Material Exam 1
(B) The S.S.D. bulk specific gravity Bulk SSD Sp. Gr. = S / B+S-C B = Mass of Pycnometer filled with water to calibration mark, g C = Mass of Pycnometer with sample and water to calibration mark, g S = Mass of saturated surface dry sample, g
(B) the S.S.D. bulk specific gravity
(C) The absorption of an aggregate from the raw laboratory data. SSD Weight - Oven Dry Weight / Oven Dry Weight * 100%
(C) the absorption of an aggregate from the raw laboratory data.
A: For determining mass/volume relationships B: g/cm3 C: The density of the aggregate D: Depends on the aggregate
Describe (A) the purpose of the test, (B) how the test results are reported, (C) the meaning of the test results, and (D) the typical threshold test values (if any) required in material specifications, for each of the following tests on aggregates: Bulk Unit Weight Test
Don't store in high cone shaped pile Don't let aggregate run down slope Avoid blowing wind Use of smaller but more piles Flat pile of larger area but lower height
Describe a few principles which could be followed to reduce segregation of aggregate during handling and storing.
Old concrete crushed to proper gradation can be used as aggregate but the strength and durability of the new concrete is limited by that of the old concrete. Higher absorption, lower specific gravity, lower strength are properties of recycled concrete
Describe the typical properties of recycled concrete as aggregate, and the properties of concrete made with recycled concrete.
To allow concrete to crack at the joint rather than randomly
The main purpose of a control joint in a concrete structure is:
Rough textured and angular aggregates give better bonding and higher strength but require more water to produce the same workability, but becomes weaker. Flat and elongated particles are undesirable.
What are the effects of particle shape and surface texture of aggregate on the properties of fresh and hardened concrete?
The aggregate bonds to the cement paste to make concrete stronger. Concrete cannot be stronger than its aggregate.
What are the functions of aggregate in concrete?
10^9 Giga 10^6 Mega 10^3 Kilo 10^-2 centi 10^-3 milli 10^-6 micro 10^-9 Nano
What are the standard prefixes for the tens?
(Types IS) - a blend of Portland cement with 25 to 70% by weight of granulated blast furnace slag.
What is a Portland-blast-furnace-slag cement?
1 g/cm^3 =62.4 lbm/ft^3
What is the density of water in both units?
Hydraulic Cement: hardens reacting with water, forming a water resistant product Non-Hydraulic Cement: reacts with water to form a non-stable product in water; the hydration product then reacts with air to for a water-resistant product Portland cement is a hydraulic product.
What is the difference between a hydraulic and a non-hydraulic cement? Is Portland cement a hydraulic cement?
Water content
What is the most important factor affecting the slump of of a fresh concrete?
A: Tests significance in determining the acceptability of aggregate B: As a percent by weight D: Allowable limits: 3% for fine aggregate and 2-10% for coarse aggregate
Describe (A) the purpose of the test, (B) how the test results are reported, (C) the meaning of the test results, and (D) the typical threshold test values (if any) required in material specifications, for each of the following tests on aggregates: Clay Lumps and Friable Particles in Aggregate
A: To determine the quality of a cement with regards to its rate of setting B: In initial and final setting time in minutes C: Quality D: ASTM C150 specification on time of setting: Min. Initial setting time = 60min Max Final setting time = 600min
Describe (A) the purpose of the test, (B) how the test results are reported, (C) the meaning or significance of the test results, (D) the typical threshold test values (if any) required in cement specifications for each of the following tests on Portland cement: Gillmore
A: To measure the heat of hydration at 7 days and at 28 days B: In cal/g or kJ/kg C: can provide information for calculating temperature rise in mass concrete D: Max of 60cal/g at 7 days and 70cal/g at 28 days for Type IV Portland cement
Describe (A) the purpose of the test, (B) how the test results are reported, (C) the meaning or significance of the test results, (D) the typical threshold test values (if any) required in cement specifications for each of the following tests on Portland cement: Heat of Hydration
FWHA equation
Describe a gradation chart with the sieve sizes raised to 0.45 power.
1 g/cm^3 =62.4 lbm/ft^3 1psi = 6.898 kPa 1 in-lbf = (0.0254m)(4.45N)
Know the density energy and pressure units
94 lbs.
One commercial sack of Portland cement weighs
3", 1 1/2", 3/4", 3/8", #4, #8, #16, #30, #50, #100 & #200.
Standard sieve sizes
C3A
There are four main chemical compounds that are present in Portland cement. Which compound is responsible for the sulfate attack in concrete?
Slump test Unit weight test
What are two convenient tests to check whether or not a concrete mix has been properly batched?
A siliceous or siliceous and aluminous material which in itself possesses no cementing property but will, in the presence of water, react with calcium hydroxide to form a cementitious product which is stable in water. (ie. volcanic ash (or pumicite) and fly ash)
What is a pozzolan?
The early strength of concrete is reduced
Which one of the following statements is true concerning the effect of using fly ash as a cement replacement in concrete?
Lower permeability reduces corrosion of rebar in concrete
Which one of the following statements is true concerning the effects of permeability of hardened concrete?
Rough textured and angular aggregates give higher strength to the concrete at the same w/c ratio
Which one of the following statements is true concerning the effects particle shape and surface texture of aggregate on the properties of fresh and hardened concrete?
Type IV
Which type of Portland cement would you use in a concrete damn?
Type III
Which type of Portland cement would you use in a concrete if you would like to achieve high early strength?
Joseph Aspdin, an English brick mason, obtained a patent for Portland cement in 1824. (Greeks and Romans used hydraulic cement)
Who invented Portland cement and when? (Joseph Aspdin, an English brick mason, obtained a patent for Portland cement in 1824.)
The concrete it produces resembled the color of the natural limestone in the Isle of Portland.
Why is it called Portland cement?
140 pcf
A typical density of normal non-air-entrained concrete made with Florida limestone is
(A) Normal natural aggregates Bulk unit weight = 95-105pcf (B) Lightweight aggregates Bulk unit weight = < 70pcf (C) Heavyweight aggregate Bulk unit weight = > 130pcf (D) blast-furnace slag Bulk unit weight = 70-85pcf
Compare and know the typical bulk unit weights of (A) normal natural aggregates. (B) lightweight aggregates, (C) heavyweight aggregate and (D) blast-furnace slag.
A: Determine the absorption of the aggregate B: As a percent C: Tells you how much water the aggregate has absorbed and how much more it can absorb
Describe (A) the purpose of the test, (B) how the test results are reported, (C) the meaning of the test results, and (D) the typical threshold test values (if any) required in material specifications, for each of the following tests on aggregates: Absorption and Surface Moisture Test
A:To determine hardness or resistance to abrasion of an aggregate B:As a percentage LA=(change in wt. #12 sieve / original wt. #12 sieve) * 100% C: The higher the percentage, the softer the aggregate. This is bad! We want a low percentage D: FDOT Specs: LA loss should be less than 45%
Describe (A) the purpose of the test, (B) how the test results are reported, (C) the meaning of the test results, and (D) the typical threshold test values (if any) required in material specifications, for each of the following tests on aggregates: L.A. Abrasion Test
A: To determine the percent passing #200 sieve by wet sieving and drying B: As percent passing C: If material has a high percent passing, it is too fine D: Max allowable: 1% for coarse aggregate 3-5% for fine aggregate
Describe (A) the purpose of the test, (B) how the test results are reported, (C) the meaning of the test results, and (D) the typical threshold test values (if any) required in material specifications, for each of the following tests on aggregates: Materials Finer than No. 200 Sieve
A: To determine the potential alkali reactivity of an aggregate B: As a percentage C: If expansion is greater than 0.05% at 3 months or 0.10% in 6 months, the aggregate is considered to be alkali reactive
Describe (A) the purpose of the test, (B) how the test results are reported, (C) the meaning of the test results, and (D) the typical threshold test values (if any) required in material specifications, for each of the following tests on aggregates: Potential Reactivity
A: To determine gradation (size distribution) of aggregates B: As a weight C: The more weight retained in the larger sieves, the more coarse the aggregate. Similarly, the less weight retained the finer it is. D: Fineness Modulus = 2.3-3.1
Describe (A) the purpose of the test, (B) how the test results are reported, (C) the meaning of the test results, and (D) the typical threshold test values (if any) required in material specifications, for each of the following tests on aggregates: Sieve Analysis
A: To measure resistance of an aggregate to weathering through cycles of soaking in sodium or magnesium sulfate and oven drying B: As a percentage % Soundness Test = wt. average of % weight loss after test C: The higher the percentage, the less sound the aggregate. Sound means that the aggregate is weather resistant. D: FDOT Specs: soundness loss < 12% (immerse in sodium sulfate, separate into 4 size fractions)
Describe (A) the purpose of the test, (B) how the test results are reported, (C) the meaning of the test results, and (D) the typical threshold test values (if any) required in material specifications, for each of the following tests on aggregates: Soundness Test
A: To make weight-volume conversions and calculate the void content D: Depends on the aggregate
Describe (A) the purpose of the test, (B) how the test results are reported, (C) the meaning of the test results, and (D) the typical threshold test values (if any) required in material specifications, for each of the following tests on aggregates: Specific Gravity Test
A: To determine the presence of injurious organic compounds in natural sands B: As a percentage (Average strength of mortar with unwashed agg.) / (Average strength of mortar with washed egg) * 100% C: If the color of the liquid is darker than a solution of Potassium Dichromate in Sulfuric Acid, organic purities might be present and further tests (ASTM C87) should be made before the sand can be approved D: The strength ration should be greater than 95%
Describe (A) the purpose of the test, (B) how the test results are reported, (C) the meaning of the test results, and (D) the typical threshold test values (if any) required in material specifications, for each of the following tests on aggregates:-Organic Impurity Test -Effect of Organic Impurity of Fine Aggregate on Strength of Mortar
A: To test for the soundness of cement B: In percentage length change C: The less change in length, the more sound the cement is D: ASTM C150 specification for Portland cement limits the maximum autoclave expansion to 0.8%
Describe (A) the purpose of the test, (B) how the test results are reported, (C) the meaning or significance of the test results, (D) the typical threshold test values (if any) required in cement specifications for each of the following tests on Portland cement: Autoclave Expansion
A: To measure the fineness of a cement B: In specific surface, m^2/kg C: The greater the fineness, the more rapid the rate of hydration D: ASTM C150 specifies a minimum fineness of 280 m2/kg for Type: I, II, IV, and V cements
Describe (A) the purpose of the test, (B) how the test results are reported, (C) the meaning or significance of the test results, (D) the typical threshold test values (if any) required in cement specifications for each of the following tests on Portland cement: Blaine Air Permeability
A: To ensure the quality of a cement with regards to strength development B: In psi or Pa C: To make sure cement has right quality D: Required compressive strengths for Type I cement: 1800psi at 3days and 2800psi at 2days
Describe (A) the purpose of the test, (B) how the test results are reported, (C) the meaning or significance of the test results, (D) the typical threshold test values (if any) required in cement specifications for each of the following tests on Portland cement: Compressive Strength Test on Mortar Cubes
A: To measure the level of pre-hydration of a cement B: In percent weight loss C: A high % loss on ignition gives an indication of high pre-hydration and carbonation D: ASTM C150 limits the max loss on ignition at 3.0% for Types I, II, III, and V; and 2.5% for Type IV Portland cement
Describe (A) the purpose of the test, (B) how the test results are reported, (C) the meaning or significance of the test results, (D) the typical threshold test values (if any) required in cement specifications for each of the following tests on Portland cement: Loss on Ignition
A: To determine the quality of a cement with regards to its rate of setting B: In initial and final setting time in minutes C: Quality D: ASTM C150 specification on time of setting: Min. Initial setting time = 45min Max Final setting time = 375min
Describe (A) the purpose of the test, (B) how the test results are reported, (C) the meaning or significance of the test results, (D) the typical threshold test values (if any) required in cement specifications for each of the following tests on Portland cement: Vicat
A: To measure the fineness of a cement B: In specific surface, m^2/kg C: The greater the fineness, the more rapid the rate of hydration D: ASTM C150 specifies a minimum fineness of 160 m2/kg for Type: I, II, III, IV, and V cements
Describe (A) the purpose of the test, (B) how the test results are reported, (C) the meaning or significance of the test results, (D) the typical threshold test values (if any) required in cement specifications for each of the following tests on Portland cement: Wagner Turbidimeter
Blast -furnace slay, expanded clay, and expanded shale.
Give a few examples of artificial aggregates
intrusive igneous rock
Granite is classified as what type of rock?
Batching by weight gives better uniformity
How do we ensure uniformity in batching for a concrete mix?
Required plan mixing time: 1 to 3 min
How long should we mix a concrete mixture
4.45 lbf =1 N
How many Newtons are equal to on pound force?
2.54cm= 1 in.
How many centimeters are equal to one inch?
45g=1 lbm
How many grams are equal to one pound mass? (lbm.)
#8
If an aggregate has a graduation as given in problem 1 part 1 what is the nominal maximum aggregate size of this aggregate?
(A) The dry bulk specific gravity Bulk Dry Sp. Gr. = A / B+S-C A = Mass of oven-dry sample in air, g B = Mass of Pycnometer filled with water to calibration mark, g C = Mass of Pycnometer with sample and water to calibration mark, g S = Mass of saturated surface dry sample,
Know how to compute for (A) the dry bulk specific gravity
FM: 2.3 - 3.31 Fineness Modulus = Total of % Retained / 100
Know how to compute the Fineness Modulus of a fine aggregate given the results of a sieve analysis. What are highest and lowest possible values of F.M.?
sedimentary rock
Limestone is classified as which one of the following types of rock?
To allow concrete to expand without pushing against the structure
The main purpose of an isolation joint in a concrete structure is:
-Well/Dense Graded: well distributed in various sizes resulting in low air voids and high density when compacted -Uniform Gradation: mostly one size -Gap Grade: missing a few sizes; better than uniform but not good enough
What are (A) a uniform, (B) a gap-graded, and (C) a well-graded or dense-graded gradations? What are the typical plots of these gradations on a gradation chart? Which of these gradations are open-graded?
Fuller's Maximum Density Curve: %P = (d / D) ^0.5 x 100% Where: %P = % Passing the sieve d = Size of the sieve D = Maximum aggregate size FHWA Maximum Density Curve: (this equation works better) %P = (d / D) ^0.45 x 100
What are the Fuller's Maximum Density Curve and the FHWA's Maximum Density Curve?
Length- meters (m)- feet (ft) Mass- grams(g)- pounds (lb) Force- Newtons (N) - pound force (lbf) Pressure- Pascal(Pa or N/m2) - pound / inch2 (psi) Energy- Joule(J) - foot pound force (ft lbf)
What are the SI units for length, mass, force, pressure and energy and their symbols? What are their American units
Tensile strength is 10% of the compressive strength. Flexural strength is 15-20% of compressive strength. Elastic modulus is 57000*sq.rt. of fc
What are the approximate relationships between the tensile strength, flexural strength and elastic modulus with the compressive strength of concrete?
-Coarse Aggregate - particles retained on #4 sieve (gravel) -Fine Aggregate - particles passing #4 sieve (sand)
What are the definitions of coarse and fine aggregates?
Ease of transport and placement, resistance to bleeding and segregation, consistency, cohesiveness, and workability
What are the desirable properties of a fresh concrete?
Rough textured and angular aggregates give better bonding between the aggregate and the cement and thus higher strength. Sieve analysis, LA abrasion loss, and soundness loss tests.
What are the desirable properties of aggregate for use in Portland cement concrete? What tests would you run on the aggregate to ensure that an aggregate has these desirable properties?
Bulk Density: mass of aggregate / Volume solids + voids Bulk Unit Weight: weight of aggregate / bulk volume of aggregate (volume of container)
What are the difference between the bulk density and the bulk unit weight of an aggregate?
Lower early strength & lower heat of hydration as compared with normal concrete. Ultimate strength can be higher than that of normal concrete. Portland blast-furnace slag cement has a more rapid strength gain than Portland pozzolan cement.
What are the differences in properties of a Portland-blast-furnace-slag cement as compared with those of a normal Portland cement concrete?
Different ways concrete can be mixed: central mixed concrete, shrink mixed concrete, and truck mixed. Different ways concrete can be transported: bucket, buggy, belt conveyor, pump, chute, and shotcrete. Different kinds of trucks used: mixer truck and special dump truck
What are the different ways concrete can be batched, mixed and transported to the job site? What are the different kinds of truck used to transport concrete to the job site?
Permeability is the ease of flow of fluid or gas through the concrete. Low permeability is needed to prevent: a. Disintegration caused by freezing of saturated porous concrete b. Dissolving of slowly soluble components in concrete c. Chloride intrusion causes corrosion of rebars
What are the effects of concrete permeability on its performance?
Water resistance is increased since calcium hydroxide is consumed. Permeability is reduced since more pores are filled by the products of pozzolanic reaction. Since the rate of sulfate attack depends on the permeability and the amount of calcium hydroxide, the sulfate resistance of the concrete is increased (with the reduction in permeability and calcium hydroxide.) Type IS cement containing 60 to 70% slag is highly resistant to sulfate attack irrespective of C3A content of the Portland cement and the reactive alumina content of the slag. Alkali-aggregate expansion is reduced.
What are the effects of pozzolan and ground granulated blast furnace slag on the strength and durability of concrete?
1. Type I - For general use. No limits are placed on any of the four principal compounds. 2. Type II - moderate sulfate resistance and moderate heat of hydration. Specification limits the C3A content to a maximum of 8%. 3. Type III - high early strength. C3A content is limited to a maximum of 15%. 4. Type IV - low hear of hydration. Maximum limits of 35% and 7% on C3S and C3A, respectively. Minimum of 40% C2S 5. Type V - high sulfate resistance. Maximum limit of 5% on C3A Type IA, IIA, IIIA - Air-entraining.
What are the five main types of Portland cement and their applications?
Limestone, sand, and clay. 1. Quarrying and blending of raw materials 2. Proportioning and fine grinding of raw materials 3. Kilm system: preheating, burning, cooling, and clinker storage 4. Finish grinding and shipping
What are the main raw materials used in the manufacturing of Portland cement? Describe the basic steps in the manufacturing of Portland cement.
Tricalcium Silicate, Dicalcium Silicate, Tricalcium Aluminate, and Tetracalcium Aluminoferrit
What are the three main ingredients in Portland cement concrete?
1. Igneous Rock: formed on cooling of the magma -Intrusive Igneous - slow cooling beneath earth's surface [granite, trap rock] -Extrusive Igneous - rapid cooling at or near earth's surface [basalt, perlite] 2. Sedimentary Rock - formed by disintegration of other rocks and deposited as sediments [limestone, sandstone, shale] 3. Metamorphic Rock - igneous or sedimentary rock that changed structure due to heat and pressure (usually harder and denser) [marble, slate]
What are the three major types of rock and how were they formed? What are the differences between intrusive igneous and extrusive igneous rocks? Give an example for each type of rock
Slump test and ball penetration test
What are the two commonly-used methods to measure the consistency of a fresh concrete?
A) Large foundations: 0.5-2.5in (B) Pavements: 2-5.5in (C) Columns: 5-8in
What are the typical specified slump of fresh concrete for (A) large foundations, (B) pavements, and (C) columns?
Portland pozzolan cement (Type IP & P) - blend of Portland cement with 15 to 40% fine pozzolan by weight. Type P has a lower early strength than Type IP, and is used when high early strength is not required. Differences: Lower early strength & lower heat of hydration as compared with normal concrete. Ultimate strength can be higher than that of normal concrete
What is a Portland-pozzolan cement? What are the differences in properties between a Portland-pozzolan cement concrete and a normal Portland cement concrete?
Pozzolan + CH + H ⇒ C-S-H (1) Reaction is Slow. (2) It consumes calcium hydroxide instead of producing it. (3) The large capillary spaces are filled up by the reaction products, making the concrete less permeable and more durable
What is a pozzolanic reaction?
Normal concrete: ≈ 2.4 Mg/m3 (150 pcf) Concrete made with Florida limestone: ≈ 2.24 Mg/m3 (140 pcf)
What is a typical density of normal concrete? What is the typical density of concrete made with Florida limestone?
Bleeding of fresh concrete is manifested by the appearance of water on the surface after a concrete has been placed and compacted. 1.Use air-entrainment and reduce water content 2.Increase the proportion of sand/cement in the concrete mix 3.Use mineral add mixtures such as fly ash or ground blast-furnace slag and reduce water content
What is bleeding in fresh concrete? What are the effective remedies to reduce bleeding problems?
It is the continued yielding under sustained stress, its important because it may cause reduction of pre-stress in pre-stressed concrete structures.
What is creep property, and why is it important to evaluate the creep property of concrete?
Maximum: the smallest sieve that 100% of the aggregates must pass. Nominal: the smallest sieve which the major portion of the aggregate must pass (85-95% pass through)
What is the (A) maximum aggregate size, and (B) nominal maximum aggregate size?
Tensile strength is about 1/10 of compressive strength
What is the approximate relationship between the tensile strength and and the compressive strength of concrete?
White Cement: Used to produce architectural concrete where white color is desired, this is achieved by reducing the iron content of the cement. Similar to normal Portland cement in properties. Colored Cements: Produced by (1) adding pigments to white cement, or (2) using clinkers having the corresponding colors. Similar to normal Portland cement in properties.
What is the main difference between a white Portland cement, a colored Portland cement and a normal Portland cement?
Maximum size = 75µm, finer than #200 sieve.
What is the maximum size of Portland cement particles?
Water to cement ratio
What is the most important factor affecting strength of a hardened concrete?
Water content: is the most important factor because the higher the water content, the higher the slump. Cement content: lowering the cement content tends to produce a harsher mixture which is harder to finish, and increasing it tends to give better cohesiveness but higher stickiness. Aggregate size: increasing the maximum aggregate size increases the slump. Aggregate angularity and roughness: higher angularity and roughness produce fresh concrete with lower slump. Add mixture: water reducing, air-entraining and fly ash admixtures increase the slump.
What is the most important factor affecting the consistency of a fresh concrete? What are the other factors affecting the consistency of a fresh concrete? Describe these factors and their effects
a) Water Cement Ratio: Lower water/cement = higher strength b) Age (or curing time) Strength generally increases with curing time c) Curing Condition Longer moist curing & higher temperature = higher strength d) Type of cement & admixture Can affect rate of strength gain & ultimate strength e) Strength of aggregate Strength of concrete is limited by the strength of aggregate f) Moisture Content of Concrete higher moisture = lower strength
What is the most important mix parameter affecting the strength of concrete? What are the other factors affecting the strength? Describe these factors and their effects
They both measure the consistency of fresh concrete.
What is the relationship between the results obtained by these two methods?
15 to 40 mpa or 2000 to 6000 psi
What is the typical range of 28-day compressive strength of normal concrete?
3.15
What is the typical specific gravity of Portland cement?
Specific Gravity = 3.15
What is the typical specific gravity of Portland cement?
1bag of commercial Portland cement = 94lbs You want 6bag of 94lbs/ft3 of Portland cement.
What is weight of a commercial sack of Portland cement? What does a six-bag mix mean?
Lower permeability reduces damage by freezing water in concrete
Which of the following is true concerning the effect of permeability of hardened concrete?
Strike off, bull floating, floating, troweling
Which one of the following is a correct sequence of steps in finishing a concrete slab?
Spray concrete with icy water
Which one of the following is not an effective measure to be taken in hot-weather concreting.
Use air entrainment and reduce water content in concrete
Which one of the following measures is effective in reducing bleeding in concrete?
SSD Bulk Density
Which one of the following properties of the same aggregate would have the highest value
Dry bulk unit weight
Which one of the following properties of the same aggregate would have the lowest value?
It is always more cost effective to use rough textured and angular aggregates as compared with round and smooth aggregates in concrete
Which one of the following statements is not true concerning the effects of particle shape and surface texture of aggregate on the properties of fresh and hardened concrete?