CMT Final Exam with all Correct & 100% Verified Answers
|Actual Complete Update |Already Graded A+
Basic Requirements for Placing Concrete ✔Correct Answer-Perserve Concrete Quality
- Water-cement ratio
- Slump
- Air-content
- Homogeneity
Avoid Separation of aggregate and mortar
Avoid Excess horizontal movement
Consolidate adequately
Preparation before placing includes ✔Correct Answer-- Trimming
- Moistening
- Compacting
Depositing Concrete ✔Correct Answer-DO NOT
- disturb saturated subgrades so bearing capacity is maintained
- deposit on frozen subgrade
Deposit continuously and as near as possible to its final position
Rate of placement should be such that previously placed concrete has not set when the next
layer is placed upon it
Slab Construction ✔Correct Answer-start placing along perimeter at one end with each batch
discharged against previously placed concrete
DO NOT
- dump in sperate piles & then level and work together
- deposit in large piles & then move horizontally into position
These practices result in segregation (mortar flows ahead of coarser material)
Effective Use of Wheelbarrows ✔Correct Answer-Discharging into previously placed concrete
Pavement Slab ✔Correct Answer-Concrete deposited in front of slipform paver by dump
trucks
Concrete spread evenly across the sub grade by the paver before consolidation and finishing
Paving Train ✔Correct Answer-- Cure Machine
- Tine Machine
- Paver
- Spreader 2
- Spreader 1
, Underwater Placement Methods ✔Correct Answer-Tremie
Advantages: can be used to funnel concrete down through the water into the structure
Watch For: Discharge end always has to be buried in fresh concrete to ensure seal between
water & concrete mass
Consolidating Concrete ✔Correct Answer-Internal Vibration
External Vibration
- Form vibrators
- Vibratory tables
- Surface vibrators
- Plate vibrators
- Vibratory screeds
- Vibratory roller screeds
Inadequate Consolidation can result in ✔Correct Answer-- Honeycomb
- Sand Streaks
- Cold Joints
- Placement Lines
Nuclear Gauges ✔Correct Answer-Determines subbase compaction
Bonding New to Previously Hardened Concrete ✔Correct Answer-Latex
Epoxy
Curing requires adequate ✔Correct Answer-moisture
temperature
time
(if any of these factors are neglected, then desired properties will not develop)
Effect of adequate curing on hardened concrete ✔Correct Answer-Increased:
strength
watertightness
abrasion resistance
Curing methods ✔Correct Answer-1). Supply additional water:
- ponding or immersion
- spraying or fogging
- saturated wet coverings
2). Seal in mixing water:
- impervious paper
- plastic sheets
- membrane - furming curing compunds
3). Strength gain is accelerated with:
- Live stream
|Actual Complete Update |Already Graded A+
Basic Requirements for Placing Concrete ✔Correct Answer-Perserve Concrete Quality
- Water-cement ratio
- Slump
- Air-content
- Homogeneity
Avoid Separation of aggregate and mortar
Avoid Excess horizontal movement
Consolidate adequately
Preparation before placing includes ✔Correct Answer-- Trimming
- Moistening
- Compacting
Depositing Concrete ✔Correct Answer-DO NOT
- disturb saturated subgrades so bearing capacity is maintained
- deposit on frozen subgrade
Deposit continuously and as near as possible to its final position
Rate of placement should be such that previously placed concrete has not set when the next
layer is placed upon it
Slab Construction ✔Correct Answer-start placing along perimeter at one end with each batch
discharged against previously placed concrete
DO NOT
- dump in sperate piles & then level and work together
- deposit in large piles & then move horizontally into position
These practices result in segregation (mortar flows ahead of coarser material)
Effective Use of Wheelbarrows ✔Correct Answer-Discharging into previously placed concrete
Pavement Slab ✔Correct Answer-Concrete deposited in front of slipform paver by dump
trucks
Concrete spread evenly across the sub grade by the paver before consolidation and finishing
Paving Train ✔Correct Answer-- Cure Machine
- Tine Machine
- Paver
- Spreader 2
- Spreader 1
, Underwater Placement Methods ✔Correct Answer-Tremie
Advantages: can be used to funnel concrete down through the water into the structure
Watch For: Discharge end always has to be buried in fresh concrete to ensure seal between
water & concrete mass
Consolidating Concrete ✔Correct Answer-Internal Vibration
External Vibration
- Form vibrators
- Vibratory tables
- Surface vibrators
- Plate vibrators
- Vibratory screeds
- Vibratory roller screeds
Inadequate Consolidation can result in ✔Correct Answer-- Honeycomb
- Sand Streaks
- Cold Joints
- Placement Lines
Nuclear Gauges ✔Correct Answer-Determines subbase compaction
Bonding New to Previously Hardened Concrete ✔Correct Answer-Latex
Epoxy
Curing requires adequate ✔Correct Answer-moisture
temperature
time
(if any of these factors are neglected, then desired properties will not develop)
Effect of adequate curing on hardened concrete ✔Correct Answer-Increased:
strength
watertightness
abrasion resistance
Curing methods ✔Correct Answer-1). Supply additional water:
- ponding or immersion
- spraying or fogging
- saturated wet coverings
2). Seal in mixing water:
- impervious paper
- plastic sheets
- membrane - furming curing compunds
3). Strength gain is accelerated with:
- Live stream
