Concrete Final Exam 2024 with complete solution;(Actual test questions and answers)

Concrete Final Exam 2024 with complete solution;(Actual test questions and answers) Prior to placing concrete for pavements or slabs on grade, what should be done? - Answer ️️ - Subgrade should be compacted, trimmed, and moistened; forms should be erected; and the reinforcing steel members should be securely in place. In hot weather, what is important to do to the subgrade? - Answer ️️ -It needs to be moistened to prevent the dry ground from sucking water out of the concrete. What is true about forms for concrete? - Answer ️️ -Wood forms should be moistened to prevent water loss from the concrete, all forms should be able to be removed from the concrete without damaging it. Steel should be clean and free of rust, steel forms can be below freezing when concrete is poured. How should concrete be deposited? - Answer ️️ -Continuously as near as possible to its final position. How do you deposit concrete on a slab pour? - Answer ️️ -It should be started along the perimeter at one end of the slab, the concrete should not be dumped in separate areas and spread out. How should concrete be placed in walls, thick slabs, or foundations? - Answer ️️ -In horizontal layers of uniform thickness, each layer should be consolidated before the next layer is added. How rapidly should concrete be placed when pouring in layers? - Answer ️️ -Fast enough to not let the previous layer set. How is concrete moved to lower elevations? - Answer ️️ -Chutes and drop chutes are used to prevent segregation of the concrete. How far can you drop concrete without segregation? - Answer ️️ -50 feet What is placed at the end of a chute to control the flow of concrete onto sloped surfaces? - Answer ️️ -A baffle How thick should the layers of freshly mixed concrete be? - Answer ️️ -6 inches to 20 inches thick for reinforced members, and 15 inches to 20 inches thick for mass work. What determines the thickness of a layer of concrete? - Answer ️️ -Width between forms and the amount of reinforcement. Should concrete be moved horizontally? - Answer ️️ -No, this causes segregation. If it has to be done it should be kept to a minimum. What should be done if pouring concrete in an area where standing water is present? - Answer ️️ -Concrete should be poured so that the concrete displaces the water ahead of it so it does not mix. How is concrete poured into a tall, narrow form? - Answer ️️ -Through an opening called a window, a hopper is used outside of the opening to control the flow of the concrete as it enters the form. How can bleeding be reduced when pouring concrete? - Answer ️️ -Pour at a slower rate or by using a concrete of a stiffer consistency, particularly when pouring the lower part of a form. How should concrete be poured into deep forms? - Answer ️️ -To avoid cracks, the concrete placement for around an hour to allow settlement of this deep member. When pouring concrete underwater, what should the slump range from, and what is the maximum W/C ratio? - Answer ️️ -6 inches to 9 inches, 0.45 What can be done to concrete in order to give it the ability to be poured under water? - Answer ️️ -Make a mix with high workability, add anti-washout admixtures, use round aggregates, use a higher percentage of fine aggregate, add entrain