WACEL -Concrete 1 Technician Exam
Questions with Guaranteed Pass
Solutions.
What are the four basic ingredients of concrete? - Answer Cement, water, coarse aggregate,
and fine aggregate
What indicators are used to evaluate the quality of freshly mixed or hardened concrete with an
emphasis on compressive strength (think field tests)? - Answer Slump, Temperature, Air
Entrained
What is hydration? - Answer A complex chemical process that produces heat and accounts
for the majority of the strength gain of concrete.
What are negative effects of a high w/c ratio? - Answer Cracking, shrinkage, strength
reduction
Should you sample the concrete before or after job-site water is added? - Answer After
What is the max expected value of the air content in non-air entrained concrete? - Answer
2%
What are the effects of air entrainment? - Answer Increased workability and freeze-thaw
resistance, decreased bleeding and compressive strength
What are the two most important details on the concrete batch ticket? - Answer Mix
designations and batch time
What are the time and rotation limitations on batch-to-placement? - Answer 90 minutes,
300 rotations
Should you accept or reject a batch with an unapproved mix designation? - Answer Reject
How do you properly obtain a composite sample from a truck? - Answer Mix two samples
together ideally taken from the middle 1/3 of the batch as it is being poured either by passing
the receptacle completely through the discharge stream or by completely diverting a section.
, What is the time limitation between obtaining the sample and completing the tests? - Answer
15 minutes
What is the minimum sample size for compressive strength cylinders? - Answer 1 cf
How often do temperature measuring devices require calibration? - Answer At least annually
What is the acceptable temperature range of freshly mixed concrete? - Answer 30°F-120°F
+/- 1°F
What is the minimum concrete cover requirement when taking temperature, in all directions? -
Answer 3"
When should temperature readings be recorded? - Answer At least 2 and up to 5 minutes
after insertion; once the reading has stabilized
To what accuracy are temperature readings read? - Answer +/- 1°F
What is the purpose of testing the slump of plastic concrete? - Answer To determine how
much water is in the concrete and how it is likely to perform.
In which ASTM section can the allowable ranges of slump be found? - Answer ASTM C94:
Standard Specification for Ready-Mixed Concrete
What are the tolerance limits for slumps in the following ranges?
A. </= 2"
B. (2",4")
C. >/= 4" - Answer A. +/- 1/2"
B. +/- 1"
C. +/- 1 1/2"
What equipment is needed to properly conduct a slump test? - Answer Non-absorbent mat,
slump cone, 5/8" diameter rod that is 24" long, dump bucket
In which ASTM section is the slump test procedure detailed? - Answer ASTM C143
To what accuracy is the slump test result read? - Answer +/- 1/4"
Questions with Guaranteed Pass
Solutions.
What are the four basic ingredients of concrete? - Answer Cement, water, coarse aggregate,
and fine aggregate
What indicators are used to evaluate the quality of freshly mixed or hardened concrete with an
emphasis on compressive strength (think field tests)? - Answer Slump, Temperature, Air
Entrained
What is hydration? - Answer A complex chemical process that produces heat and accounts
for the majority of the strength gain of concrete.
What are negative effects of a high w/c ratio? - Answer Cracking, shrinkage, strength
reduction
Should you sample the concrete before or after job-site water is added? - Answer After
What is the max expected value of the air content in non-air entrained concrete? - Answer
2%
What are the effects of air entrainment? - Answer Increased workability and freeze-thaw
resistance, decreased bleeding and compressive strength
What are the two most important details on the concrete batch ticket? - Answer Mix
designations and batch time
What are the time and rotation limitations on batch-to-placement? - Answer 90 minutes,
300 rotations
Should you accept or reject a batch with an unapproved mix designation? - Answer Reject
How do you properly obtain a composite sample from a truck? - Answer Mix two samples
together ideally taken from the middle 1/3 of the batch as it is being poured either by passing
the receptacle completely through the discharge stream or by completely diverting a section.
, What is the time limitation between obtaining the sample and completing the tests? - Answer
15 minutes
What is the minimum sample size for compressive strength cylinders? - Answer 1 cf
How often do temperature measuring devices require calibration? - Answer At least annually
What is the acceptable temperature range of freshly mixed concrete? - Answer 30°F-120°F
+/- 1°F
What is the minimum concrete cover requirement when taking temperature, in all directions? -
Answer 3"
When should temperature readings be recorded? - Answer At least 2 and up to 5 minutes
after insertion; once the reading has stabilized
To what accuracy are temperature readings read? - Answer +/- 1°F
What is the purpose of testing the slump of plastic concrete? - Answer To determine how
much water is in the concrete and how it is likely to perform.
In which ASTM section can the allowable ranges of slump be found? - Answer ASTM C94:
Standard Specification for Ready-Mixed Concrete
What are the tolerance limits for slumps in the following ranges?
A. </= 2"
B. (2",4")
C. >/= 4" - Answer A. +/- 1/2"
B. +/- 1"
C. +/- 1 1/2"
What equipment is needed to properly conduct a slump test? - Answer Non-absorbent mat,
slump cone, 5/8" diameter rod that is 24" long, dump bucket
In which ASTM section is the slump test procedure detailed? - Answer ASTM C143
To what accuracy is the slump test result read? - Answer +/- 1/4"
