ACI CERTIFICATION EXAM COMPLETE
QUESTIONS AND VERIFIED SOLUTIONS
◉ What are the two types of sampling? Answer: Evaluation of the
concrete quality
Evaluation of the uniformity
◉ Define the evaluation of the concrete quality sampling type.
Answer: Involves obtaining a single concrete sample at the
appropriate location within the load.
◉ Define the evaluation of the uniformity sampling type. Answer:
Shows how good the mixing process is.
Obtain 3 samples from distinct portions of the load, and compare the
resulting slump, plastic air and density values.
◉ The sampling procedure describes the _____ , _____ , and _____ _____
required to obtain a representative sample of fresh concrete.
Answer: procedures, location, sample size
◉ When sampling from a truck or mixer, take sample between _____
and _____ % of discharge. What is the EXCEPTION for this? Answer:
10, 90
,When slump is tested immediately prior to addition of
superplasticizer
◉ Define grab sampling. Answer: Securing at one point of the
discharge the required volume needed in as short a period of time as
possible.
◉ More than one container may be used to obtain a single grab
sample. True or false? Answer: True
◉ When sampling for uniformity, add water after sampling has
started. True or false? Answer: False
◉ When sampling for uniformity, do not allow mixer to turn in the
mixing direction. True or false? Answer: True
◉ What is the minimum size of sample for a 100x200 mm cylinder?
Answer: 20L
◉ What is the minimum size of sample for a 150x300 mm cylinder?
Answer: 30L
◉ What is the minimum size of sample for a 150x150x535 mm
flexural beam? Answer: 55L
,◉ If there are more than 3 cylinders/beams, increase the min
volume ______________. Answer: equal to the volume of extra
specimens, plus 10%
◉ You need bigger samples for air content and slump tests. True or
false? Answer: False; smaller samples
◉ Describe the 2 methods of sampling. Answer: Pass a receptacle
completely through the discharge stream.
Divert discharge into a sample container.
◉ How do you regulate the rate of discharge from a truck? Answer:
Rate of revolution of the drum (NOT by size of gate opening)
◉ Obtain, transport, and remix the sample within ______ minutes.
Answer: 10
◉ For density tests, use an _________ sample. Answer: unsieved
◉ If concrete contains larger aggregate than appropriate, wet sieve
the sample before testing. True of false? Answer: True
, ◉ Compressive strength is most important and most tested. True or
false? Answer: True
◉ Once you have done the on sight curing, cylinders can be tested
for compressive strength. True or false? Answer: False
◉ When specimens are cured and then tested, they may be used for
_________ , ________ , and ________. Answer: acceptance testing for
specified strength,
checking adequacy of mixture proportions for strength,
quality control
◉ You should not use cardboard moulds unless the document says
to. However, at what strength should cardboard moulds never be
used? Answer: 35 MPa or greater
◉ What is the maximum variation in cross-section for flexural test
moulds? Answer: 3mm
◉ What size of tamping rod do you use for 100x200 mm diameters?
Answer: 10mm +/- 1mm
450-600mm length
At least one rounded hemispherical end
QUESTIONS AND VERIFIED SOLUTIONS
◉ What are the two types of sampling? Answer: Evaluation of the
concrete quality
Evaluation of the uniformity
◉ Define the evaluation of the concrete quality sampling type.
Answer: Involves obtaining a single concrete sample at the
appropriate location within the load.
◉ Define the evaluation of the uniformity sampling type. Answer:
Shows how good the mixing process is.
Obtain 3 samples from distinct portions of the load, and compare the
resulting slump, plastic air and density values.
◉ The sampling procedure describes the _____ , _____ , and _____ _____
required to obtain a representative sample of fresh concrete.
Answer: procedures, location, sample size
◉ When sampling from a truck or mixer, take sample between _____
and _____ % of discharge. What is the EXCEPTION for this? Answer:
10, 90
,When slump is tested immediately prior to addition of
superplasticizer
◉ Define grab sampling. Answer: Securing at one point of the
discharge the required volume needed in as short a period of time as
possible.
◉ More than one container may be used to obtain a single grab
sample. True or false? Answer: True
◉ When sampling for uniformity, add water after sampling has
started. True or false? Answer: False
◉ When sampling for uniformity, do not allow mixer to turn in the
mixing direction. True or false? Answer: True
◉ What is the minimum size of sample for a 100x200 mm cylinder?
Answer: 20L
◉ What is the minimum size of sample for a 150x300 mm cylinder?
Answer: 30L
◉ What is the minimum size of sample for a 150x150x535 mm
flexural beam? Answer: 55L
,◉ If there are more than 3 cylinders/beams, increase the min
volume ______________. Answer: equal to the volume of extra
specimens, plus 10%
◉ You need bigger samples for air content and slump tests. True or
false? Answer: False; smaller samples
◉ Describe the 2 methods of sampling. Answer: Pass a receptacle
completely through the discharge stream.
Divert discharge into a sample container.
◉ How do you regulate the rate of discharge from a truck? Answer:
Rate of revolution of the drum (NOT by size of gate opening)
◉ Obtain, transport, and remix the sample within ______ minutes.
Answer: 10
◉ For density tests, use an _________ sample. Answer: unsieved
◉ If concrete contains larger aggregate than appropriate, wet sieve
the sample before testing. True of false? Answer: True
, ◉ Compressive strength is most important and most tested. True or
false? Answer: True
◉ Once you have done the on sight curing, cylinders can be tested
for compressive strength. True or false? Answer: False
◉ When specimens are cured and then tested, they may be used for
_________ , ________ , and ________. Answer: acceptance testing for
specified strength,
checking adequacy of mixture proportions for strength,
quality control
◉ You should not use cardboard moulds unless the document says
to. However, at what strength should cardboard moulds never be
used? Answer: 35 MPa or greater
◉ What is the maximum variation in cross-section for flexural test
moulds? Answer: 3mm
◉ What size of tamping rod do you use for 100x200 mm diameters?
Answer: 10mm +/- 1mm
450-600mm length
At least one rounded hemispherical end
