CIVL 215 Final Exam Review UPDATED
ACTUAL QUESTIONS AND CORRECT
ANSWERS
Stress vs strength - CORRECT ANSWER internal resistance in material vs. Maximum stress a
material can withstand
Yield stress/strength - CORRECT ANSWER maximum stress a material can withstand before
plastic deformation
0.2% offset method - CORRECT ANSWER 0.002 over on the x-axis, parallel to linear portion
of stress/strain curve until crossing stress/strain curve
0.5% extension method - CORRECT ANSWER 0.005 over on the x-axis, straight up until
crossing stress/strain curve
Elastic zone - CORRECT ANSWER load removed, goes back to original shape
Plastic zone - CORRECT ANSWER load removed, does not go back to original shape and
plastically deformed
True stress/strain - CORRECT ANSWER calculated with tested/stretched gauge legnth
Engineering stress - CORRECT ANSWER calculated using unstretched gauge length, more
common reported values
1. Perfectly elastic
2. Elastic and perfectly plastic
3. Elastoplastic and strain hardening - CORRECT ANSWER 1. No plastic behavior, no warning
before failure (brittle)
2. Once yield is reached, deforms plastically at same stress level
3. Ductile materials when plastically deformed
,Toughness - CORRECT ANSWER - a materials ability to absorb energy before fracture
(measured by Charpy impact test which imposed dynamic loading)
- calculated as the area under the stress-strain curve up to fracture
Poisson's ratio - CORRECT ANSWER ratio of lateral to axial strain in tensile deformation
Transition temperature - CORRECT ANSWER behavior changes from ductile to brittle when
temperature drops below a threshold
Creep - CORRECT ANSWER - increase in strain at a constant stress
- slowed down by rebar
Stress relaxation - CORRECT ANSWER decrease in stresses at constant strain
Fatigue - CORRECT ANSWER repeated cycles of loading and unloading reduce the strenght of
material over time (ex. Cracked pavement)
Order of operations of concrete - CORRECT ANSWER mix design, mixing of concrete,
transporting, pouring, vibrating (initial set), finishing (final set), curing, maintenance
Why use aggregates? - CORRECT ANSWER cost, dimensional stability, better durability,
strength
Aggregate sources - CORRECT ANSWER - natural aggregates (sand and gravel, crushed stone,
smooth rocks worn down by water)
- manufactured aggregates (steel slag, crushed waste, manufactured sand)
Aggregate size - CORRECT ANSWER - fine (passes through no. 4 sieve (4.75mm))
- coarse (retained in no. 4 sieve)
, NMAS (nominal max. Aggregate size) - CORRECT ANSWER smallest sieve through which
majority of aggregate sample passes
Formwork - 1/5 of smallest dimension
Rebar - 3/4 of spacing between reinforcement
Slab - 1/3 of slab thickness
Gradation of aggregate - CORRECT ANSWER single size - poor strength, not recommended
Gap graded - intermediate sizes omitted
Well graded - good strength and workability
Fineness modulus - CORRECT ANSWER higher the FM, the coarser the aggregate
To calculate: sum of cumulative % retained, divided by 100
Grading limits (plot) - CORRECT ANSWER plot of sieve size (x) vs. Percent passing (y) on a
log scale
Fine aggregates must stay within first curve
Coarse aggregates must stay within second curve
Levels of moisture absorption - CORRECT ANSWER oven dry - all moisture removed
Air dry - surface pores are partially full of moisture
SSD - surface pores full, dry surface
Wet - surface pores full, free moisture on surface
Particle shape - CORRECT ANSWER angular and rough - required more water to place
concrete, less workability, use for base course and asphalt
Round and smooth - requires less water, more workability, use for portland cement
Concrete mixture characteristics based on: - CORRECT ANSWER - intended concrete use
- exposure conditions
- size and shape of formwork
ACTUAL QUESTIONS AND CORRECT
ANSWERS
Stress vs strength - CORRECT ANSWER internal resistance in material vs. Maximum stress a
material can withstand
Yield stress/strength - CORRECT ANSWER maximum stress a material can withstand before
plastic deformation
0.2% offset method - CORRECT ANSWER 0.002 over on the x-axis, parallel to linear portion
of stress/strain curve until crossing stress/strain curve
0.5% extension method - CORRECT ANSWER 0.005 over on the x-axis, straight up until
crossing stress/strain curve
Elastic zone - CORRECT ANSWER load removed, goes back to original shape
Plastic zone - CORRECT ANSWER load removed, does not go back to original shape and
plastically deformed
True stress/strain - CORRECT ANSWER calculated with tested/stretched gauge legnth
Engineering stress - CORRECT ANSWER calculated using unstretched gauge length, more
common reported values
1. Perfectly elastic
2. Elastic and perfectly plastic
3. Elastoplastic and strain hardening - CORRECT ANSWER 1. No plastic behavior, no warning
before failure (brittle)
2. Once yield is reached, deforms plastically at same stress level
3. Ductile materials when plastically deformed
,Toughness - CORRECT ANSWER - a materials ability to absorb energy before fracture
(measured by Charpy impact test which imposed dynamic loading)
- calculated as the area under the stress-strain curve up to fracture
Poisson's ratio - CORRECT ANSWER ratio of lateral to axial strain in tensile deformation
Transition temperature - CORRECT ANSWER behavior changes from ductile to brittle when
temperature drops below a threshold
Creep - CORRECT ANSWER - increase in strain at a constant stress
- slowed down by rebar
Stress relaxation - CORRECT ANSWER decrease in stresses at constant strain
Fatigue - CORRECT ANSWER repeated cycles of loading and unloading reduce the strenght of
material over time (ex. Cracked pavement)
Order of operations of concrete - CORRECT ANSWER mix design, mixing of concrete,
transporting, pouring, vibrating (initial set), finishing (final set), curing, maintenance
Why use aggregates? - CORRECT ANSWER cost, dimensional stability, better durability,
strength
Aggregate sources - CORRECT ANSWER - natural aggregates (sand and gravel, crushed stone,
smooth rocks worn down by water)
- manufactured aggregates (steel slag, crushed waste, manufactured sand)
Aggregate size - CORRECT ANSWER - fine (passes through no. 4 sieve (4.75mm))
- coarse (retained in no. 4 sieve)
, NMAS (nominal max. Aggregate size) - CORRECT ANSWER smallest sieve through which
majority of aggregate sample passes
Formwork - 1/5 of smallest dimension
Rebar - 3/4 of spacing between reinforcement
Slab - 1/3 of slab thickness
Gradation of aggregate - CORRECT ANSWER single size - poor strength, not recommended
Gap graded - intermediate sizes omitted
Well graded - good strength and workability
Fineness modulus - CORRECT ANSWER higher the FM, the coarser the aggregate
To calculate: sum of cumulative % retained, divided by 100
Grading limits (plot) - CORRECT ANSWER plot of sieve size (x) vs. Percent passing (y) on a
log scale
Fine aggregates must stay within first curve
Coarse aggregates must stay within second curve
Levels of moisture absorption - CORRECT ANSWER oven dry - all moisture removed
Air dry - surface pores are partially full of moisture
SSD - surface pores full, dry surface
Wet - surface pores full, free moisture on surface
Particle shape - CORRECT ANSWER angular and rough - required more water to place
concrete, less workability, use for base course and asphalt
Round and smooth - requires less water, more workability, use for portland cement
Concrete mixture characteristics based on: - CORRECT ANSWER - intended concrete use
- exposure conditions
- size and shape of formwork
