Concrete Testing Flashcards
7 cards from real NETTCP practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Concrete Testing flashcards as text
According to AASHTO T 23, how long must freshly molded concrete cylinders remain undisturbed in their molds after casting?
Answer: 16 to 32 hours
AASHTO T 23 requires cylinders to remain undisturbed in molds for 16 to 32 hours before initial curing.
When performing the unit weight test on fresh concrete per AASHTO T 121, what is the correct procedure after filling the measure?
Answer: Strike off the top and weigh the measure
After filling and consolidating, the top surface must be struck off level before weighing the measure.
Which condition would cause a concrete compressive strength test result to be considered invalid?
Answer: Cylinder end is not within 0.5 degrees of perpendicular
If cylinder ends are not within 0.5 degrees of perpendicular, the result may be unreliable and end preparation is required.
What does the term 'w/cm ratio' refer to in concrete mix design?
Answer: Water to cementitious material ratio by weight
The w/cm ratio is the ratio of the mass of water to the mass of all cementitious materials in the mix.
During the modified Proctor compaction test of soils under a concrete slab, how many layers are compacted?
Answer: 5 layers
The modified Proctor test (AASHTO T 180) uses 5 layers compacted with 25 blows each.
What is the maximum aggregate size typically allowed in a standard 4-inch diameter concrete test cylinder?
Answer: 1-1/3 inches
The maximum aggregate size should not exceed one-third of the cylinder diameter; for a 4-inch cylinder that is 1-1/3 inches.
In a bleeding test for fresh concrete (AASHTO T 158), water that accumulates on the surface is collected at what intervals?
Answer: Every 10 minutes for 60 minutes then every 30 minutes
AASHTO T 158 requires collecting bleed water every 10 minutes for the first 60 minutes, then every 30 minutes until bleeding stops.