCMs used in the US on the workability of a concrete mixture? -flyash -ggbs -silica fume

Flyash: increase ggbs: increase Silica fume: decrease

Q10: What two types of fibers in FRP will suffer deterioration in moist and alkaline environment?

Glass Aramid

Q6: EXTRA CREDIT, what is another way to speed up the hydration of cement, other than altering the relative amounts of the four primary compounds?

Grind into finer pieces

Q6: What types of cement (I, II, III, IV, V) are need to: -have high early strength -give low heat of hydration

High early strength = III Low heat of hydration = IV

Q7: List four different ways that fresh concrete might lose its consistence or workability.

High temperature Alkali-silica reaction Below freezing temperature Low w/c ratio Evaporation

Q10: List the two principal major benefits of using fibers in the polymer matrix material.

Increased strength Increased stiffness

Q10: What is the name used to identify an FRP that has THE SAME strength and stiffness in all directions?

Isotropic

Q6: Describe why ggbs must be flash cooled, or quenched, to make it useable as a replacement for some Portland Cement.

It needs to be hard, have coarse properties

Q8: Explain the details of how silica fume acts to greatly reduce the permeability of concrete.

It's very fine, makes the concrete dense which will decrease permeation

Q7: Describe two ways that you can minimize the alkali-silica reaction in a concrete if the only coarse aggregate that you have to use is an ASR reactive aggregate.

Keep concrete as dry as possible Pozzolans Fly ash Low alkali cement

Q4: In using electromotive series to select a sacrificial metal to protect another metal, the metal to be protected should have HIGHER or LOWER electromotive value than the sacrificial metal.

LOWER

Q5: What problem can be prevented by the proper design of welds required for building up weld material used to join together thick steel plate pieces?

Lamellar tearing

Q6: What is the primary earth material needed and used in manufacturing cement?

Limestone

Q5: Describe what is the most important precaution that must be followed when fastening aluminum parts together with steel bolts and rivets.

Make sure there is separation between the aluminum and steel to avoid corrosion.

Q7: What size of US standard sieve is used to separate fine aggregate from fines?

No. 200

Q5: When steel is heated and then rolled to make it into rebar, what is the name of the steel that forms at the rebar surface as a result of the water spray quenching process? Austenite, Ferrite, Cementite, Iron Carbide, or None of these

None of these - It's actually martensite

Q5: Explain what pearlite is, and how it is formed.

Pearlite is a very hard formation of steel that typically occurs at welds due to heat, and is a combination of layered ferrite and cementite.

Q9: List the two principal "failure" modes that occur in a highway asphalt pavement.

Permanent deformation (rutting) Cracking

Q8: List the three fundamental "mechanisms" by which water and chemicals penetrate into concrete.

Permeation Diffusion Sorption

Q3: Poisson's Ratio of a metal is 0.28. The metal is a rod that is 4.0 in. long and 0.25 inch diameter. Under tension load the rod stretches to be 4.0861 inches long. What will be its diameter in the stretched condition?

Poisson's Ratio = Lateral Strain / Axial Strain 0.28 = Lateral Strain/(0.0861/4) Poisson's Ratio x Axial Strain = Lateral Strain 0.28((0.0861)/(4)) = 0.006 Deformation/Diameter = Diameter Stretched 0.006/0.25 = 0.0241"

Q2: What is the stress value of the proportional limit and yield point for the stress vs. strain graph shown on the attached Figure 20.

Proportional limit when linear stops. Yield point peak of first hill. Proportional limit = 120(ksi). Yield point = 145(ksi).

Q10: What is the name of the commonly used process to make wide flange beams and other structural members from FRP?

Pultrusion

Q6: What is one element that all SCM contain, that makes them valuable as replacement for some of the Portland Cement in concrete mixes?

Silica Calcium

Q7: What are four different methods that are commonly used to keep concrete moist while it is curing?

Spray with water Cover with wet sheet/burlap Protect from sun/wind Resin membrane

Q4: What is the one big problem with the H.A.Z. and why does it occur?

Steel gets very hot around the weld and suddenly cools, Austenite becomes brittle Ferrite.

Q4: When red-hot steel is quenched, what is the result in terms of ductility and strength? Strength: LOW or HIGH Ductility: LOW or HIGH

Strength: HIGH Ductility: LOW

Q5: Explain why very high strength steel wire and cable (fy>150ksi) used in construction is not tempered to return it to a ductile condition.

Tensile forces within the wire would be brittle.

Q10: What is the name of the method used to accelerate testing of new FRP materials to make sure that the new material will have acceptable performance over its full design life?

Time temperature super position

Q5: As the temperature of steel increases from -30 degrees C to over +40 degrees C, what happens to the following properties? Toughness -- INCREASES -- NO CHANGE -- DECREASES Yield stress -- INCREASES -- NO CHANGE -- DECREASES Ductility -- INCREASES -- NO CHANGE -- DECREASES

Toughness: INCREASES Yield stress: DECREASES Ductility: INCREASES

Q10: T/F An elastomer will undergo elastic strain when a stress is applied, but it will recover all of the strain when the stress is removed, because such a polymer is made of long-chain molecules that are coiled and twisted and cross-linked so the molecules cannot move.

True

Q3: True or False ? - Viscosity of a liquid decreases when temperature increases.

True

Q4: True or False ? - Both bolts and earlier-used rivets have to have high strength, and low stress-relaxation, but they are both brittle and have low strain to failure.

True

Q4: True or False ? - Hot-working steel by rolling structural shapes at 1000 deg.C will cause great deformations in the grain structure, but this is generally relieved by leaving beams to cool naturally, which allows time for internal heat to anneal the grain structure.

True

Q4: True or False ? - When molten low-carbon (0.2%) steel is cooled, austenite (having face-centered cubic atomic structure) forms first, and on farther cooling, the austenite structure changes into a mix of ferrite (that is body-centered cubic) and Fe3C.

True

Q5: (True / False) Alloys are used in aluminum, because their inclusion increases the strength of aluminum by as much as 15 times greater than the strength of plain aluminum.

True

Q6: T/F, silica fume particles are very small compared to cement grains, and fit in the tiny spaces between cement grains and react very fast, so that within 2-4 weeks of hydration start, the silica fume action is completely finished.

True

Q6: T/F, the maximum amount of ggbs that is allowed by ACI for use as an SCM in concrete for structures is 40%.

True

Q7: T/F, when aggregate is at its SSD condition (saturated surface dry), the interior voids will be filled with water and the surface will be slightly damp.

True

Q8: T/F, the primary problem for concrete that suffers carbonation is that the pH of HCP is reduced when CO2 attacks the portlandite and creates CaCO3 and H2O.

True (portlandite = crystalline form of carbon hydroxide)

Q3: What is the name for the H2O molecules that react with the chemicals of cement grains to form hardened concrete gel known as Calcium Silicate Hydrate in which these molecules remain H2O within the C-S-H molecular structure.

Water of Crystalization

Q6: Describe how super plasticizers act in a concrete mix to greatly improve fluidity.

Works by attaching to the cement grains, giving the surfaces a negative charge, the grains will repel because of like charges, this releases water that may have been trapped

Q10: Of the four types of glass fiber, which is most often used when placed in concrete because of its resistance to alkali?

Z-glass

Q4: In a typical sacrificial metal protection system, bars of what metal are buried in ground as sacrificial anodes and connected with wires to a buried steel pipelines to keep the steel from rusting away?

Zinc

Q4: Describe what are the two major disadvantages that arise from working metals like steel by the hot working process.

a) Contraction when cooled b) Surface corrosion

Q4: Cast iron products are more brittle than steel because cast iron contains much greater carbon content that often forms hard Fe3C during the slow cooling of the iron. What are two different names of Fe3C.

a) Iron Carbide b) Cementite

Q4: List the 4 different ways to treat hot-rolled steel to relieve effects of hot-working.

a) Normalizing b) Quenching & Tempering c) Rolled d) Processed Normalization

Q4: List the common names of the four different types of cast iron. Q4: Circle the one type of cast iron you listed in No. 8 that is the most ductile?

a) White Iron b) Gray Iron c) (*Malleable*) d) Spheroidal graphite

Q7: Calculate length change due to temperature, concrete. 120' long 40 deg C -> 5 deg C

delta = (alpha)(delta T)(L) delta = (10x10^(-6))(5-35)(120) delta = -0.042ft

Q8: T/F, creep limit stress level for concrete is 40% of f'c.

False (45%)

Q2: Besides silica, what other metallic element is a primary component of most ceramics?

Aluminum

Q9: List the names of the three main components of bitumen, and give brief description of each.

Asphaltenes: Highest molecular weight Resins: maltenes, lower molecular weight, hydrocarbon chains Oils: maltenes, saturates and aromatics, long chains of molecule

Q10: To achieve maximum FIBER stress utilization in a polymer matrix, what is the minimum length that the fibers must have?

At least double the critical length

Q1: Calculate the Poisson's Ratio of a metal that is put under a tension loading and undergoes an axial strain of +0.089 in./in. and experiences lateral strain of - 2.4%.

Delta-Lateral over Delta-Axial (0.024)/(0.089) = 0.269

Q10: What are the names of the four major types of glass fibers used in FRP?

E-glass A-glass Z-glass S2-glass

Q9: What part of the asphalt making and paving process is the rolling thin film oven test used to replicate?

Early aging

Q2: Explain the one reason why, on the atomic crystal basis, that when a metal experiences a small load in tension, it deforms elastically, has no plastic deformation and will return to its original length when load is removed.

Edge defects are not forced to jump.

Q10: T/F, polymers that are used in FRP that are thermo-plastic are greatly affected by changes in temperature, so their in-serivce condition should always be at temperatures above the Tg so the FRP is not brittle.

False

Q10: T/F, when a simply-supported rectangular concrete beam is being reinforced with FRP to improve the beam's ability to carry bending moment, the fibers in the FRP used for the strengthening should be isotropic and should be placed along the bottom of the beam and oriented parallel to the long axis of the beam.

False

Q1: True or False ? - A characteristic of all metals is that metals have an endurance level for cycled loadings, below which repeated loadings will not cause metal failure even after a many millions of load cycles.

False

Q1: True or False ? - In ceramic materials such as concrete, the primary type of bonding that holds the atoms together is ionic bonding?

False

Q1: True or False ? - The term valence electron of an atom refers to only those electrons in the outer orbit of an atom that can be used to fill outer orbits of other atoms.

False

Q1: True or False ? - Under impact loading at +80 deg F, the strength of a metal such as steel , will be increased

False

Q2: True or False ? - Iron at room temperature has face-centered cubic structure.

False

Q2: True or False ? - The APF for body-centered cubic structure is 0.64 and the APF for face-centered cubic structure is 0.74.

False

Q2: True or False ? - When a metals cools from liquid state to solid, the atomic crystal structure grows from many nucleation points, and these crystal structures usually line up and overlap with one another to form into only a few large, uniformly oriented metal crystals.

False

Q2: True or False ? - When a steel element in a structure fractures, it is developing cracks, but when the steel element fails, the cracks break through and the element separates into two pieces.

False

Q3: True or False ? - Surface Tension is the basic physical characteristic of a liquid that causes the phenomenon of adsorption into a sand soil or paper towel.

False

Q9: T/F, asphalt pavement will suffer less deformation cracking when the temperature of the pavement is cold in the winter months, because the asphalt is stiffer and more capable of acting like a stiff beam under wheel loads.

False

Q9: T/F, when bitumen oxidizes as it ages, oxygen molecules combine with the aromatics and resins to form asphaltenes which have a higher molecular weight are are harder than resins and oils, which makes bitumen harder and more resistant to cracking.

False

Q3: A steel beam is 90 ft. long when its temperature is 55C. Beam cross-sectional area = 96 sq.in. The modulus of elasticity of the steel is 29x10^6 psi. The coefficient of thermal expansion of steel is 13.5x10^-6 in./in./deg.C. How long is the beam when it's temperature is -10C on a cold winter day?

Length x DeltaTemp x Alpha (90x(12in/1ft))x(65)x(13.5x10^-6) = 0.9484

Q3: What is viscosity a measure of?

Liquids resistance to shear stress

Q1: A tensile load of 37,000 pounds is applied to a square steel bar that is 0.50 inches in cross-section dimension and has a gage length of 3.5 inches. Under this load, what is the tensile stress in the steel bar?

Load over Area. 37,000/(0.5x0.5) = 148,000(psi)

Q8: What are three of the four component changes needed in making concrete that will last a long time when it will be in a SULPHATE-RICH environment throughout its service life?

Low w/c ratio Low C3A content Use fly ash Increase cement content

Q3: Explain why it is much easier for heat to be transferred through metals than through ceramic materials. Base your answer on an explanation of the principal atomic difference between ceramics and materials.

Metals have metallic bonds, which are weaker than Ceramics which has ionic and covalent bonds. Heating causes vibrations which are excitement in atoms, it is easier for vibrations to occur with weaker bonds.

Q8: In the US, the beam test is typically used to determine the flexural tension strength of concrete. What is the name of the property that is determined, according to US concrete design practice?

Modulus of rupture

Q10: List three different polymers that are thermo-setting.

Nylon Polyester Polyethylene Epoxies Vulcanized rubber

Q8: List the following information for each stage of cracking development in concrete.

ORDER = Stage 1 / Stage 2 / Stage 3 / Stage 4 Stress range: 0-30% / 30-50% / 50-75% / 75%+ Location of cracking: transition zone / transition zone / matrix, HCP / everywhere Type and amount of strain: elastic / plastic / plastic / plastic (strain increases more and more as the stages progress)

Q10: What are the names of the two different types of CARBON fibers made for use in FRP?

PAN PITCH

Q10: Of the type types of CARBON fiber, which is the most often used FRP in civil construction?

PITCH

Q9: EXTRA CREDIT, list the names of the six different lab tests that are done in the SuperPave PG asphalt grading system.

Rolling thin film oven Pressure aging vessel Rotational viscometer Dynamic shear rheometer Bending beam rheometer Direction tension

Q9: List two of the three primary functions of the top-most layer of an asphalt pavement

Skid resistance Resist abrasions Disperse load/stress Prevents water penetration

Q1: Creep deformation also manifests itself as the physical cause for a material to slowly lose load when that material is loaded to a pre-determined strain and held at that strain, such as a torqued bolt. What is the name of this load reducing phenomenon?

Stress Relaxation

Q8: In making self-compacting concrete, what are three very essential ingredients that must be included?

Super plasticizer Fine aggregate / fine material (like fly ash) Lower coarse aggregate volume <0.4 w/c ratio Viscosity enhancer

Q1: Which of the following is not true about the effect of "strain, or work hardening" of a metal? a) Increases strength b) Increases modulus c) Decreases ductility d) Increases brittleness e) All are True

b) Increases modulus

Q8: Calculate elongation due to temperature change. 1' thick, 12' wide, 70' long 60 deg F -> 120 deg F alpha = 8x10^(-6) in/in/degF

delta = (alpha)(delta T)(L) delta = (8x10^(-6))(120-60)(70ft)(12in/ft) delta = 0.403in

Q8: EXTRA CREDIT, calculate load that will develop due to restrained ends (can't expand the delta amount), concrete 18" thick, 10' wide, 60' long delta = 0.82"

delta = PL/AE P = (delta)(AE)/L P = (0.82)(18")(10ft)(12in/ft)(3.6x10^6)/[(60ft)(12in/ft)] P = 8856 kips

Q3: Draw a typical stress vs. strain graph for a visco-elastic material that is subjected to a constant load.

stress on y axis strain on the x ____ / It has an elastic portion and then a flat line, which is a viscous area.

Q2: A tensile load of 65,000 pounds is applied to a round metal bar that is 0.625 inches in diameter and has an initial gage length of 2.00 inches. Under this load, the gage length is increased to be 2.01834 inches. What is the modulus of elasticity of the metal bar (in psi)?

stress over strain ((65,000)/(pi/4)(0.625)^2)/(2.01834-2) = 3,104,388(psi)