3.1u Concrete Questions by NDTprep.com Flashcards
Concrete Questions (11 cards)
What do we call the underside of a concrete beam in structural terminology?
a. the underside
b. the bottom
c. the invert
d. the soffit
d. the soffit
Explanation: The “soffit” refers to the underside of concrete elements such as slabs or beams. It’s a critical inspection area for spotting cracks or water damage.
Which natural protective process within concrete helps prevent corrosion of steel reinforcement?
a. anodic protection
b. paint application
c. cathodic protection
d. Passivation
d. Passivation
Explanation: Concrete has a high pH (12–13), creating an alkaline environment that forms a passive layer on the steel, protecting it from corrosion.
In pre-stressed concrete, what term refers to the location where a tendon is secured?
a. cachetage point
b. anchor point
c. duct end
d. tremie socket
a. cachetage point
Explanation: A cachetage point is where a pre-stressing tendon is anchored. This is a key component in pre-stressed concrete design.
Which type of concrete flaw involves air voids caused by inadequate compaction?
a. construction joint
b. Honeycombing
c. water jet mark
d. cast-in insert
b. Honeycombing
Explanation: Honeycombing results from inadequate vibration or compaction, leaving air pockets visible on the surface.
What structural role do ducts play in a pre- or post-tensioned concrete beam?
a. They serve as drainage paths
b. They contain rebar
c. They house the tendons
d. They act as injection points
c. They house the tendons
Explanation: Ducts are hollow pathways within concrete used to house tensioning tendons before being grouted.
What function does a jarlan hole serve in a concrete breakwater?
a. underwater cable routing
b. wave energy dissipation
c. Drainage
d. inspection access
b. wave energy dissipation
Explanation: Jarlan holes are found in breakwaters; they reduce wave pressure by allowing controlled water flow.
Which feature in concrete may appear as an irregularity and is typically considered a blemish?
a. construction joint
b. Honeycombing
c. cast in socket
d. water jet damage
a. construction joint
Explanation: A construction joint is a planned discontinuity in the concrete pour but may appear visually irregular or mismatched, hence classified as a blemish during visual inspection.
What chemical condition in concrete inhibits rusting of embedded steel?
a. Coarse aggregates
b. Plasticizers
c. Carbonation
d. High pH environment
d. High pH environment
Explanation: A high-pH environment (12–13) helps steel form a protective oxide layer, reducing rust risk.
In post-tensioned concrete, where is the force from the tendon typically transferred?
a. cachetage point
b. beam edge
c. duct port
d. tendon outlet
a. cachetage point
Explanation: the cachetage point is where the tendon force is transferred to the concrete.
Which of these would be identified as a surface imperfection in underwater concrete?
a. cast-in insert
b. honeycombing
c. planned construction joint
d. tremie tube groove
b. honeycombing
Explanation: Honeycombing disrupts the concrete surface’s integrity and is treated as a blemish in inspection reports.
According to inspection standards, how many primary types of concrete defects are typically noted?
a. 4
b. 2
c. 6
d. 8
d. 8
Explanation: The eight primary types of concrete defects typically recognized during inspection are: Cracks, Voids, Honeycombing, Surface blemishes (e.g., construction joints, discoloration), Delamination, Rebar exposure, Spalling, Blowholes
