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Students in the materials lab mixed concrete with the following ingredients: 22.1 lb of cement, 41.6 lb of sand, 57.5 lb of gravel, and 14.3 lb of water. The sand has a moisture content of 3.2% and an absorption of 5.5%. The gravel has a moisture content of 3.9% and an absorption of 4.6%. Since water absorbed in the aggregate does not react with the cement or improve the workability of the plastic concrete, what is the water–cement ratio of this mix according to the American Concrete Institute’s weight mix design method? If a water-cement ratio of 0.5 is required using the same materials and ingredients but different amount of mixing water, what is the weight of the mixing water to use?
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