ACI Concrete Field-Testing Technician Grade I Certification Actual Exam V2 (Latest Update 2026 / 2027) Questions & Answers | Grade A | 100% Correct

ACI Concrete Field-Testing Technician Grade I Certification Actual Exam V2 (Latest Update 2026 / 2027) Questions & Answers | Grade A | 100% Correct Question: The Method of determining air content of concrete containing lightweight aggregate is the pressure method. True or False? False Answer When making a test cylinder from concrete being used in construction, the field technician must also measure the slump of the concrete. True or False? True While the technician is checking the slump of the concrete, there is a decided falling away or shearing off of concrete from one side of the sample. What should the technician do? Disregard the test and retest on another portion of the sample Preparation of specimens for transport includes Determining that at least 8 hours has elapsed since the final set If the aggregate correction factor for a given source of fine and coarse aggregate is found to be .2% in a pressure air meter, and an air content value of 5.0% is read on the gage of the same air meter containing concrete with the same aggregate, what is the correct air content in %. 4.8% = 5.0 - 0.2 Strength test specimens transported from the field to the testing laboratory must be Protected from jarring, moisture loss, and freezing. Test for slump and air content must be started within __ after obtaining the final portion of the composite sample. 5 mins The minimum size for samples to be used for strength tests is __. 1 ft^3 = 28 L For normal strength concretes, what temperature range must be maintained for test cylinders during initial curing? 60-80 deg F When the concrete contains large aggregate, the testing technician should wet-sieve the sample before making density (unit weight) tests for use in yield computations. True or False? False When determining the temperature of fresh concrete, what is the minimum amount of concrete cover in all directions around the sensor of the temperature measuring device? 3 in = 75 mm The sides of the slump mold should be lightly tapped to consolidate the concrete in the mold. True or False? False Unless specified otherwise, strength test specimens molded from concrete having a slump less than 1 in. (25mm) must be consolidated by vibration. True or False? True Tamping rod should be (what shape)? rounded Start molding strength test specimens within (how many) minutes after fabricating the composite sample. 15 mins ASTM C173 specifies a minimum time requirement for inverting and agitating the meter to free concrete from the base. True or False? True It is acceptable to fabricate a test specimen from the same concrete used for the air content test. True or False? False According to ASTM C138, what is the air content (in percent) of the following concrete batch? The theoretical density computed on an air-free basis is 168 lb/ft^3 The density is 158 lb/ft^3 6.0%= [(168 - 158)/168] x 100 Representative samples are required for use in tests conducted for the purpose of determining compliance with the specifications for concrete quality. True or False? True After strike off of the measure used to determine density, a small quantity of concrete may be added to correct a deficiency. True or False? False Test cylinders may be capped with a thin layer of portland cement paste which is permitted to harden and cure with the specimen. True or False? True For concrete with aggregates less than 3 inches, the thermometer must remain in the fresh concrete sample a minimum of 5 minutes or until the temperature reading stabilizes. (T or F) False (2-5 minutes) The temperature measuring device must be accurate to within 0.1 degree. (T or F) The temperature measuring device shall have a capacity of measuring temperature of freshly mixed concrete throughout a range of _____ to _____ degree F ( ______ to ______ degree C) 30 to 120 degree F ( 0 to 50 degree C) A composite sample is not needed if only the temperature test is being run. (T or F) True The temperature of fresh concrete in a placement must be measured by inserting a thermometer into the top six inches of concrete. (T or F) False (3 in.) The temperature of the concrete is recorded to the nearest ______ degree F (______ degree C) 1 degree F (0.5 degree C) 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. (T or F) Calibrate the temperature measuring device at least __________, or whenever there is a question of accuracy. Annually After the thermometer is placed in the concrete: Gently press concrete around the thermometer According to ASTM C1064, what is one reason to take the temperature of concrete? Verify conformance It is allowable to remove the temperature measuring devices from the freshly mixed concrete to read the temperature if you cannot see the reading. (T or F) False The maximum allowable time between obtaining the first and last portions of the composite sample may not exceed 5 minutes. (T or F) False Start molding specimens for strength tests within 30 minutes after fabricating the composite sample. (T or F) False (15 mins) The composite concrete sample must be protected from sun, wind, contamination and rapid evaporation. (T or F) False (Contamination and rapid evaporation) 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. (T or F) False (wet screened) The composite sample not be remixed before beginning any tests. (T or F) False Sampling should normally be performed, as the concrete is discharged from the mixer. (T or F) True ASTM Method C172 includes the sampling from stationary mixers, paving mixers, truck mixers, agitators, and non-agitating equipment. (T or F) True After sampling is completed, start the tests for slump and air content within: None of the above (5 mins) In any case, do not obtain samples until: All the water and admixtures have been added to the concrete No samples shall be taken before ______ or after ______ of the batch has been discharged. When strength tests are to be made, the minimum size of the composite sample shall be: 1 cubic foot Sample the concrete from the chute of a truck mixer by: Fresh concrete to be tested at the job site should be sampled from: Two or more regularly spaced intervals during discharge of the middle portion of the batch The elapsed time between obtaining the first and final portions of the composite sample, according to ASTM C172, shall not exceed: None of the above The sides of the slump cone should be tapped with the mallet to consolidate the concrete in the mold. (T or F) False For the slump test, when Rodding the second layer and the top layer, the tamping rod should just penetrate into the underlying layer. (T or F) True According to ASTM C143, it is permissible to use a mold, which clamps to a non-absorbent base. (T or F) True When filling the final layer of the slump cone, never heap the concrete above the top of the mold. (T or F) False The filling of the slump cone should be done in three layers of equal height. (T or F) False The slump test may be done on any flat surface. (T or F) False When filling the slump cone, each layer should be rodded 25 times. (T or F) True The slump cone is filled in three layers of equal volume. (T or F) True Concrete should be removed from around the base before the cone is lifted. (T or F) True The slump cone should be raised carefully, vertically upward, in a steady motion in ________ Seconds 3 to 7 The elapsed time between the start of filling the slump cone and the removal of the cone must be no more than: 2 1/2 minutes The slump should be measured to the nearest Quarter of an inch In order to determine slump, you should measure the vertical distance from: Top of the mold to the displaced original center of the top surface The dimensions of the slump cone are: Top diameter 4 inches, bottom diameter 8 inches, height 12 inches In the slump test, if a decided falling away or shearing off the concrete from one side or portion of the mass occurs upon raising the slump cone, one should: Disregard the test and make a new test on another portion of the sample The slump cone should be struck-off with: The tamping rod The slump cone must be placed: On a flat moist, non-absorbent, rigid surface When rodding the second and third layers, the rod should penetrate the preceding layer by about 1 inch. (T or F) True The normal ½ cubic foot bucket may not be used to determine Density (unit weight) of lightweight concrete. (T or F) False (0.2 bucket) Concrete slump of less than 1 inch should be consolidated using a vibrator. (T or F) True ASTM C138 states, "the minimum capacity of the bucket depends on the maximum slump requirement." (T or F) False According to ASTM C138, after rodding each layer, tap the sides of the container, with the rod exactly 25 times. (T or F) False The outside of the density bucket should be cleaned before weighing. (T or F) True Concrete with a slump less than 1 inch should be rodded 25 times per layer. (T or F) False (Use Vibrator) According to C138, concretes with slumps of 1-3 inches may be compacted with the vibrator or the rod. (T or F) True The unit weight bucket must be calibrated at least once a month. (T or F) False According to ASTM C138, when rodding the bottom layer, the rod shall not forcibly strike the bottom of the measure. (T or F) True The strike-off plate must be: At least 1/4 inch thick if metal At least 1/2 inch thick if glass or acrylic Flat (All of the above) Given the following: wt of bucket 16.2 lbs, volume of bucket =0.498 cf, wt of bucket and concrete 88.5 lbs. 177.2 lb/ft^3 What is the optimum amount of the concrete that should be protruding above the top of the mold after the third layer has been tapped by the mallet? About a 1/8th inch After strike-off, the next operation is: Clean the excess concrete from the exterior of the measure Strike-off density (unit weight) bucket by: Using a flat plate in a sawing motion If the density (unit weight) of concrete is 146 lb/ft³ and the total batch weight is 35,468 lb., what is the yield? 9.0 yd^3 The tamping, rod used for the unit weight test: A round, straight steel rod Has a 5/8 diameter with the tamping end rounded Is approximately 24 inches in length (All of the above) For a design batch of 9.0 cubic yards, the total weight of all materials batched was 36,400 lb., and the actual yield was 9.5 cubic yards. What was the relative yield? 1.06 Determine the air content. Total material batched 37,500 lbs...design yield 9.0 yd³...theoretical unit wt. 150.0 lbs/ft³...actual unit wt. 140.0 lbs/ft³ actual yield 9.6 yd³ 6.7% The pressure method should be used for determining the air content of concrete containing lightweight aggregates. (T or F) False The aggregate correction factor should only be used when concrete containing lightweight aggregate is being tested. (T or F) False After consolidation, if the measure contains a great excess of material, remove a quantity of representative concrete then strike off the surface. (T or F) True ASTM C231 covers procedures for both Type A and Type B meters. (T or F) True During filling with water, once water emerges through the opposite petcock, the Type B pressure meter should be jarred to expel all air bubbles through the petcock. (T or F) True Using the Type B meter, the gauge should read to the nearest 0.1%. (T or F) True Wet sieving is needed when the sample of fresh concrete contains aggregates larger than 2 inches. (T or F) True After the Type B pressure meter is filled with water and all the air has been expelled through the petcock: Close the bleeder valve and pump up the pressure chamber and adjust the gauge to the initial pressure line Given that the reading on the pressure gauge is 5.3 percent, unit weight=143.7 lbs/cf, slump=6.5 inches, and aggregate correction factor is 0.2 percent, what is the air content? To determine the air content use the Type B meter: Read the gauge and subtract the aggregate correction factor After the Type B meter bowl is struck-off, cleaned and the lid is clamped on: Open the main air and air bleeder valves, open both petcocks and fill with water Just Prior to adding concrete to the bowl you should: Dampen the bowl and place it on a flat, level, non-absorbent, and firm surface Rod each Layer of concrete: Exactly 25 times This test method cannot be used to determine the air content of concrete containing lightweight aggregates. (T or F) False The rollameter base should be filled in three equal layers by volume. (T or F) False (2 layers) Isopropyl alcohol is used only at the end of the test procedures to dispel foam. (T or F) False The rollameter should never be used when ambient temperatures are below 60°F. (T or F) False If the concrete contains coarse aggregate particles that would be retained on a 1-1/2 in sieve, the concrete must be wet sieved to remove large sizes before testing in the rollameter. (T or F) True The rollameter may be used for concretes containing lightweight or normal weight aggregates. (T or F) True The calibrated measuring cup is equivalent to approximately 1% of the volume of the bowl of the air meter. (T or F) True Always add isopropyl alcohol prior to the initial filling of the meter with liquid. (T or F) False (Pint of water first) Immediately after water is added and the cap is tightened, the next step is: Invert and agitate the unit for at least 45 seconds Which of the following equipment is not used in the ASTM C173 tests? Strike off plate After the meter had been rolled twice with no change in the liquid level and no foam on the surface of the liquid, the direct reading of the liquid in the neck was 3.25%. What was the air content of the concrete? The aggregate correction factor is 0.3% & 2 pints of alcohol were added initially. Read the liquid level in the neck, estimating to the nearest: 0.25% After the top is clamped on, fill the rollameter with liquid by: Using the funnel until the liquid appears in the neck The rolling procedure must be performed: With the neck of of the rollameter elevated Standard concrete specimens for comprehensive strength tests should be "initially" cured at 50 to 90° F. (T or F) False Standard compressive strength specimens for acceptance may be 6 X 12 or 4 X 8 inch cylinders. (T or F) True While rodding the top two layers, ASTM C31 requires the rod to penetrate the preceding Layer by 4 inches. (T or F) False Standard concrete test cylinders shall be molded on a level surface as near as practicable to its initial curing location. (T or F) True Never tap the sides of a compression test specimen with the mallet. (T or F) False 4 X 8 inch cylinders that are rodded should be filled in 3 layers of equal volume. (T or F) The top of the cylinders should be covered after molding with: 25 times When rodding ASTM C31 specimens, each layer should be rodded how many times? A plastic sheet or bag A plastic cap or lid A non-absorptive, non reactive plate (Any of the above) Standard cured compressive test specimens cannot be transported from the field to the laboratory until: 8 hours after final set Light-gauge single use molds, susceptible to damage if tapped with the mallet should Be tapped with: An open hand Cylinders shipped from the field to the laboratory for testing must be: Protected from physical damage Protected from moisture loss Protected from freezing (All of of the above) Final curing for concrete test cylinders for the basis of acceptance that are standard cured: Shall be with moisture maintained on all surfaces at 73.5 +/-3.5 degree F Sampling Fresh Concrete: Collecting a representative sample of concrete to be tested is as important as executing the test methods to obtain _______________________________. Accurate results (Reference 1.2) Sampling Fresh Concrete: This practice covers sampling from four types of equipment , which are ________________________________, ________________________, ________________________________________, and _____________________ ____________. Stationary mixers, paving mixers, revolving truck mixers, continuous mixers (Reference 1.5) Sampling Fresh Concrete: The elapsed time between obtaining the first and final portions of the composite sample shall not exceed ____________________. 15 minutes (Reference 1.5) Sampling Fresh Concrete: Portions of a composite sample shall be thoroughly remixed before beginning tests on the sample? True or False? True (Reference 1.5.5) Sampling Fresh Concrete: Start tests for slump, temperature, and air content within ________________ after obtaining the final portion of the composite sample. 5 minutes (Reference 1.5.5 & Figure 1.6) Sampling Fresh Concrete: Start molding specimens for strength tests within ___________________ after fabricating the composite sample. 15 minutes (Reference 1.5.5 & Figure 1.6) Sampling Fresh Concrete: The concrete sample must be protected from contamination and ______________________. Evaporation (Reference 1.2) Sampling Fresh Concrete: The minimum sample for making strength test specimens is _____________________. 1 FT^3 (28 L) (Reference 1.5.1) Sampling Fresh Concrete: Where sampling from a stationary mixer, the batch must be sampled at ______ or more regularly spaced intervals during discharge of the middle portion of the batch. Two (Reference 1.5.2) Sampling Fresh Concrete: When sampling from a paving mixer, obtain samples from a least ________ difference portions of the pile and combine them into one composite sample for test purposes. Five (Reference 1.5.3) Sampling Fresh Concrete: When sampling from revolving truck mixer, sample the concrete by collecting ________ or more portions taken at regularly spaced intervals during discharge of the middle portion of the batch. Two (Reference 1.5.2) Sampling Fresh Concrete: Concrete samples from a truck mixer must be obtained before any water or admixtures are added to the mixer at the job site. True or False? False (Reference 1.5.2) Sampling Fresh Concrete: When the concrete contains aggregate larger than that permitted for a particular test method, the sample of concrete must be ______________________ before making the test. Wet screened (Reference 1.5.1) Temperature of Fresh Concrete: The stem of the thermometer is submerged a minimum of _______________________. 3 inches (75 mm) (Reference 2.4) Temperature of Fresh Concrete: The thermometer shall be capable of accurately measuring the temperature of freshly mixed concrete to _____________________ throughout a range of _________________________. 1 degree F (+/- 0.5 degree C), 30 to 120 degree F (0 to 50 degree C) (Reference 2.3.2) Temperature of Fresh Concrete: The thermometer shall be verified within ___________________________________________________________________________. At least one year of its current use. (Reference 2.3.2) Temperature of Fresh Concrete: The temperature of concrete may be measured in a wheelbarrow. True or False? True (Reference 2.3.2) Temperature of Fresh Concrete: The temperature of concrete may be measured in a wall form. True or False? True (Reference 2.3.2) Temperature of Fresh Concrete: A composite sample of concrete is required even if the only purpose for obtaining the sample is to determine temperature. True or False? False (Reference 2.3.3) Temperature of Fresh Concrete: What must be done to the sample container prior to sampling the concrete? Dampened (with water) (Reference 2.3.3) Temperature of Fresh Concrete: What must be done to the concrete surrounding the thermometer after the device is submerged in the fresh concrete? Push concrete around the stem to ensure the concrete is in full contact with the stem. (Reference 2.4) Temperature of Fresh Concrete: How long must the thermometer remain in the freshly mixed concrete? For 2-5 minutes. (Reference 2.4) Temperature of Fresh Concrete: After the temperature of the concrete is read, what is then required? Record the temperature. (Reference 2.4) Temperature of Fresh Concrete: The temperature of the concrete is recorded to the nearest ______________. 1 degrees F (0.5 degrees C) (Reference 2.4) Temperature of Fresh Concrete: There is a specified maximum temperature of freshly mixed concrete. True or False? False Temperature of Fresh Concrete: The sample of concrete used for temperature determination must be rodded 25 times. True or False? False Slump of Fresh Concrete: When the concrete contains aggregate larger than allowed for the slump test, the large aggregate must be ______________________________________________________________________________ _. Wet screened over 1-1/2 in. (37.5 mm) sieve. ( Reference 3.5) Slump of Fresh Concrete: The mold for making the slump test is in the shape of ______________________________________________________________________________ ____________________. The frustrum of a cone. (Reference 3.5) Slump of Fresh Concrete: The height of the slump mold is _____________________. 12 in. ( 300 mm) (Reference 3.5) Slump of Fresh Concrete: The interior surface of the slump mold is allowed to have minor irregularities. True or False? False (Reference 3.5) Slump of Fresh Concrete: For use in the slump test, the tamping end or both ends of the tamping rod must be ____________________________________________________________. Rounded to a hemispherical tip. (Reference 3.5) Slump of Fresh Concrete: The slump mold should be in a dry condition before beginning the test. True or False? False (Reference 3.5) Slump of Fresh Concrete: The surface on which the slump mold will be placed must be _________________, __________________, _______________, _________________________, and ____________________. Flat, level, damp, nonabsorbent, and rigid. (Reference 3.5) Slump of Fresh Concrete: The slump mold is filled in _______________ layers. Three (Reference 3.5) Slump of Fresh Concrete: Each layer should be filled approximately ____________________ the volume of the mold. One-third (Reference 3.5) Slump of Fresh Concrete: Rod each layer _______________ times uniformly over the cross section with the rounded end of the rod. 25 (Reference 3.5) Slump of Fresh Concrete: How deep should the tamping rod penetrate into each layer? Rod each layer throughout its depth; on the second and final layers, the rod should penetrate into the previous layer approximately 1 in (25 mm). (Reference 3.5) Slump of Fresh Concrete: What must be done if the concrete drops below the top of the slump mold while the top layer is being rodded? Add additional concrete to keep an excess of concrete above the top of the mold. (Reference 3.5) Slump of Fresh Concrete: Prior to lifting the mold, concrete must be removed from ______________________________________________________________________________ _______________________. The area surrounding the base of the mold (Reference 3.5) Slump of Fresh Concrete: After the final rodding, the sides of the slump mold should be tapped lightly with the tamping rod. True or False? False (Reference 3.5) Slump of Fresh Concrete: When raising the slump mold, it should not be rotated or twisted. True or False? True (Reference 3.5) Slump of Fresh Concrete: How much time is allowed for lifting the slump mold? 5 +/- 2 seconds (Reference 3.5) Slump of Fresh Concrete: The measurement for slump is made from the top of the mold to what point of the concrete specimen? The displaced original center of the top surface of the specimen. (Reference 3.5) Slump of Fresh Concrete: The slump of the concrete is measured and reported to the nearest _____________________________. 1/4 in. (5 mm) (Reference 3.5) Slump of Fresh Concrete: How much time is allowed to conduct the slump test from beginning to completion? 2-1/2 minutes (Reference 3.5) Density (Unit Weight) and Yield of Fresh Concrete: The length of the tamping rod used in this test method is ______________________________________________________________________________ ______________________________________________________________________________ _______________________________________________________________. At least 4 in. (100 mm) taller than the height of the measure but no more than 24 in. (600 mm) in overall length. (Reference 4.5.2) Density (Unit Weight) and Yield of Fresh Concrete: What is the required shape of the tamping end of the rod? Rounded to a hemispherical tip. (Reference 4.5.2) Density (Unit Weight) and Yield of Fresh Concrete: What is the required minimum frequency of the vibrator used in this test method? 9,000 vibrations per minute (150 Hz) (Reference 4.5.2) Density (Unit Weight) and Yield of Fresh Concrete: The outside diameter or side dimension of the vibrating element must be at least ____________________ but not greater than _____________________. 0.75 in. (19 mm), 1.50 in. (38 mm) (Reference 4.5.2) Density (Unit Weight) and Yield of Fresh Concrete: What material is the measure made of? Typically metal (Reference 4.5.2) Density (Unit Weight) and Yield of Fresh Concrete: What is the minimum thickness of a metal strike-off plate? 1/4 in. (6 mm) (Reference 4.5.2) Density (Unit Weight) and Yield of Fresh Concrete: What is the minimum thickness for a glass or acrylic strike-off plate? 1/2 in. (12 mm) (Reference 4.5.2) Density (Unit Weight) and Yield of Fresh Concrete: What is the specified weight of the mallet used on measures that are 1/2 ft^3 (14 L) or smaller? 1-1/4 +/- 1/2 lb. (600 +/- 200 g) (Reference 4.5.2) Density (Unit Weight) and Yield of Fresh Concrete: What method of consolidation must be used when the slump is greater than 3 in. (75 mm)? Rodding (Reference 4.7.1) Density (Unit Weight) and Yield of Fresh Concrete: What method of consolidation must be used when the slump is less than 1 in. (25 mm)? Vibration (Reference 4.7.1) Density (Unit Weight) and Yield of Fresh Concrete: If rodding is the method of consolidation being used, the measure must be filled in how many layers? Three (Reference 4.7.2.1) Density (Unit Weight) and Yield of Fresh Concrete: For a measure of 1/2 ft^3 (14 L), what is the required number of strokes of the tamping rod for consolidation of each layer? 25 (Reference 4.7.2.1) Density (Unit Weight) and Yield of Fresh Concrete: When rodding the middle and the top layers, the tamping rod should penetrate into the layer below approximately __________________________________. 1 in. (25 mm) (Reference 4.7.2.1) Density (Unit Weight) and Yield of Fresh Concrete: If the vibration is the method of consolidation, the measure must be filled in ___________ approximately equal layers. Two (Reference 4.7.2.2) Density (Unit Weight) and Yield of Fresh Concrete: If, after consolidation of the final layer, the concrete level is 1/2 in. (13 mm) above the top of the measure, what should be done? Remove enough concrete to ensure you have overfilled the measure to approximately 1/8 in. (3 mm) above the top of the measure. (Reference 4.7.2) Density (Unit Weight) and Yield of Fresh Concrete: After completing the strike-off procedure, what must be done before weighing the measure and sample? Clean off any excess concrete. (Reference 4.7.4) Density (Unit Weight) and Yield of Fresh Concrete: 17. Calculate the density of the concrete in lb/ft^3 (kg/m^3): Volume of measure = 0.504 ft^3 (0.01427 m^3) Mass of empty measure = 19.6 lb. (8.89 kg) Mass of the measure plus the concrete = 92.1 lb (41.78 kg) Calculate for both lb/ft^3 and kg/m^3. You'll need this information for future questions. 143.8 llb/ft^3 and 2305 kg/m^3 (Reference 4.7.7) Density equals net mass of concrete divided by the volume of the measure. D = 72.5 lb / 0.504 ft^3) = 143.849 (Round to tenth place) D = 32.89 kg/0.01427 m^3 = 2,304.84 (Round to whole number) Net mass of concrete: 92.1 lb (41.78 kg) - 19.6 lb (8.89 kg) = 72.5 (32.89 kg) Density (Unit Weight) and Yield of Fresh Concrete: Yield calculations: 18. The total mass of all material batched was 27,300 lb (12,383 kg). Using the density of the concrete as determined in Question 17, calculate: Density from Question 17 is 143.8 lb/ft^3 and 2,305 kg/m^3. A. Relative yield in ft^3 (M/D) = B. Relative yield in Yd^3 [M/(Dx27)] = C. Relative yield in m^3 (M/D) = A. Yield = 189.8 ft^3 (Reference 4.7.8) M/D = 27,300 lb / 143.8 lb/ft^3 = 189.847 ft (Round to tenth place) B. Yield = 7.0 yd^3 M/(Dx27) = 27,300 lb / (27 x 143.8 lb/yd^3) = 27,300 / 3882.6 lb/yd^3 = 7.031 yd^3 (Round to tenth place) C. Yield = 5.4 m^3 M/D = 12,383 kg / 2305 kg/m^3 = 5.34 m^3 (Round to tenth place) Density (Unit Weight) and Yield of Fresh Concrete: 19. Relative Yield Calculation: The volume designed for the bath (Yd) was 7.0 yd^3 (5.4 m^3). Using the yield as determined in Question 18, calculate: Yield from Question 18 is 189.8 ft^3, 7.0 yd^3, and 5.4 m^3. A. Relative yield using ft^3 (Y/Yd) = B. Relative yield using yd^3 (Y/Yd) = C. Relative yield using m^3 (Y/Yd) = 1.00 (Reference 4.7.8) A. Ry (Using ft^3) = Y/Yd = 189.8 ft^3 / (7.0 yd^3 x 27) = 189.8 ft^3 / 189 ft^3 = 1.00 B. Ry (Using yd^3) = Y/Yd = 7.0 yd^3 / 7 yd^3 = 1.00 C. Ry (Using m^3) = Y/Yd = 5.4 m^3 / 5.4 m^3 = 1.00 Density (Unit Weight) and Yield of Fresh Concrete: Air Content Calculation: Your air meter has been damaged in transit to the job site. You do, however, know the theoretical density that was determined in the lab: 151.4 lb/ft^3 (2426 kg/m^3). Using the density of the concrete calculated in Question 17, calculate: Density from Question 17 is 143.8 lb/ft^3 and 2,305 kg/m^3. (Reference 4.7.9, page 50) A. Air content (in percentage) using density in lb/ft^3: B. Air content (in percentage) using density in kg/m^3: 5.0% (Reference 4.7.9, page 50) A. Air Contention Using Density in lb/ft^3: [(151.4 lb/ft^3 - 143.8 lb/ft^3) / 151.4 lb/ft^3] x 100 = 5.0% B. Air Content Using Density in kg/m^3: [(2426 kg/m^3 - 2305 kg/m^3) x 2426 kg/m^3 x 100 = 5.0% Air Content of Fresh Concrete - Pressure Method: The pressure method of determining air content can be used on concrete containing ________________________ and __________________________ aggregate. Normal weight; heavyweight (Reference 5.2) Air Content of Fresh Concrete - Pressure Method: The pressure method of determining air content cannot be used on concrete containing the following: _______________________________________________ or _______________________________________________________. Lightweight aggregates; aggregates of high porosity (Reference 5.2) Air Content of Fresh Concrete - Pressure Method: What is the specified size of the mallet required for a typical air meter? 1-1/4 +/- 1/2 lb (600 +/- 250 g) (Reference 5.4.2) Air Content of Fresh Concrete - Pressure Method: Wet screening may be necessary when the mixture contains aggregate with a nominal maximum size greater than _______________________________________________________________. 1-1/2 in (37.5 mm) (Reference 5.4.3) Air Content of Fresh Concrete - Pressure Method: If the concrete sample is to be consolidated by rodding, the measure is filled in ___________________________________ layers. Three equal (Reference 5.6.1) Air Content of Fresh Concrete - Pressure Method: If the concrete sample is to be consolidated by vibration, the measure is filled in ___________________________________ layers. Two equal (Reference 5.6.1) Air Content of Fresh Concrete - Pressure Method: When rodding the concrete sample, what is the specified number of strokes required for each layer? 25 (Reference 5.6.1) Air Content of Fresh Concrete - Pressure Method: Vibration of the concrete sample is not allowed when the slump of the concrete exceeds ___________________. 3 in. (75 mm) (Reference 5.4.2) Air Content of Fresh Concrete - Pressure Method: In rodding the sample, how deep should the rod penetrate each layer? Rod bottom layer through full depth; rod second and final layer penetrating the previous layer about 1 in. (25 mm). (Reference 5.6.1) Air Content of Fresh Concrete - Pressure Method: After rodding each layer, what should be done to the measure before adding another layer of concrete? Rap the sides of the measure 10 to 15 times with the mallet. (Reference 5.6.1) Air Content of Fresh Concrete - Pressure Method: What tools may be used to strike off the top surface of the concrete following consolidation of the final layer? A strike-off bar or plate. (Reference 5.6.2) Air Content of Fresh Concrete - Volumetric Method (Roll-A-Meter): The volumetric method of determining air content of the concrete can be used on the concrete containing what types of aggregate? All types of aggregate. (Reference 6.2) Air Content of Fresh Concrete - Pressure Method: What are the requirements for the tamping rod used in this test method? Steel or plastic, with a hemispherical tip on one or both ends, at least 4 in. (100 mm) taller than the height of the measure but no more than 24 in. (600 mm) in overall length. (Reference 6.4.2) Air Content of Fresh Concrete - Pressure Method: What are the requirements for the strike-off bar used in this test method? Metal or plastic flat bar at least 3/4 in. (20 mm) in width and 12 in. (300 mm) in length. If using a meter made of metal, the thickness must be at least 1/8 in. (3 mm) and if using a meter made of plastic, the thickness must be at least 1/4 in. (6mm). (Reference 6.4.2) Air Content of Fresh Concrete - Pressure Method: What is the approximate capacity of the measuring cup used to add water to the air meter? 1-pint (5 ml) (Reference 6.4.2) Air Content of Fresh Concrete - Pressure Method: What type of alcohol and concentration must be used in this test method? Isopropyl, 70% by volume. (Reference 6.4.2) Air Content of Fresh Concrete - Pressure Method: A mallet weighing ________________________________ must be used to tap the sides of the bowl after rodding each layer. 1.25 +/- 0.50 lb (600 +/- 200 g) (Reference 6.4.2) Air Content of Fresh Concrete - Pressure Method: If the concrete mixture contains aggregate that would be retained on the ______________________ sieve, you must wet screen a representative portion of the concrete sample over a(n) ____________________ sieve. 1-1/2-in. (37.5 mm); 1-in. (25 mm) (Reference 6.4.3) Air Content of Fresh Concrete - Pressure Method: When filling the measuring bowl of the air meter, the concrete must be placed in _____ layers of equal volume. Two (Reference 6.6.2) Air Content of Fresh Concrete - Pressure Method: What is the specified number of strokes required when rodding each layer of concrete? 25 (Reference 6.6.2) Air Content of Fresh Concrete - Pressure Method: It is necessary to tap the sides of the measuring bowl after each layer has been rodded. True or False? True (Reference 6.6.2) Air Content of Fresh Concrete - Pressure Method: The initial quantity of water and alcohol added to the air meter can be poured directly into the neck of the top section of the air meter. True or False? False; the funnel must be used. (Reference 6.6.4) Air Content of Fresh Concrete - Pressure Method: Upon final filling of the air meter with water, what part of the liquid level should be adjusted to the zero mark on the meter? Bottom of the meniscus (Reference 6.6.4) Air Content of Fresh Concrete - Pressure Method: How long should the air meter be inverted and agitated? No more than 5 seconds at a time, but must be repeated for a minimum of 45 seconds to free the concrete from the base. (Reference 6.6.5) Air Content of Fresh Concrete - Pressure Method: How many times does the rolling operation occur? A minimum of 2, a maximum of 3. (Reference 6.6.5) Air Content of Fresh Concrete - Pressure Method: Why is the isopropyl alcohol added to the meter? To dispel any foam. (Reference 6.6.4) Air Content of Fresh Concrete - Pressure Method: The direct reading of the final liquid level in the neck of the air meter, is estimated to the nearest ________________. 0.25% (Reference 6.6.5) Air Content of Fresh Concrete - Pressure Method: If the air content is greater than the 9% range of the meter, _______________________________________________________________. Calibrated cups of water are added to bring the liquid level with the graduated range. (Reference 6.6.5) Air Content of Fresh Concrete - Pressure Method: In order for an initial meter reading to be valid, the meter must not be leaking, the liquid level must stabilize within 6 minutes, and the foam on the surface of the liquid must not be greater than 2 full percent divisions. True or False? True (Reference 6.6.6) Air Content of Fresh Concrete - Pressure Method: If less than 2.5 pt (1.25 L) of alcohol are used, the air content is always indicated by the final meter reading. True or False? False, the air content is calculated by adding the final reading with the number of calibrated cups, if any, and subtracting the correction factor based on the amount of alcohol added. (Reference 6.6.8) Air Content of Fresh Concrete - Pressure Method: If more than 2.5 pints of alcohol are used, the final meter reading is always adjusted using ________________________________________________________. A correction factor (Reference 6.6.4 & Table 6.1) Air Content of Fresh Concrete - Pressure Method: At the end of the procedure, the air meter is __________________________________________________________________. Disassembled and its contents examined. (Reference 6.6.7) Air Content of Fresh Concrete - Pressure Method: If portions of the undisturbed concrete are found in the air meter at the end of the test, ______________________________________________________________________________ _____________________. The test is invalid. (Reference 6.6.7) Making and Curing Concrete Cylinders and Beams in the Field: For cylinders with a diameter of 6 in. (150 mm) or greater, the tamping rod must have a diameter of ____________________. 5/8 in. (16 mm) (Reference 7.4.2) Making and Curing Concrete Cylinders and Beams in the Field: The minimum frequency of an internal vibrator used in this procedure is ____________________________. 9000 vibrations per minute (150 Hz) (Reference 7.4.2) Making and Curing Concrete Cylinders and Beams in the Field: Concrete containing aggregate with particles not exceeding ______________________________________ can be used to cast specimens without the need for a wet screening. 2 in. (50 mm) (Reference 7.4.3) Making and Curing Concrete Cylinders and Beams in the Field: For concrete with a slump of less than 1 in. (25 mm), the test specimens must be consolidated by ________________________. Vibration (Reference 7.6.1) Making and Curing Concrete Cylinders and Beams in the Field: If the concrete is to be consolidated by vibration, a standard 4 by 8 in. (100 by 200 mm) cylinder mold must be filled in ______________________ equal layers. 2 (Reference Table 7.1) Making and Curing Concrete Cylinders and Beams in the Field: When rodding a standard 6 by 12 in (150 by 300 mm) cylinder, each layer must be rodded ________________ times. 25 (Reference Table 7.2) Making and Curing Concrete Cylinders and Beams in the Field: When rodding each upper layer of concrete in a cylinder, the tamping rod should penetrate into the underlying layer by about _____________________. 1 in. (25 mm) (Reference 7.6.1.1) Making and Curing Concrete Cylinders and Beams in the Field: When using an internal vibrator to consolidate a 6 by 12 in. (150 by 300 mm) compressive strength test specimen, the vibrator must be inserted at ______________ different points for each layer. 2 (Reference 7.6.1.2) Making and Curing Concrete Cylinders and Beams in the Field: When consolidating a flexural strength test specimen by rodding, rod one stroke for each ________________ along the center line of the beam. 2 in.^2 (14 cm^2) (Reference 7.6.1.1) Making and Curing Concrete Cylinders and Beams in the Field: When internal vibration is used to consolidate a standard flexural strength test specimen, the technician should insert the vibrator at intervals of ________________ along the center line of the beam. 6 in. (150 mm) (Reference 7.6.2.2) Making and Curing Concrete Cylinders and Beams in the Field: Concrete mixtures with specified strengths of 6000 psi (40 MPa) or greater shall have an initial curing temperature between __________________________________________________. 68 and 78 degrees F (20 and 26 degrees C) (Reference 7.7.1) Making and Curing Concrete Cylinders and Beams in the Field: Upon completion of initial curing, the test specimens may be left in the molds and sealed in plastic bags. True or False? False; specimens are to be demolded and placed in water storage tanks or moist rooms with free water at a temperature of 73.5 +/- 3.5 degrees F (23 +/- 2 degrees C) (Reference 7.7.1) Making and Curing Concrete Cylinders and Beams in the Field: During transportation, test specimens must be protected from damage due to ____________________________, ___________________________________, and _________________________________________. Jarring, extreme temperatures, and moisture loss. (Reference 7.7.1 Note) Making and Curing Concrete Cylinders and Beams in the Field: Specimens shall not be transported until _____________ after final set. 8 hours (Reference 7.8) Making and Curing Concrete Cylinders and Beams in the Field: Transportation time shall not exceed ________________. 4 hours (Reference 7.8) Making and Curing Concrete Cylinders and Beams in the Field: Keep field cured specimens under ____________________________________ conditions as the concrete placed for the structure. The same (Reference 7.7.2)