ASTM C31/C31M - Standard Practice for Making and Curing Concrete Test Specimens in the Field Flashcards
Practice C31/C31M gives standardized requirements for ______, ______, __________, and __________ for the test specimens.
Making
Curing
Protecting
Transporting
What diameter tamping rod is used if the diameter of the test cylinders or width of beam is:
less than 6 inches = ______
6” or greater = ______
3/8” (less than 6”)
5/8” (6” or greater)
Minimum frequency of an internal vibrator used in this procedure is:
9,000 vibrations/minute
The sampling receptacle shall be:
one of three things
Heavy gauge metal Pan
Wheelbarrow
Flat, clean non-absorbent board
Cylindrical specimens diameter shall be at least ___ times the nominal maximum size of the coarse aggregate?
3 times
Maximum aggregate size for a 4”x8” cylinder mold is __?
Maximum aggregate size for a 6”x12” cylinder mold is __?
1.25 inches for 4” x 8” cylinder mold
2 inches for a 6” x 12” cylinder mold
The sample of concrete used in molding test specimens must be obtained in accordance with what ASTM practice?
C172
When strength specimens are to be made, what three other tests must be made?
Air content
Slump
Temperature
The supporting surface on which specimens are stored shall be level within ___ per foot?
1/4” per foot
Number of vibrator insertions for a 4” diameter cylinder mold is?
1
Number of vibrator insertions for a 6” diameter cylinder mold is?
2
Number of vibrator insertions for a 9” diameter cylinder mold is?
4
When Vibrating, how many layers of concrete are required for a beam mold between 4” and 8” wide?
1
When vibrating beams under 6” wide, insert the vibrator at internals not exceeding ____ inches along the _______ of the long dimension of the specimen.
For specimens wider than 6”, use alternating insertions along _____ lines?
6 inches
Centerline
2 lines
When rodding a beam, how do you determine how many roddings are required per layer?
1 insertion for every 2 square inches of the top surface area of the beam
[ (L x W) /2 ]
When vibrating beams, after each layer has been vibrated, tap the side of the mold sharply at least ____ times with the mallet to close holes left by vibrating and to release entrapped air voids.
10 times
When vibrating, how many equal layers of concrete are required for cylinder mold (4”, 6” or 9” diameters)
2 layers
When rodding, how many equal layers of concrete are required for the following cylinder molds:
4” diameter?
6” diameter?
9” diameter?
How many roddings for each layer of each mold?
4” diameter mold - 2 layers, 25 roddings per layer
6” diameter mold - 3 layers, 25 roddings per layer
9” diameter mold - 4 layers, 50 roddings per layer
When rodding a beam mold, how many equal layers of concrete of:
beams between 4” and 8” wide?
beams over 8” wide?
2 layers for beams between 4” and 8” wide
3 layers or more for beams greater than 8” (not to exceed 6”)
For concrete with a slump less than 1”, consolidation much be done by what method?
Vibrator
For concrete with a slump between 1” and 3”, consolidation must be done by what method?
Vibrator or rodding
For concrete with a slump of over 3”, consolidation must be done by what method?
Rodding
Concrete mixtures with specified strengths of 6000 psi or greater, maintain the initial curing temperature between ___* to ___*F
68* to 78*F
For concrete mixtures with a specified strength less than 6000 psi, maintain the initial curing temperature between ___* to ___*F
60* to 80*F
Generally, no more than ___ seconds of vibration should be required for each insertion to adequately consolidate concrete w/ slump greater than 3”.
Longer if less than 3”
5 seconds
Initial curing - Store standard-cured specimens for a period up to ___ hours after molding to maintain the specified temperature and moisture conditions.
48 hours
Shield specimens from direct exposure to ____ and, if used, radiant heating devices.
Sunlight
Record the minimum and maximum _________ achieved for each set of specimens during the initial curing period.
Temperatures
Store the specimens in an environment that controls the loss of ________?
Moisture
If the specimens are made and STANDARD CURED, the resulting strength test data when the specimens are tested are able to be used for the following purposes.
(check all that apply)
a - Determination of whether a structure is capable of being put in service
b - Quality Control
c - Form or shoring removal time requirements.
d - Acceptance testing for specified strength
e - Checking adequacy of mixture proportions for strength.
d - Acceptance for strength
e - Adequacy of mixture proportions for strength.
b - Quality Control
If specimens are made and FIELD CURED, the resulting strength test data when the specimens are tested are able to be used for the following purposes.
(check all that apply)
a - Determination of whether a structure is capable of being put in service
b - Quality Control
c - Form or shoring removal time requirements.
d - Adequacy of curing and protection of concrete in the structure
e - Acceptance testing for specified strength
f - Comparison with test results for standard cured specimens or with test results from various in-place test methods
a - Is structure capable of being put in service
f - Comparison to standard cured test results
d - Adequacy of curing and protection of concrete in the structure
c - Form or shoring removal time requirements.
Cylinders that are _____ cured, are stored in or near the structure and protected same as the structure.
field
The diameter of a round vibrator shall be no more than __/__ the diameter of the cylinder mold or __/__ the width of the beam mold.
1/4 & 1/4
The combined length of the vibrator shaft + vibrating element shall exceed the depth of the section being vibrated by at least __ mm [___ in.]
75 mm [ 3 inches ]
Transportation time shall not exceed ____ hours
4 hours
Ensure that specimens have been moved to the initial curing location no later than ___ minutes after molding operations have been completed.
15 minutes
Final Curing of Cylinders - Upon completion of initial curing and within ___ minutes after removing the molds, cure specimens with free water maintained on their surfaces at all times at a regular temperature of 73.5 +/- 3.5*F
30 minutes
TRUE or FALSE:
Final curing of beams to be done in the same manner as cylinders, except that they shall be stored in water saturated with calcium hydroxide at 73.5 +/- 3.5*F
True
When field curing, store cylinders in or on the ________ as near to the point of deposit of the concrete represented as possible.
Structure
When field curing, protect all surfaces of the cylinders from the ________ in as near the same way as the _______ work.
Elements
Formed
When field curing, provide the cylinders with the same ___________ and ________ environment as the structural work.
Temperature
Moisture
TRUE or FALSE:
Specimens made for the purpose for determining when a structure is capable of being put in service shall be removed from the molds at least 1 hour prior to removal of the form work.
False - specimens shall be removed from the molds AT THE TIME of removal of form work.
