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A comprehensive guide to the aci certification exam, covering a wide range of questions and answers related to the volumetric method of determining air content in concrete. It covers the requirements for the test equipment and the procedures for obtaining the concrete sample, filling the measuring bowl, and reading the final liquid level. The document also addresses issues such as the maximum size of aggregate, the need for wet sieving, the number of layers and strokes required, the use of the funnel, the adjustment of the liquid level, and the handling of air content values outside the meter's range. This guide is an invaluable resource for anyone preparing for the aci certification exam.
Typology: Exams
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The volumetric method of determining air content of concrete can be used on concrete containing what types of aggregate? - Correct Answer-All types of aggregate What are the requirements for the tamping rod used in this test method? - Correct Answer-Round, straight 5/8 [16mm] +/- 1/16 in. [2 mm] diameter rod at least 4 in. [ mm] greater in length than the depth of the bowl being used, with the tamping end rounded to a hemispherical tip of the same diameter, made of steel, high-density polyethylene, or other plastic of equal or greater abrasion resistance. What are the requirements for the strike-off bar used in this test method? - Correct Answer-Flat, straight steel bar at least 1/8 by 3/4 by 12in. [3 by 20 by 300 mm] or a flat, straight high-density polyethylene bar, or other plastic of equal or greater abrasion resistance, at least 1/4 by 3/4 by 12in. [6 by 20 by 300 mm]. What is the approximate volume of the measuring cup used to add water to the air meter, in relation to the volume of the air meter bowl? - Correct Answer-1.00% +/- 0.04% What type of alcohol and concentration must be used in this test method? - Correct Answer-Isopropyl, 70% by volume (65% by weight) A mallet weighing ______ must be used to tap the sides of the bowl after rodding each layer. - Correct Answer-1.25 +/- 0.50 lb. (600 +/- 200g) The sample of concrete used in this test method must be obtained in accordance with what ASTM standard? - Correct Answer-C The maximum size aggregate allowed in this test method is _______. - Correct Answer- 1-1/2" (37.5 mm) If the concrete sample contains aggregate larger than that allowed for this test, the sample must be _______. - Correct Answer-Wet sieved over 1-in. (25 mm) sieve. When filling the measuring bowl of the air meter, the concrete must be placed in ____ layers of equal depth. - Correct Answer- What is the specified number of strokes required when rodding each layer of concrete?
The initial quantity of water and alcohol added to the air can poured directly into the neck of the top section of the air meter. True or False? - Correct Answer-False, the funnel must be used. 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? - Correct Answer-Bottom of the meniscus. How long should the air meter be inverted and agitated? - Correct Answer-No more than 5 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? - Correct Answer-A minimum of 2, a maximum of 3. Why is the isoproyl alcohol added to the meter? - Correct Answer-To dispel any foam that may be on the surface of the water. The direct reading of the final liquid level in the neck of the air meter, is estimated to the nearest ________. - Correct Answer-1/4% (0.25%) If the air content is greater than the 9% range of the meter, __________. - Correct Answer-Calibrated cups of water are added to bring the liquid level within the graduated range. In order for an initial meter reading to be valid, the meter must not be leaking, the liquid level must stablize within 6 minutes, and the foam on the surface of the liquid must not be greater than 2 full percent divisions. True or False? - Correct Answer-True 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? - Correct 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 _________. - Correct Answer-A correction factor. When large amounts of alcohol are used, the direct reading will tend to indicate a ________ air content. - Correct Answer-Higher At the end of the procedure, the air meter is ______. - Correct Answer-Disassembled and its contents examined If portions of undisturbed concrete are found in the air meter at the end of the test, ________. - Correct Answer-The test is invalid.