TECHNICIANS GRADE 1 (IN CANADA)
The standard practice describes the _____ _____ and _____ required to obtain a representative
sample of fresh concrete and to assess its tractability to the structure it represents. -
ANSWERSprocedures, location and sample size
The procedures used in sampling shall include the use of every precaution that will assist in
obtaining samples that are truly representative of the _____and _______ of the concrete. -
ANSWERSnature and conditions
Intermittent scooping of the sample in shovelfuls or bucketfuls into a wheelbarrow or tray as
the concrete continues to flow down the delivery chute is an acceptable technique? -
ANSWERSFalse
The concrete sample must be protected at all times from sun, wind,____and - ANSWERSrapid
evaporation, contaminants
the minimum size sample for making three 100mm diameter strength test cylinder specimens is
- ANSWERS20l for 100x200mm
The grab sample form a mixer must be obtained between the ____% and ____%points of the
discharge(except when sampling prior to the addition of a super plasticizer.) - ANSWERS10, 90
When the concrete contains aggregate whose nominal size is larger than that permitted for a
particular test method, the sample of concrete must be _____before making the test(except for
Density tests) - ANSWERSWet Sieved(over the appropriate sieve size)
,When sampling for uniformity of mixed concrete____grab samples shall be obtained from
widely separated portions of the batch during discharge - ANSWERSThree
The temperature of the concrete must be determined within ___ minutes of obtaining the grab
sample. - ANSWERS5 minutes
Air content (pressure method) measurement and slump must both be completed within ______
minutes after the sample has been transported and remixed. - ANSWERS10 minutes
Moulding of concrete strength cylinders or flexural beams must be completed within
____minutes after the sample has been transported and remixed. - ANSWERS20 minutes
Air content (volumetric method) must be started within ____ minutes after the sample has
been transported and remixed. - ANSWERS5 minutes
What document produced by the concrete supplier contains information relating to
identification of the concrete sample? - ANSWERSThe delivery ticket
Describe the operation of obtaining a sample for evaluation of concrete quality. -
ANSWERSObtain a single grab sample at one point of the discharge in as short a time as
possible.
Between what two points of the mixer discharge must the concrete be sampled? - ANSWERSthe
10% and 90% points
How is the sample obtained from the discharge stream of a mixer truck? - ANSWERSPass the
receptacle completely through discharge stream OR completely divert discharge stream into
sample container.
, What is the minimu size of sample to be obtained when strength test specimens are to be
moulded? - ANSWERS20l when 100dia x 200mm cylinder are made
30l when 150dia x 300mm cylinders are made
55l when three flexural beams are to be made
From what conditions must the concrete sample be protected? - ANSWERSSun, wind, rapid
evaporation and contamination
What must be done between taking the sample form the mixer and performing the test? -
ANSWERSTransport the sample to the place where the tests are to be performed
Remix with a shovel
What is the time limit for completion of sampling? - ANSWERS10 minutes
The test for temperature must be completed in how many minutes after obtaining the sample? -
ANSWERS5 minutes
Tests for slump and air content must be completed within how many minutes after sample has
been transported and remixed? - ANSWERS10 minutes
Moulding of strength test specimens must be completed within how many minutes after sample
has been transported and remixed? - ANSWERS20 minutes
CSA A23.2-3C gives standardized procedures for _____and ______ of test cylinders and flexural
test beams from samples of fresh concrete. - ANSWERSmaking, curing
The tamping rod must be a round, straight steel rod with a diameter of ___mm for the standard
100mm diameter cylinders - ANSWERS10mm