when quality of concrete is questionable.
**************************************************************************
ACI 318M/318RM. Determine water soluble chloride ion concentration.
Perform test once for each mix design.
][3.8.3.6
Anti-Washout Admixture
COE CRD-C 61. Determine cumulative mass loss.
Perform test once for each
350 cubic yards of underwater concrete.
]3.8.4
Non-destructive tests - use of the rebound hammer in accordance with
ASTM C 805, ASTM C 59/C 59M7, or other non-destructive processes may be
permitted by the Contracting Officer in evaluating the uniformity and
relative concrete strength in place, or for selecting areas to be cored.
Evaluate and validate test results conducted on properly calibrated
equipment in accordance with standard ASTM procedures indicated
3.8.4.1
Core Tests
Obtain and test cores in accordance with ASTM C 42. If concrete in the
structure is dry under service conditions, air dry cores (temperature 16 to
27 degrees C 60 to 80 degrees F, relative humidity less than 60 percent)
for 7 days before testing and test dry. If concrete in the structure will
be more than superficially wet under service conditions, test the cores,
after moisture conditioning, in accordance with ASTM C 42.
Take at least three representative cores from each member or
area of
concrete in place that is considered potentially deficient.
Impair the
strength of the structure as little as possible. If, before
testing, cores
show evidence of having been damaged subsequent to or during
removal from
the structure, take replacement cores.
Fill core holes with low slump concrete or mortar of a strength equal to or
greater than the original concrete.
The Contracting Office will evaluate and validate core tests in accordance
with the specified procedures. Before testing in compression, test each
core to determine pulse velocity through concrete in accordance with ASTM C
59/C 59M7. Correlate pulse velocity of concrete cores with pulse velocity
of in-place concrete.
3.8.5
Acceptance of Concrete Strength
3.8.5.1
Standard Molded and Cured Strength Specimens
When the averages of all sets of three consecutive compressive strength
test results equal or exceed the design compressive strength (f'c) or the
required field test strength (fcr) whichever is higher, and no individual
strength test falls below the specified compressive strength (f'c) or the
required field durability strength (fcr) by more than 3 MPa 500 psi,
whichever is higher. These criteria also apply when accelerated strength
testing is specified unless another basis for acceptance is specified.
SECTION 03311
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