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ACI Certification- Concrete Field
Testing Technician Grade 1 CP-1 (12)
A 6 by 12 in. [150 mm by 300 mm] cylinder mold can be used for concrete containing aggregate with particles not exceeding _____ in size, without the need for wet sieving the concrete. - Answer-2 in. [50 mm] A mallet weighing _____ must be used to tap the sides of the bowl after rodding each layer. - Answer-1.25 ± 0.50 lb. (600 ± 200 g) A maximum temperature of freshly mixed concrete is specified in ASTM C1064. True or False? - Answer-False A plastic container can be used for the measure in this method. True or False? - Answer-False, measure must be steel or other suitable metal After completing the strike-off procedure, what must be done before weighing the measure and sample? - Answer-Clean off any excess concrete After consolidation of the final layer, an excess of concrete _____ above the top of the measure is considered optimum. - Answer-⅛ in. [3 mm] After molding test specimens, you should wait two hours before moving them to the location of initial storage. True or False? - Answer-False; the specimens must be moved immediately After rodding each layer, what should be done to the measure before adding another layer of concrete? - Answer-Tap the sides of the measure smartly 10 to 15 times with the mallet After the final rodding, the sides of the slump mold should be tapped lightly with the tamping rod. True or False? - Answer-False Air Content Calculation Your air meter has been damaged in transit to the job site. You do, however, possess the theoretical density that was determined in the lab; it is 151.4 lb/ft3 ( kg/m3). Using the density calculated in Question 21, calculate the air content of the batch (in percentage). - Answer-5.0% = [(151.4 lb/ft3 - 143.9 lb/ft3) / 151.4 lb/ft3] × 100 5.0% = [(2425 kg/m3 - 2305 kg/m3) / 2425 kg/m3] × 100 Air meter bowls used for this test must conform to ASTM _____ and be calibrated for volume according to ASTM _____. - Answer-C231, C
ASTM C1064 - Answer-Standard Test Method For Temperature of Freshly Mixed Hydraulic-Cement Concrete ASTM C138 - Answer-Standard Test Method for Density (Unit Weight), Yield, and Air Content (Gravimetric) of Concrete ASTM C143 - Answer-Standard Test Method for Slump of Hydraulic-Cement Concrete ASTM C172 - Answer-Standard Practice for Sampling Freshly Mixed Concrete ASTM C173 - Answer-Standard Test Method For Air Content of Freshly Mixed Concrete by the Volumetric Method ASTM C231 - Answer- StandardTestMethodforAirContentofFreshlyMixedConcretebythePressureMethod ASTM C31 - Answer-Standard Practice for Making and Curing Concrete Test Specimens in the Field ASTM Method C31 gives standardized requirements for _____, _____, _____, and _____, of test specimens. - Answer-Making, curing, protecting, transporting At the end of the procedure, the air meter is _______. - Answer-Disassembled and its contents examined Concrete mixtures with specified strengths of 6000 psi [40 MPa] or greater shall have an initial curing temperature between ___________. - Answer-68 and 78 ºF [ and 26 ºC] 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? - Answer-False Cylinders made for the purpose of determining when a structure may be put into service shall be removed from the molds _________________________________________________________. - Answer-At the time of the removal of formwork Cylinders that are to be field cured are stored ___________________________ and protected _______. - Answer-In or on the structure as near to the point of deposit of the concrete represented as possible; In as near as possible the same way as the formed work Density (Unit Weight) Calculation Known: Volume of measure = 0.504 ft3 [14.27 L or 0.01427 m3] Mass of empty measure = 19.6 lb [8.89 kg]
How long should the air meter be inverted and agitated? - Answer-No more than five seconds at a time, but must be repeated for a minimum of 45 seconds to free concrete from the base How many times does the rolling operation occur? - Answer-A minimum of 2, a maximum of 3 How much time is allowed for lifting the slump mold? - Answer-5 ± 2 seconds How much time is allowed to conduct the slump test from beginning to completion? - Answer-2½ minutes If less than 1.25 L [2.5 pt] of alcohol are used, the air content is always indicated by the final meter reading. True or False? - Answer-False, if the air content is more than 9%, the number of calibrated cups of water introduced into the meter to bring the liquid level within the graduated range must be added If more than 1.25 L [2.5 pt] of alcohol are used, the final meter reading is always adjusted using _______. - Answer-A correction factor If portions of undisturbed concrete are found in the air meter at the end of the test, _________. - Answer-The test is invalid If rodding is the method of consolidation being used, the measure must be filled in how many layers? - Answer- If the air content is greater than the 9% range of the meter, __________. - Answer- Calibrated cups of water are added to bring the liquid level within the graduated range If the concrete contains aggregate larger than the maximum allowed for this test, the sample must be _____. - Answer-Wet sieved over a 1½ in. (37.5 mm) sieve If the concrete is to be consolidated by vibration, a standard 4 by 8 in. [100 mm by 200 mm] cylinder mold must be filled in _____ equal layers. - Answer- If the concrete sample contains aggregate larger than that allowed for this test, the sample must be _____. - Answer-Wet sieved over a 1-in. (25-mm) sieve If the concrete sample is to be consolidated by rodding, the measure is filled in _____ layers. - Answer-3 equal If the concrete sample is to be consolidated by vibration, the measure is filled in ______ layers. - Answer-2 equal If vibration is the method of consolidation, the measure must be filled in _____ approximately equal layers. - Answer-
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? - Answer-Remove a representative portion of the excess concrete with a trowel or scoop 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? - Answer-True In rodding the sample, how deep should the rod penetrate each layer? - Answer-Rod bottom layer to full depth; rod second and final layer penetrating the previous layer about 25 mm (1 in.) It is necessary to tap the sides of the measuring bowl after each layer has been rodded. True or False? - Answer-True Measures other than air meter bowls used for this test must conform to ASTM _____. - Answer-C Portions of a composite sample shall be thoroughly remixed before beginning tests on the sample. True or False? - Answer-True Prior to lifting the mold, concrete must be removed from _______. - Answer-The area surrounding the base of the mold Relative Yield Calculation Using the information given and calculated in Question 22, calculate the relative yield for the batch of concrete. - Answer-1. Sampling by this method is required when tests are to be made to determine _____ with specification requirements. - Answer-Compliance Specimens shall not be transported until _______ after final set. - Answer-8h Standard Curing is the curing method used when test specimens are to be used for ______________. - Answer-Acceptance testing for specified strength, checking the adequacy of mixture proportions for strength, quality control Start molding specimens for strength tests within how many minutes after fabricating the composite sample? (Oral Exam) - Answer-15 min. Start the tests for slump, temperature, and air content within how many minutes after obtaining the final portion of the composite sample? (Oral Exam) - Answer-5 min. The approximate concrete depth (in vertical distance) after placing the first layer is _____, and the second layer is _____. - Answer-2⅝ in. [70 mm], 6⅛ in. [160 mm]
The minimum frequency of an internal vibrator used in this procedure is _____. - Answer-9000 vibrations per minute [150 Hz] The minimum size sample for making strength test specimens is _____. - Answer- cubic foot The mold for making the slump test is in the shape of _____. - Answer-The frustum of a cone The molding of strength test specimens shall begin within _____ minutes after fabricating the composite sample. - Answer- The outside diameter or side dimension of the vibrating element must be at least _____ but not greater than _____. - Answer-0.75 in. [19 mm], 1.50 in. [38 mm] The pressure method of determining air content can be used on concrete containing _____ _____ aggregate. - Answer-Relatively Dense The pressure method of determining air content cannot be used on concrete containing the following types of aggregate: _____, _____, _____. - Answer- Lightweight, air-cooled blast furnace slag, or aggregates of high porosity The sample of concrete for use in making the slump test must be obtained in accordance with ASTM Standard _____. - Answer-C172, Standard Practice for Sampling Freshly Mixed Concrete The sample of concrete used for this test is to be obtained in accordance with what ASTM Standard? - Answer-C The sample of concrete used in molding test specimens must be obtained in accordance with what ASTM Standard? - Answer-C The sample of concrete used in this test method must be obtained in accordance with what ASTM Standard? - Answer-C The sensor of the temperature measuring device shall be submerged a minimum of ______ inches into the freshly mixed concrete. - Answer-3" The slump mold is filled in _____ layers. - Answer- The slump mold should be in a dry condition before beginning the test. True or False? - Answer-False The slump of the concrete is measured and reported to the nearest _____. - Answer- ¼ in. [5 mm]
The slump test is applicable to plastic concrete with a maximum size aggregate of _____. - Answer-1½ in. The supporting surface on which specimens are stored shall be level within ______.
- Answer-1/4 in. per ft. [20 mm per m] The surface on which the slump mold will be placed must be _____. - Answer-Flat, level, moist, nonabsorbent, and free of vibration The temperature and moisture environment for field cured cylinders must be
__________. - Answer-The same as the structural work The temperature measuring device shall be calibrated ______ , or whenever there is a question of ______. - Answer-Annually, accuracy The temperature measuring device shall have a capacity of measuring temperature of freshly mixed concrete to ± ______ °F throughout a range of ____________. - Answer-1 degree, 30 degrees to 120 degrees The temperature of concrete may be measured in a wall form. True or False? - Answer-True The temperature of concrete may be measured in a wheelbarrow. True or False? - Answer-True The temperature of the concrete is reported to the nearest ______ °F - Answer- degree The volumetric method of determining air content of concrete can be used on concrete containing what types of aggregate? - Answer-All types of aggregate This method covers sampling from four types of mixers, which are _____ , _____ , _____ , and _____. - Answer-Stationary mixers, paving mixers, revolving drum mixers and open top mixers Transportation time shall not exceed _____________. - Answer-4h Up to 48 hours after molding, test specimens that are to be standard cured shall be stored in a temperature range between _____ to _____. - Answer-60 and 80 ºF [ and 27 ºC] Upon completion of initial curing, the test specimens may be left in their molds and sealed in plastic bags. True or False? - Answer-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 °F [23.0 ± 2.0 °C]
What is the required minimum frequency of the vibrator used in this test method? - Answer-7000 vibrations per minute What is the required shape of the tamping end of the rod? - Answer-Rounded to a hemispherical tip What is the specified number of roddings for each layer? - Answer- What is the specified number of strokes required when rodding each layer of concrete? - Answer- What is the specified size of the mallet required for this test method when the measuring bowl has a capacity of 14 L [0.5 ft3] or less? - Answer-0.60 ± 0.25 kg [1.25 ± 0.50 lb.] What is the specified weight of the mallet used on measures that are 0.5 ft3 [14 L] or smaller? - Answer-1.25 ± 0.50 lb. [600 ± 200 g] What method of consolidation must be used when the slump is greater than 3 in. [ mm]? - Answer-Rodding What method of consolidation must be used when the slump is less than 1 in. [ mm]? - Answer-Vibration What must be done if the concrete drops below the top of the slump mold while the top layer is being rodded? - Answer-Add additional concrete to keep an excess of concrete above the top of the mold at all times What must be done if there is a slight deficiency in the quantity of concrete in the measure following consolidation of the final layer? - Answer-Add a quantity of representative concrete before strike off What must be done if there is an excessive amount of concrete in the measure following consolidation of the final layer? - Answer-Remove a representative quantity of concrete with the scoop or trowel before the strike off What must be done to the concrete surrounding the temperature measuring device after the device is submerged in the fresh concrete? - Answer-Close off air voids by gently pressing the concrete around the device What must be done to the sample container prior to sampling the concrete? - Answer-Dampen with water What must occur before a sample of concrete can be taken from a revolving drum mixer? (Oral Exam) - Answer-All of the water must be added to the mixer
What should be done if the concrete contains aggregate larger than is appropriate for the size of the molds or equipment being used? (Oral Exam) - Answer-Wet sieving What tools may be used to strike off the top surface of the concrete following consolidation of the final layer? - Answer-A strike-off bar; a metal, glass, or acrylic plate What type of alcohol and concentration must be used in this test method? - Answer- Isopropyl, 70% by volume (65% by weight) When consolidating a flexural strength test specimen by rodding, rod one stroke for each _____ of top surface area. - Answer-2 square inches When consolidating the concrete by vibration, how many times should the vibrator be inserted into each layer? - Answer-Three (3) When filling the measuring bowl of the air meter, the concrete must be placed in _____ layers of equal depth. - Answer- When internal vibration is used to consolidate a standard flexural strength test specimen, the technician should insert the vibrator at intervals not exceeding _____ along the center line of the beam. - Answer-6 in. [150 mm] When large amounts of alcohol are used, the direct reading will tend to indicate a __________ air content. - Answer-Higher When raising the slump mold, it should not be rotated or twisted. True or False? - Answer-True When rodding a standard 6 by 12 in. [150 mm by 300 mm] cylinder, each layer must be rodded _____ times. - Answer- When rodding each upper layer of concrete in a cylinder, the tamping rod should penetrate into the underlying layer by about _____. - Answer-1 in. [25 mm] When rodding the bottom layer, the tamping rod must be _____ to uniformly distribute the strokes. - Answer-Slightly inclined When rodding the concrete sample, what is the specified number of strokes required for each layer? - Answer- When rodding the middle and the top layers, the tamping rod should penetrate into the layer below approximately _____. - Answer-1 in. [25 mm] When sampling from a revolving drum truck mixer, concrete must be sampled at a minimum of _____ regularly spaced intervals during discharge of the middle portion of the batch. - Answer-
