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ACI- CONCRETE FIELD-TESTING TECHNICIAN - GRADE 1
EXAM QUESTIONS AND ANSWERS 100% PASS
"Q1. The temperature of the concrete is recorded to the nearest __________°F (______°C). - CORRECT
ANSWER ASTM C1064- (Para 7.2)
Read and record the temperature to the nearest 0.5 °C [1 °F]." "Q2. ASTM C1064 states the container used to measure temperature of concrete must be large enough to provide at least 5 inches of concrete around the sensor. A. True
B. False - CORRECT ANSWER B. False
ASTM C1064- (Para 4.1) The container shall be large enough to provide at least 75. mm [3 in.] of concrete in all directions around the sensor of the temperature measuring device." "Q3. Calibrate the temperature measuring device at least ____________, or whenever there is a question of accuracy. A. Annually B. monthly C. weekly
D. daily - CORRECT ANSWER A. Annually
ASTM C1064- (Para 5.1) The accuracy of each temperature measuring device used for determining the temperature of freshly mixed concrete shall be verified annually." "Q4. If the concrete contains aggregates larger than those that are appropriate for a size of mold or equipment used, the sample should be wet sieved before making the test. A. True
B. False - CORRECT ANSWER A. True
ASTM C172- Para (6.1)"
"Q5. The composite sample should not be remixed before beginning any tests. A. True
B. False - CORRECT ANSWER B. False
ASTM C172-Para (4.1.1) -The sample shall be combined and remixed with a shovel the minimum amount necessary to ensure uniformity and compliance with the maximum time limits" "Q6. Sampling should normally be performed, as the concrete is discharged from the mixer. A. True
B. False - CORRECT ANSWER B. False
ASTM C172-Para (5). NOTE 2—Sampling should normally be performed as the concrete is delivered from the mixer. To the conveying vehicle used to transport the concrete to the forms; however, specifications may require other points of sampling, such as the discharge of a concrete pump." "Q7. ASTM Method C172 includes sampling from stationary mixers, paving mixers, truck mixers, agitators, and non-agitating equipment. A. True
B. False - CORRECT ANSWER A. True
ASTM C172- Para (1.1)" "Q8. After sampling is completed, start the tests for slump and air content within: A. 2 ½ minutes B. 10 minutes C. 15 minutes
D. None of the above - CORRECT ANSWER D. None of the above
ASTM C172- Para (4.1.2) Start tests for slump, temperature, and air content within 5 min after obtaining the final portion of the composite sample." "Q9. In any case, do not obtain samples until: A. All the water and admixtures have been added to the concrete B. 200 revolutions of the drum have been obtained C. ½ of the water has been added
"Q13. Fresh concrete to be tested at the job site should be sampled from: A. The beginning of mixer discharge B. The last concrete discharged C. Two or more regularly spaced intervals during discharge of the middle portion of the batch
D. All of the above - CORRECT ANSWER C. Two or more regularly spaced intervals during discharge of the
middle portion of the batch ASTM C172- Para (5.2.1)." "Q14. The elapsed time between obtaining the first and final portions of the composite sample, according to ASTM C172, shall not exceed: A. 10 minutes B. 20 minutes C. 30 minutes
D. None of the above - CORRECT ANSWER D. None of the above
ASTM C172- Para (4.1) The elapsed time shall not exceed 15 min. between obtaining the first and final portions of the composite sample."
"Q15. What must occur before a sample of concrete can be taken from a revolving drum mixer? -
CORRECT ANSWER All water and admixtures must be added to the mixer.
ASTM C172- Para (5.2.3)" "Q16. Describe the different procedures that can be used to collect a sample of concrete from a stationary
or revolving drum mixer. - CORRECT ANSWER ASTM C172- (Para. 5.2.1 and 5.23)
- Repeatedly pass a receptacle through the entire discharge stream.
- Completely divert the discharge stream into a sample container." "Q17. What are the required steps for collecting a sample of concrete from a stationary or revolving drum
mixer? - CORRECT ANSWER ASTM C172- (Para. 5.2.1 and 5.2.3)
- Collect two or more portions of concrete.
- Take the portions at regularly spaced intervals.
- Take the portions from the middle of the batch."
"Q18. Describe the procedure for collecting a sample of pavement concrete deposited on grade. -
CORRECT ANSWER ASTM C172- (Para. 5.2.2)
- Discharge the contents of the paving mixer.
- Obtain samples from at least five different portions of the pile."
"Q19. What is the minimum size for a sample when strength test specimens are to be molded? - CORRECT
ANSWER The minimum size for a sample is 28 L (1 ft3)
ASTM C172- (Para. 5.1)" "Q20. What is the maximum allowable time between obtaining the first and final portions of the
composite sample? - CORRECT ANSWER The maximum allowable time= 15min
ASTM C172- (Para. 4.1)" "Q21. What action is required after the individual concrete samples have been transported to the place
where test are to be performed? - CORRECT ANSWER + Combine and remix the samples with a shovel.
ASTM C172- (Para. 4.1.1)" "Q22. What should be done if the concrete contains aggregate larger than is appropriate for the size of the
molds or equipment being used? - CORRECT ANSWER + Wet sieving
ASTM C172- (Para. 6.1)" "Q23. Start the tests for slump, temperature, and air content within how many min. after obtaining the
final portion of the composite sample? - CORRECT ANSWER + 5min
ASTM C172- (Para. 4.1.2)" "Q24. Start molding specimens for strength tests within how many min. after fabricating the composite
sample? - CORRECT ANSWER within 15 min
ASTM C172- (Para. 4.1.2)"
"Q25.From what must the concrete sample be protected? - CORRECT ANSWER + Sun, wind, and rapid
evaporation
- Contamination ASTM C172- (Para 4.1.2)"
ASTM C1064- (Para 7.1) The end of the temperature sensing portion is submerged a minimum of 75 mm [3 in.] into the freshly mixed concrete." “Q31. Start molding specimens for strength tests within 30 minutes after fabricating the composite sample. A. True
B. False - CORRECT ANSWER B. False
ASTM C172 -Para (4.1.2) - Start molding. specimens for strength tests within 15 min after fabricating the composite sample." "Q32. The maximum allowable time between obtaining the first and last portions of the composite sample may not exceed 5 minutes. A. True
B. False - CORRECT ANSWER B. False
ASTM C172 - Para (4.1)- The elapsed time shall not exceed 15 min. between obtaining the first and final portions of the composite sample." "Q33. The composite concrete sample must be protected from sun, wind, contamination and rapid evaporation. A. True
B. False - CORRECT ANSWER A. True
ASTM C172 - Para (4.1.2)" "Q34. After the thermometer is placed in the concrete: A. Gently press concrete around the thermometer. B. Cool the surface of concrete with water. C. Tap the side of the container 10-15 times.
D. All of the above - CORRECT ANSWER A. Gently press concrete around the thermometer.
ASTM C1064- (Para 7.1)
Close the void left by the placement by gently pressing the concrete around the temperature measuring device at the surface of the concrete to prevent ambient air temperature from affecting the reading." "Q35. According to ASTM C1064, what is one reason to take the temperature of concrete? A. Verify conformance B. Verify ambient air temperature C. Verify slump d.
D. None of the above. - CORRECT ANSWER A. Verify conformance.
ASTM C1064- (Para 3.1) To verify conformance to a specified requirement for temperature of concrete" "Q36. It is allowable to remove the temperature measuring devices from the freshly mixed concrete to read the temperature if you cannot see the reading. A. True
B. False - CORRECT ANSWER B. False
ASTM C1064- (Para 7.2) Do not remove the device from the concrete when reading the temperature." "Q37. The end of the temperature sensing portion of the temperature measuring device is submerged a
minimum of ____mm [__in] into the freshly mixed concrete. - CORRECT ANSWER a minimum of 75 mm
[3 in.] into the freshly mixed concrete. ASTM C1064- (Para 7.1)" "Q38. The temperature measuring device shall be verified _______or whenever there is a question
of_______ - CORRECT ANSWER verified annually, or whenever there is a question of
accuracy. ASTM C1064-(Para5.1)" "Q39 The temperature of concrete may be measured in a wheelbarrow. A. True
B. False - CORRECT ANSWER A. True"
"Q40. The temperature of concrete may be measured in a wall form.
"Q46. According to ASTM C143, it is permissible to use a mold, which clamps to a non-absorbent base. A. True
B. False - CORRECT ANSWER A. True
ASTM C143- (Para 5.2) The mold shall be sufficiently rigid to maintain the specified dimensions and tolerances during use, resistant to impact forces and shall be non-absorbent." "Q47. When filling the final layer of the slump cone, never heap the concrete above the top of the mold. A. True
B. False - CORRECT ANSWER B. False
ASTM C143-(Para 7.3) In filling and rodding the top layer, heap the concrete above the mold before rodding is started." "Q48. The filling of the slump cone should be done in three layers of equal height. A. True
B. False - CORRECT ANSWER B. False
ASTM C143-(Para 7.1) Immediately fill the mold in three layers, each approximately one third the volume of the mold." "Q49. The slump test may be done on any flat surface. A. True
B. False - CORRECT ANSWER B. False
ASTM C143-(Para 7.1) Dampen the mold and place it on a rigid, flat, level, moist, nonabsorbent surface, free of vibration." "Q50. When filling the slump cone, each layer should be rodded 25 times. A. True
B. False - CORRECT ANSWER A. True
ASTM C143-(Para 7.2) Rod each layer 25 times uniformly over the cross section with the rounded end of the rod." "Q51. The slump cone is filled in three layers of equal volume. A. True
B. False - CORRECT ANSWER B. False
ASTM C143-(Para 7.1) in three layers, each approximately one third the volume of the mold." "Q52. The elapsed time between the start of filling the slump cone and the removal of the cone must be no more than: A. 1 minute B. 2 1/2 minutes C. 5 minutes
D. 15 minutes - CORRECT ANSWER B. 2 1/2 minutes
ASTM C143-(Para 7.3) Complete the entire test from the start of the filling through removal of the mold without interruption and complete it within an elapsed time of 21⁄2 min." "Q53. The slump should be measured to the nearest A. Tenth of an inch B. Quarter of an inch C. Half of an inch
D. 1 inch - CORRECT ANSWER B. Quarter of an inch
ASTM C143-(Para 8.1) Report the slump in terms of inches [millimetres] to the nearest 1⁄4 in. [5 mm] of subsidence of the specimen during the test." "Q54. The slump cone should be raised carefully, vertically upward, in a steady motion in ________ Seconds. A. 2 to 6
ASTM C143-(Para 5.2) The rod shall have the tamping end or both ends rounded to a hemispherical tip of the same diameter as the rod." "Q60. The sample of concrete for use in making the slump test must be obtained in accordance with
Practice_______. - CORRECT ANSWER C172.
ASTM C143- (Para 6.1) The sample of concrete from which test specimens are made shall be representative of the entire batch. It shall be obtained in accordance with Practice C172." "Q61. The slump mold should be in a dry condition before beginning the test. A. True
B. False - CORRECT ANSWER B. False
ASTM C143- (Para 7.1) Dampen the mold and place it on a rigid, flat." "Q62. The approximate concrete depth (in vertical distance) after placing the first layer is________ and
second layer is__________. - CORRECT ANSWER 2 5⁄8 in. [70 mm] and second layer is 6 1⁄8 in. [160 mm]
ASTM C143- (Para 7.1) NOTE 5—One third of the volume of the slump mold fills it to a depth of 2 5⁄8 in. [70 mm]; two thirds of the volume fill it to a depth of 6 1⁄8 in. [160 mm]." "Q63. When rodding the bottom layer, the tamping rod must be __________ to uniformly distribute the
strokes. - CORRECT ANSWER slightly inclined
ASTM C143- (Para 7.2) For the bottom layer, this will necessitate inclining the rod slightly and making approximately half of the strokes near the perimeter." "Q64. What must be done if the concrete drops below the top of the slump mold while the top layer is
being rodded? - CORRECT ANSWER add additional concrete to keep an excess of
concrete above the top of the mold at all times.
ASTM C143- (Para 7.3) If the rodding operation results in subsidence of the concrete below the top edge of the mold, add additional concrete to keep an excess of concrete above the top of the mold at all times."
"Q65. Prior to lifting the mold, concrete must be removed from__________. - CORRECT ANSWER
remove concrete from the area surrounding the base of the mold. ASTM C143- (Para 7.3) Remove concrete from the area surrounding the base of the mold to preclude interference with the movement of slumping concrete." "Q66. After the final rodding, the sides of the slump mold should be tapped lightly with the tamping rod. A. True
B. False - CORRECT ANSWER B. False
ASTM C143- (Para 7.3) After the top layer has been rodded, strike off the surface of the concrete by means of a screeding and rolling motion of the tamping rod." "Q67.When raising the slump mold, it should not be rotated or twisted. A. True
B. False - CORRECT ANSWER A. True
ASTM C143- (Para 7.3) Raise the mold a distance of 12 in. [300 mm] in 5 _+ 2 s by a steady upward lift with no lateral or torsional motion."
"Q68.How much time is allowed for lifting the slump mold? - CORRECT ANSWER in 5 _+ 2 s
ASTM C143- (Para 7.3) Raise the mold a distance of 12 in. [300 mm] in 5 _+ 2 s by a steady upward lift with no lateral or torsional motion." "Q69. The measurement for slump is made from the top of the mold to what point of the concrete
specimen? - CORRECT ANSWER displaced original center of the top surface of the specimen.
ASTM C143- (Para 7.4)
NOTE 6—If the measure contains a great excess, remove a representative portion of concrete with a trowel or scoop before the measure is struck off." "Q74.In order to determine slump, you should measure the vertical distance from: A. Top of the mold to the highest point of the slumped concrete B. Top of the concrete to the base of the concrete C. Top of the mold to the displaced original center of the top surface
D. None of the above - CORRECT ANSWER C. Top of the mold to the displaced original center of the top
surface. ASTM C143- (Para 7.4) Immediately measure the slump by determining the vertical difference between the top of the mold and the displaced original center of the top surface of the specimen."
"Q75- How much time is allowed to conduct the slump test from beginning to completion? - CORRECT
ANSWER within an elapsed time of 21⁄2 min.
ASTM C143- (Para 7.4) Complete the entire test from the start of the filling through removal of the mold without interruption and complete it within an elapsed time of 21⁄2 min."
"Q76- The diameter of the tamping rod used in this test method is____________. - CORRECT ANSWER
16 mm [5⁄8 in.] _+ 2 mm [1⁄16 in.] diameter. ASTM C138- (Para 4.2) Tamping Rod—A round, smooth, straight steel rod, with a 16 mm [5⁄8 in.] _+ 2 mm [1⁄16 in.] diameter"
"Q77. What's the required shape of the tamping end of the rod? - CORRECT ANSWER rounded to a
hemispherical tip. ASTM C138- (Para 4.2) The rod shall have the tamping end or both ends rounded to a hemispherical tip of the same diameter as the rod."
"Q78. What is the required minimum frequency of the vibrator used in this test method? - CORRECT
ANSWER at least 9000 vibrations per minute [150 Hz]
ASTM C138- (Para 4.3) The vibrator frequency shall be at least 9000 vibrations per minute [150 Hz] while the vibrator is operating in the concrete." "Q79. The outside diameter or side dimension of the vibrating element
must be at least_______ but not greater than__________. - CORRECT ANSWER at least 19 mm [0.75 in.]
and not greater than 38 mm [1.50 in.] ASTM C138- (Para 4.3) The outside diameter or the side dimension of the vibrating element shall be at least 19 mm [0.75 in.] and not greater than 38 mm [1.50 in.]." "Q80. Aplastic container can be used for the measure in this test method. A. True
B. False - CORRECT ANSWER B. False
ASTM C138- (Para 4.3) A cylindrical container made of steel or other suitable metal."
"Q81. What is the minimum thickness of a metal strike-off plate? - CORRECT ANSWER at least 6 mm [1⁄
in.] thick ASTM C138- (Para 4.5) Strike-Off Plate—A flat rectangular metal plate at least 6 mm [1⁄4 in.] thick"
"Q82. What is the minimum thickness for a glass or acrylic strike-off plate? - CORRECT ANSWER at least
12 mm [1⁄2 in.] thick ASTM C138- (Para 4.5) glass or acrylic plate at least 12 mm [1⁄2in.] thick."
"Q83. What's the specified weight of the mallet used on measures that are 14 L [0.5 ft3] or smaller? -
CORRECT ANSWER 600 +_ 200 g [1.25 +_ 0.50 lb.]
"Q89. If rodding is the method of consolidation being used, the measure must be filled in how many
layers? - CORRECT ANSWER three layers
ASTM C138- (Para 6.3) Rodding—Place the concrete in the measure in three layers of approximately equal volume." "Q90. For a measure of 14 L [0.5 ft"), what is the required number of strokes of the tamping rod for
consolidation of each layer? - CORRECT ANSWER 25 strokes
ASTM C138- (Para 6.3) Rod each layer with 25 strokes of the tamping rod when nominal 14-L [0.5-ft3]." "Q91. When rodding the middle and the top layers, the tamping rod should penetrate into the layer below
approximately_________. - CORRECT ANSWER 25 mm [1 in.]
ASTM C138- (Para 6.3) For each upper layer, allow the rod to penetrate through the layer being rodded and into the layer below approximately 25 mm [1 in.]." "Q92. If vibration is the method of consolidation, the measure must be filed in ______ approximately
equal layers. - CORRECT ANSWER two
ASTM C138- (Para 6.4) Fill and vibrate the measure in two approximately equal layers." "Q93. If, after consolidation of the final layer, the concrete level is 13 mm [1/2 in] above the top of the
measure, what should be done? - CORRECT ANSWER remove a representative portion of the excess
concrete with a trowel or scoop immediately. ASTM C138- (Para 6.5) If the measure contains a great excess of concrete at completion of consolidation, remove a representative portion of the excess concrete with a trowel or scoop immediately following completion of consolidation and before the measure is struck-off." "Q94. After consolidation of the final layer, an excess of concrete _______ above the top of the measure is
considered optimum. - CORRECT ANSWER 3 mm [1⁄8 in.
ASTM C138- (Para 6.5)
An excess of concrete protruding approximately 3 mm [1⁄8 in.] above the top of the mold is optimum." "Q95. After completing the strike-off procedure, what must be done before weighing the measure and
sample? - CORRECT ANSWER clean all excess concrete.
ASTM C138- (Para 6.7) After strike-off, clean all excess concrete from the exterior of the measure." "Q96. (Unit Weight) Calculation Known: Volume of measure = 14.27 L or 0.01427 m3 [0.504 ft3] Mass of empty measure = 8.89 kg [19.6 Ib] The procedures of Test Method C138/C138M are followed, and the mass of the measure plus the concrete is found to be 41.78 kg [92.1 1b].
Calculate the density of the concrete in kg/m3 [Ib/ft3]? - CORRECT ANSWER Density of the concrete
D=(92.1-19.6)/0.504 = 143.84 Ib/ft Density of the concrete D=(41.78-8.89)/0.01427 = 2305 kg/m3" "Q97. Yield Calculations For a design batch of 5.4 m3 [7.0 yd3], the total mass of all materials batched was 12,383 kg [27,300 Ib]. Using the density of the concrete as determined in Question 96, calculate: a) The yield per batch in ft b) The yield per batch in yd c) The yield in m d) The yield per cubic yard in ft3/yd
e) The relative yield for the batch of concrete - CORRECT ANSWER ASTM C138- (Para 7.3)
a)- The yield per batch in ft3 = 27,300 Ib/143.8 (Ib/ft3) =189.8 ft b) -The yield per batch in yd3 = 27,300 Ib/143.8 x 27 (Ib/ft3) =7.031 yd c)- The yield in m3 = M/D=
