Concrete ACI Certification Exam - Questions and Answers What must be done if the concrete drops below the top of the Slump mold while the top layer is
... [Show More] being rodded? Add additional concrete to keep an excess of concrete above the top of the mold at all times Rod each layer ___ times uniformly over the cross section with the rounded end of the rod. 25 The slump mold is filled in _____ layers. 3 layers True or false the slump mold should be in a dry condition before beginning the test? False. For use in the slump test, the tamping end on both ends of the tamping rod must be... Rounded to a hemispherical tip True or false the Anterior surface of the slump mold is allowed to have minor irregularities? False The mold for making the slump test is in the shape of The frustum of a cone What is the maximum allowable time between obtaining the first and final portion of the composite samples? 15 minutes True or false the sample of concrete used for temperature determination must be rodded 25 time? False What is the required shape of the tamping end of the tamping rod? Rounded to a hemispherical tip Is 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. True or false after the final rodding, the sides of the slump should be tapped lightly with the tamping rod False Prior to lifting the mold, concrete must be removed from _____. the area surrounding the base If rodding is the method of consolidation being used, the measure must be filled in how many layers? 3 For a measure of 14 L [0.5 ft^3], what is the required number of strokes of the tamping rod for consolidation of each layer? 25 When rodding the middle and top layers, the tamping rod should penetrate into the layer below approximately how deep 1" or 25mm The end of the temperature sampling portion of the temperature measuring device is submerged a minimum of _____ into the freshly a mixed concrete 3" After the temperature of the concrete is read, what is then required? Report the temperature What must be done to the concrete surrounding the temperature measuring device after the device is submerged in the fresh concrete? Gently press the concrete around the device to prevent air from impacting the temperature read. What must be done to the sample container prior to sampling the concrete? Dampen (with water) True or false the temperature of concrete may be measured in a wheelbarrow True The temperature of the concrete is reported to the nearest Degree The direct reading of the final liquid level in the neck of the air meter, Is estimated to the nearest 0.25% True or false it is necessary to tap the sides of the measuring bowl after each layer has been rodded True What must be done if there is a slight deficiency in the quantity of concrete in the measure following consolidation of the final layer? Add a small quantity of representative concrete before strike off What tools may be used to strike off the top surface of the concrete following consolidation of the final layer? A strike-off bar; a metal, glass, or acrylic plate After rodding each layer, what should be done to the measure before adding another layer of concrete? Tap the sides of the measure smartly 10 to 15 times with the mallet In rodding the sample, how deep should the rod penetrate each layer? Rod bottom layer to full depth; rod second and final layer penetrating the previous layer about 25 mm (1 in.) When rodding the concrete sample, what is the specified number of strokes required for each layer? 25 If the concrete sample is to be consolidated by rodding, the measure is filled in _____ layers. 3 equal If portions of undisturbed concrete are found in the air meter at the end of the test what must be done The test is then considered invalid and must be redone. True or false after molding test specimens, you should wait two hours before moving them to the locations of initial storage. False, they should be moved to initial storage as soon as possible Define Yield: The amount of material gathered in regards to the amount of material expected from the design Calculate yield ratio (Measure of filled mold - measure of empty mold) / volume of mold True or false: when the concrete contains large aggregate, the testing technician should wet-sieve the sample before making unit weight tests for use in yield computations. False Which is the practice for sampling freshly mixed concrete? ASTM C172/C172M Which is the practice for testing the slump of hydraulic-cement concrete? ASTM C143/C143M Which is the standard for testing density (unit weight), yield, and air content (gravimetric) of concrete ASTM C138/C138M Which is the standard for testing air content of freshly mixed concrete by the pressure method? ASTM C231/C231M Which is the standard for testing the air content of freshly mixed concrete by the volumetric method? ASTM C173/C173M Which is the standard for making and curing concrete test specimens in the field? ASTM C31/C31M True or false: the method of determining air content of concrete containing light weight aggregate is by the pressure method False: the volumetric method (ASTM C173/C173(M)) True or false: when making a test cylinder from concrete being used in construction, the field technician must also measure the slump of the concrete. True. While the technician is checking the slump of the concrete, there is a decided falling away or shearing off of the concrete from one side of the sample. What should the technician do? A. Measure the slump directly over the original base of the mold. B. Measure the slump at the average distance above the original center. C. Disregard the test and retest on another portion of the sample D. None of the above Preparation of specimens for transport includes: A. Determination that at least 8 hours has elapsed since the final set. B. Ensuring the specimens have not been demolded C. Allowing the specimens to air dry at least 4 hours 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 air content value of 5.0% is a bread on the gauge of the same air meter containing concrete with the same aggregate, what is the correct air content? [Show Less]