ACI Concrete Field Testing Technician - Grade 1 - Section 6 Air Content of Fresh Concrete (Roll-A-Meter) Questions and answers correct

ACI Concrete Field Testing Technician - Grade 1 - Section 6 Air Content of Fresh Concrete (Roll-A-Meter) Questions and answers correct The volumetric method of determining air content of concrete can be used on concrete containing what types of aggregate? All types What are the requirements for the tamping rod used in this test method? Steel or plastic; hemispherical tip; at least 4 in taller than the height of the measure but no more than 24 in. What are the requirements for the strike-off bar used in this test method? Metal or plastic flat bar at least 3/4 in in width and 12 in long. If metal - at least 1/8 in thick if plastic - at least 1/4 in thick What is the approximate capacity of the measuring cup used to add water to the air meter? 1 quart (1 L) What type of alcohol and concentration must be used in this test method? Isopropyl 70% A mallet weighing ____________ must be used to tap the sides of the bowl after rodding each layer. 1.25 +- .5 lb 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. 1.5 in: 1 in When filling the measuring bowl of the air meter, the concrete must be placed in _____ layers of equal volume. Two What is the specified number of strokes required when rodding each layer of concrete? 25 It is necessary to tap the sides of the measuring bowl after each layer has been rodded. True or False? True 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 Upon 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 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 concrete from the base. How many times does the rolling operation occur? A minimum of 2, a maximum of 3 Why is the isopropyl alcohol added to the meter? to dispel any foam The direct reading of the final liquid level, in the neck of the air meter, is estimated to the nearest ____. 0.25% If the air content is greater than the 9% range of the meter, _____. 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 stabilize within 6 min, and the foam on the surface of the liquid must not be greater than 2 full percent divisions. True or False? True If less than 2.5 pints of alcohol are used, the air content is always indicated by the inal 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. If more than 2.5 pints of alcohol are used, the final meter reading is always adjusted using _____. A correction factor At the end of the procedure, the air meter is ________. Disassembled and its contents examined