Construction Materials and Lab Final
Questions with Correct Answers
ASTM - ANSWERSAmerican Society for Testing and Materials
AASHTO - ANSWERSAmerican Association of State Highway and Transportation
Officials
Typical Cylinder Standards - ANSWERS6 x 12 Cylinders** ,4 x 8 Cylinders.
Coarse Aggregate - ANSWERSRetained on a sieve with 4.75mm openings
Fine Aggregate - ANSWERSPassing a sieve with 4.75 mm openings
Negative Free Moisture - ANSWERSAggregates will absorb water
Positive Free Moisture - ANSWERSAggregates will release water
Specific Gravity - ANSWERSThe mass of a material divided by the mass of water
whose volume is equal to the volume of the material at a specific temperature
High Density Gradation ( Well Graded) - ANSWERShas a good mix of all particle sizes
which means the aggregates use most of the volume and less cement or asphalt is
needed
One-size gradation (Uniform) - ANSWERSall same size = nearly vertical curve
Gap-Graded - ANSWERSmissing some sizes = nearly horizontal section of curve
Open-Graded - ANSWERS-missing small aggregates which fill in holes between larger
ones
-lower part of curve is skewed toward large sizes
Fineness Modulus - ANSWERS-Measure of the particle-size distribution of fine
aggregate
-Only #100, 50, 30, 16, 8, 4, and 3/8" sieves are used
Absorption - ANSWERSThe moisture content of an aggregate that is in the SSD
condition
ASTM C33 fineness modulus of fine aggregate in concrete should fall within this range -
ANSWERS2.3 - 3.1
,If Fly Ash is used to replace some of the cement in a concrete you could expect it to? -
ANSWERSLead to a slower strength gain
Adding a water reducer without altering the other quantities of the ingredients in a
concrete mix will? - ANSWERSIncrease the slump of the mix
At Cool temperatures, concrete will... - ANSWERSHydrate slower than if temperatures
were high
Cement Paste - ANSWERSPortland Cement + Water
Mortar - ANSWERSPortland Cement Paste + Sand
Concrete - ANSWERSCement + Water + Sand + Aggregates + Admixtures
Main Components of Cement - ANSWERStricalcium silicate (C3S) , dicalcium silicate
(C2S) , tricalcium aluminate (C3A) , tetracalcium aluminoferrite (C4AF)
Specific Gravity of Cement - ANSWERS3.15
What is produced from the hydration of C3S & C2S? - ANSWERSC-S-H (Calcim-
silicate-hydrate)
During Hydration, what is C3S good for? - ANSWERSEarly Strength Gain
During Hydration, What is C2S good for? - ANSWERSLater Strength Gain
What are the Stages of Hydration? - ANSWERSInitial, Dormancy, Precipitation of
Hydrates ( Acceleration period into crystallization)
Voids in Hydrated Cement - ANSWERSinterlayer hydration space, capillary voids,
trapped voids, entrained air
Stiffening - ANSWERSchange from plastic to solid (initial and final)
-not the same as hardening, which is strength gain
-handling, placing, & vibrating must be completed before initial set
-finishing between initial and final
-curing after final set
False Set - ANSWERSpremature stiffening within a few minutes
-due to humidity in cement during storage
-remix without adding water
Quick set and Flash set - ANSWERS-cannot be fixed
-occurs quickly 10-45 minutes
, -due to imbalance of aluminates and sulfates( this is why gypsum is added)
water-cement ratio - ANSWERSthe ratio of water to cement in a concrete mix, which is
the main factor which determines concrete strength
-water need for hydration, w/c=0.22 - 0.25 but typically use > 0.40
Effect of more water in water-cement ratio? - ANSWERS-Decreases Strength
-Decreases Durability
-Decreases bond between successive layers
-Decreases bond between concrete and rebar
-Increases Permeability
-More workability but causes voids
Standard Types of Cement - ANSWERSI Normal
II Moderate Sulfate Resistance
III High Early Strength
IV Low Heat of Hydration
V High Sulfate Resistance
Admixtures for Concrete - ANSWERSCommonly used to improve properties of fresh
and hardened concrete
Types of Admixtures for Concrete - ANSWERS1. Air Entrainer
2. Water Reducer
3. Retarder
4. Hydration Controller
5. Accelerator
6. Specialty Admixtures
Air Entrainers - ANSWERS-produce tiny air bubbles in hardened concrete to provide
space for water to expand upon freezing
-Improve workability, resistance to de-icing chemicals, sulfates, & alkalis
-Decreases strength but this can be compensated with lower w/c ratio
Entrapped Air - ANSWERSHarmful Air bubbles in concrete that have been entrapped
during the mixing process. 1% - 3%.
Water Reducers - ANSWERSIncrease mobility of cement particles.
Improves workability - measured with slump test
Increase strength using lower w/c ratio
Types of Water Reducers - ANSWERSStandard, Mid-Range, High-Range
( Superplasticizers)
Retarders - ANSWERS-Slows down the initial setting of a concrete mix in order to allow
more time for placing and working the mix
Questions with Correct Answers
ASTM - ANSWERSAmerican Society for Testing and Materials
AASHTO - ANSWERSAmerican Association of State Highway and Transportation
Officials
Typical Cylinder Standards - ANSWERS6 x 12 Cylinders** ,4 x 8 Cylinders.
Coarse Aggregate - ANSWERSRetained on a sieve with 4.75mm openings
Fine Aggregate - ANSWERSPassing a sieve with 4.75 mm openings
Negative Free Moisture - ANSWERSAggregates will absorb water
Positive Free Moisture - ANSWERSAggregates will release water
Specific Gravity - ANSWERSThe mass of a material divided by the mass of water
whose volume is equal to the volume of the material at a specific temperature
High Density Gradation ( Well Graded) - ANSWERShas a good mix of all particle sizes
which means the aggregates use most of the volume and less cement or asphalt is
needed
One-size gradation (Uniform) - ANSWERSall same size = nearly vertical curve
Gap-Graded - ANSWERSmissing some sizes = nearly horizontal section of curve
Open-Graded - ANSWERS-missing small aggregates which fill in holes between larger
ones
-lower part of curve is skewed toward large sizes
Fineness Modulus - ANSWERS-Measure of the particle-size distribution of fine
aggregate
-Only #100, 50, 30, 16, 8, 4, and 3/8" sieves are used
Absorption - ANSWERSThe moisture content of an aggregate that is in the SSD
condition
ASTM C33 fineness modulus of fine aggregate in concrete should fall within this range -
ANSWERS2.3 - 3.1
,If Fly Ash is used to replace some of the cement in a concrete you could expect it to? -
ANSWERSLead to a slower strength gain
Adding a water reducer without altering the other quantities of the ingredients in a
concrete mix will? - ANSWERSIncrease the slump of the mix
At Cool temperatures, concrete will... - ANSWERSHydrate slower than if temperatures
were high
Cement Paste - ANSWERSPortland Cement + Water
Mortar - ANSWERSPortland Cement Paste + Sand
Concrete - ANSWERSCement + Water + Sand + Aggregates + Admixtures
Main Components of Cement - ANSWERStricalcium silicate (C3S) , dicalcium silicate
(C2S) , tricalcium aluminate (C3A) , tetracalcium aluminoferrite (C4AF)
Specific Gravity of Cement - ANSWERS3.15
What is produced from the hydration of C3S & C2S? - ANSWERSC-S-H (Calcim-
silicate-hydrate)
During Hydration, what is C3S good for? - ANSWERSEarly Strength Gain
During Hydration, What is C2S good for? - ANSWERSLater Strength Gain
What are the Stages of Hydration? - ANSWERSInitial, Dormancy, Precipitation of
Hydrates ( Acceleration period into crystallization)
Voids in Hydrated Cement - ANSWERSinterlayer hydration space, capillary voids,
trapped voids, entrained air
Stiffening - ANSWERSchange from plastic to solid (initial and final)
-not the same as hardening, which is strength gain
-handling, placing, & vibrating must be completed before initial set
-finishing between initial and final
-curing after final set
False Set - ANSWERSpremature stiffening within a few minutes
-due to humidity in cement during storage
-remix without adding water
Quick set and Flash set - ANSWERS-cannot be fixed
-occurs quickly 10-45 minutes
, -due to imbalance of aluminates and sulfates( this is why gypsum is added)
water-cement ratio - ANSWERSthe ratio of water to cement in a concrete mix, which is
the main factor which determines concrete strength
-water need for hydration, w/c=0.22 - 0.25 but typically use > 0.40
Effect of more water in water-cement ratio? - ANSWERS-Decreases Strength
-Decreases Durability
-Decreases bond between successive layers
-Decreases bond between concrete and rebar
-Increases Permeability
-More workability but causes voids
Standard Types of Cement - ANSWERSI Normal
II Moderate Sulfate Resistance
III High Early Strength
IV Low Heat of Hydration
V High Sulfate Resistance
Admixtures for Concrete - ANSWERSCommonly used to improve properties of fresh
and hardened concrete
Types of Admixtures for Concrete - ANSWERS1. Air Entrainer
2. Water Reducer
3. Retarder
4. Hydration Controller
5. Accelerator
6. Specialty Admixtures
Air Entrainers - ANSWERS-produce tiny air bubbles in hardened concrete to provide
space for water to expand upon freezing
-Improve workability, resistance to de-icing chemicals, sulfates, & alkalis
-Decreases strength but this can be compensated with lower w/c ratio
Entrapped Air - ANSWERSHarmful Air bubbles in concrete that have been entrapped
during the mixing process. 1% - 3%.
Water Reducers - ANSWERSIncrease mobility of cement particles.
Improves workability - measured with slump test
Increase strength using lower w/c ratio
Types of Water Reducers - ANSWERSStandard, Mid-Range, High-Range
( Superplasticizers)
Retarders - ANSWERS-Slows down the initial setting of a concrete mix in order to allow
more time for placing and working the mix
