CE Materials Final Exam
what is the relative temp that is commonly applied in the annealing of work hardened steel
.6T
What is the max amount of Silica Fume that is used in concrete
10
What is the modulus of steel at room temp?
29x10^6 psi
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
What are the 4 major types of glass fibers used in FRP
A, E, Z, S2
What is the formal ASTM designation for steel used today to make structural steel in hot rolled shapes?
A992
Besides silica what other metallic element is a primary component of most ceramics
Aluminum
List the initials of the 4 different compounds that exist in Portland Cement
C2S, C3S, C3A, C4AF
Which of the 4 compounds in portland cement grains must be kept very low percent to make the cement resistant to sulfate attack
C3A
What is the one compound in portland cement that is primarily responsible for long term strength gain of concrete?
C3S
When portland cement and water are mixed together, what is formed that gives the concrete its strength
CSH
What is the most important metal alloy in self weathering steel
Copper
What type of bond exist between the carbon atoms in the long polymer chain that makes the chain very strong in the line of the chain
Covalent
What is the principle metal alloy in stainless steel?
Cr
what are the 3 mechanisms by which water and chemicals penetrate into concrete
Diffusion, Adsorption, Permeation
What 2 types of FRP will suffer deterioration in moist and alkaline environments?
E glass, Polyester
T/F A characteristic of all metals is that metals have and endurance level for cylcycal loadings, below which repeated loadings will not cause metal failure even after many millions of loadings
F
T/F According to ASTM C-33, the fineness modulus of fine agg must be between 2.1 and 3.3
F
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
F
T/F An asphalt 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
F
T/F Brazing and sodering are very different processes; in brazing very hot temps are used to melt the members and joins them by the solidifying melted metal, but soldering is using different metal to join two other types of metals
F
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
F
T/F Class C Flyash has more silica but less calcium than does class F flyash, so class C can be used in greater % cement replacement than can Class F
F
T/F 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
F
T/F Creep limit stress level for concrete is 40% of f'c
F
T/F Flyash is the most effective SCM for reducing concrete permiability
F
T/F Heating an FRP from a temperature much below its Tg, to a temperature a little below the Tg will change the FRP from a brittle material to one that is pliable and stretchable
F
T/F In ceramic materials such as concrete the primary bonding type that holds atoms together is ionic bonding
F
T/F In the marshall test, the flow number is the maximum load that the asphalt sample supports and the stability is the deformation
F
T/F In the process of aging, the aluminum is reheated to a temperature of about 250 deg.C to cause very small particles of CuAl2 to coalesce and cluster together, which substantially improves the strength of aluminum and its ductility
F
T/F Iron at room temperature has face centered cubis structure
F
T/F Polymers that are used in FRP that are thermo-plastic are greatly affected by changes in temp, so their in-service condition should alway be a temp above the Tg so the FRP is not brittle
F
T/F Surface tension is the basic physical characteristic of a liquid that causes the phenomenon of absorbtion into a sand soil or paper towel
F
T/F The APF of body centered cubic structure is .64 and the APF of face centered cubic structure is .74
F
T/F The penetration test is preformed by measuring the depth that the needle will penetrate a small cup of asphalt in 5 seconds under the weight of 100g when the asphalt is at 77deg.c
F
T/F 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
F
T/F The slump of fresh concrete is always measures because it indicated directly if concrete has BOTH proper W/C ratio and proper workability
F
T/F To resist the effects of many cycles of freeze-thaw that will occur every winter season, air entraining agents must be used in concrete that will be outside throughout its life, and in eastern Mass there should be about 4% air in concrete
F
T/F Type IV cement should be used to make concrete that can resist sulfate attack when concrete will be embedded in sulfate rich soil
F
T/F Water reducing agents act to make concrete very fluid with less water, this improving workability but this will cause the concrete to take much longer to achieve its initial set and delays strength development
F
T/F When a metal cools from liquid to solid, the atomic rystal structure grows from many nucleation points , and these crystal structures usually line up and overlap with one another to form into lonly a few large uniformly oriented metal crystals
F
T/F When a pure metal is cooled slowly from liquid state, it will develop large crystal grain structure, and this will provide rather high yeild stress and low brittlenedd
F
T/F When a simply supported rectangular concrete beam is being reinforce with FRP to improve the beam's ability to carry bending moment, the fibers in the FRO 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
F
T/F When a steel beam is thoroughly heated to 850 def.F, it would be expected to have lost more than 50% of its yield strength
F
T/F When a steel element in a structure fractures, it is developing cracks, but when the steel fails, the cracks break through and the element seperates into two pieces
F
T/F When aggregate is at a water content greater than its SSD condition, then the amount of water that is put into concrete mix must be increased to maintain proper W/C ratio
F
T/F When bitumen oxidizes as it ages, oxygen molecules combine with the aromatics and resins to form asphaltenes which havea higher molecular weight and are harder than resins and oils, which makes bitumen harder and more resistant to cracking
F
T/F When the viscosity value of a liquid asphalt goes down, the marshal test strength parameter would also be expected to go down
F
T/F in superpave system, the PG that is used to designate the specific asphalt binder needed to make an asphalt concrete for highway stands for Pavement Grade
F
T/F the reason that metals expand when they are heated is that the added eneergy causes the nucleus of each atom to expand which causes atoms to vibrate and expand which causes the entire array of atoms to expand
F
Under impact loading at +80 deg F, the stiffness of a metal such as steel will be increased and its strength will be greatly increased
F
What is the phenomenon of an asphalt pavement suffering cracking failure after incurring several million repetitions of heavy trucks
Fatigue
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 as H2o within the C-S-H molecular structure
Hydrates / Water Crystallizatrion
Which of the following is NOT true about the effects of 'Strain, or work hardening' of a metal? -Increase strength -Increase modulus -Decrease ductility -increase brittleness
Increase modulus
Which is not one of the three sub divisions of creep deformation -Initial -Secondary -Tertiary
Initial
Cast iron products are more brittle than steel because cast iron contains much greater carbon content that often forms Fe3C during the slow cooling of iron, What are the two different names of Fe3C
Iron Carbide and Cementite
What is the name used to identify a Fiber reinforced Polymer that has the same strength and stiffness in all direction
Isotropic
What is the primary earth material needed and used in manufacturing cement
Limestone
Define 'gel'
Liquid with lots of fine particles so it is viscous
In the US the beam test is typicallt used to determine the flexural tension strength of concrete. What is the name of the property that is determined
Modulus of Rupture
4 of the environmental factors that can cause degradation of FRP materials are
Moisture, Corrosion, Thermal, UV
What size of US Standard sieve is used to seperate fine agg from fines
No. 200
When steel is heated and then rolled to make it make 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 -None of these
None of these
What are the names of the 2 different types of carbon fibers made for use in FRP
PAN, Pitch
What is viscosity a measure of?
Resistance to shear stress
2 major disadvantages that arise from working metals like steel by the hot working process
Shrinkage and surface rust
What are the four different elements that the earth materials provide, that are combined in the kiln and burned together in the process of making portland cement?
Si, Ca, Al, Fe
What is one element that all supplemental cementitious materials contain, that makes them valuable as replacement for some of the portland cement in concrete mixes?
Silica
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. What is the name of this load reducing phenomenon?
Stress Relaxation
what are the 2 principle failure modes that occur in a highway asphalt pavement
Structural, Functional
T/F A cylinder of concrete is really experiencing a form of tensile failure when loaded to failure under compression loading in a lab
T
T/F A metal is considered to be ductile when its toughness,GC, from the charpy test that is greater than 20J
T
T/F Aggregates that are silica based such as granite and quartzite do not preform 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
T
T/F Air entrainment protects concrete from freeze that deterioration by providing lots of 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
T
T/F Alloys are used in aluminum, because their inclusion increases the strength of aluminum by as much as 15 times greater than plain aluminum
T
T/F An elastomer will undergo elastic strain when 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 crosslinked so the molecules can not move irreversibly
T
T/F HDPE is a thermo-plastic polymer
T
T/F 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 the internal heat to anneal the grain structure
T
T/F In a plant that makes asphalt concrete for paving, the aggregates are heated to both dry them out and give heat needed for the asphalt concrete mixture, and then finally sprayed w hot asphalt and mixed for several minutes
T
T/F Metals that have BCC atomic structure will undergo plastic deformations in response to applied load, but those with HCP will not
T
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
T
T/F Solid aluminum always has face centered cubid structure
T
T/F The atomic packing factor is the ratio of the volume of atoms in the unit cell divided by the volume of the unit cell
T
T/F The primary problem for concrete that suffers carbonation is that the pH of HCP is reduced when CO2 attacks the Portlandite annd creates Ca(CO)3 and H2O
T
T/F The transition zone around coarse aggregate is a very thin zone that had high W/C, rich in Ca(OH)2 and ettringite, and contains very little C-S-H
T
T/F To achieve concrete that is very high strengthm the mix should have: silica fume, low W/C, high cement content, and clean crushed stone for coarse aggregate
T
T/F Viscosity of a liquid decreases when temp increases
T
T/F When a liquid has a low wetting contact angle, it will readily spread out over a large area?
T
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
T
T/F 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
T
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
T
T/F When molten low-carbon (0.2%) steel is cooled, austenite(having fcc atomic structure) forms first, and on furthur cooling, the austenite structure changes into a mix of ferrite and Fe3C
T
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
T
T/F in the strain hardening of metals, a large number of dislocations are forced toi move in the atomic structure, which results in plastic deformation of the metal and an increase in the proportional limit
T
T/F one of the most frequent atomic structures in ceramic materials is the silica tetrahedron
T
T/F the maximum amount of ground blast furnace slag that is allowed by ACI for use as an SCM in concrete for structures is 40%
T
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 Superposition Principle
Name the 4 types of atomic bonds
Vander waal/hydrogen, Ionic, metallic, covalent
What are the 4 types of cast iron
White, Grey, Malleable, Spheroidal
In a typical sacraficial metal protection systenm bars of what metal are buried in the ground as sacrificial anodes and connected with wires to a buried steel pipelines to keep the steel from rusting
Zinc
T/F Pearlite is the name given to the material formed of lamellae of Fe3C and austenite, the lamellae being nearly parallel in a laminated structure within grains of steel that is at room temperature
f
in using the electromotive series to select a sacraficial metal to protect another metal, the metal to be protected should have a HIGHER or LOWER electromotive value than the sacraficial metal
lower
T/F Both bolts and earlier used rivets have high strength and low stress relaxation, but they are both brittle and have low strain to failure
t
