addition to the mix design to better identify
deficient concrete.
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ACI 214R tests for strength - conduct strength tests of concrete during
construction in accordance with the following procedures:
a.
Mold and cure six 150 by 300 mm 6 by 12 inch cylinders from each
sample taken in accordance with ASTM C 31/C 31M. Prevent
evaporation an d loss of water from the specimen.
b.
Test cylinders in accordance with ASTM C 39. Test one cylinder
at 3 days, two cylinders at 7 days, two cylinders at 28 days, and
hold one cylinder in reserve. The compressive strength test
results for acceptance shall be the average of the compressive
strengths from the two specimens tested at 28 days. If one
specimen in a test shows evidence of improper sampling, molding or
testing, discard the specimen and consider the strength of the
remaining cylinder to be the test result. If both specimens in a
test show any defects, the Contracting Officer may allow the
entire test to be discarded.
c.
If the average of any three consecutive strength test results is
less than the specified strength (f'c) or the minimum test
strength (fcr) for durability, whichever is higher, by more the 3
MPa 500 psi, take a minimum of three core samples in accordance
with ASTM C 42, from the in-place work represented by the low test
results. Locations represented by erratic core strengths shall be
retested. Remove concrete not meeting strength criteria and
provide new acceptable concrete. Repair core holes with nonshrink
grout. Match color and finish of adjacent concrete.
d.
Strength test reports shall include location in the work where the
batch represented by a test was deposited, batch ticket number,
time batched and sampled, slump, air content (where specified),
mixture and ambient temperature, unit weight, and water added on
the job. Reports of strength tests shall include detailed
information of storage and curing of specimens prior to testing.
e.
Final reports shall be provided within 7 days of test completion.
[3.8.3.4
Air Content
ASTM C 173 o r ASTM C 231 for normal weight concrete. Where concrete will
be exposed to deicing salts as indicated. Make air content tests on
samples from the first three batches in the placement and until three
consecutive batches have air contents within the range of the specified air
content, at which time test every fifth batch. Maintain this test
frequency until a batch is not within the specified range at which time
resume testing of each batch until three consecutive batches have air
contents within the specified range. Perform additional tests as necessary
for control. Take air content tests from planned composite samples or from
samples taken in accordance with ASTM C 172 at the point of concrete
placement.
][3.8.3.5
Chloride Ion Concentration
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NOTE: Include only when justified by size of job or
SECTION 03311
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