hw2solutions - CM3400: Assignment No. 2 Due Date: Monday...

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CM3400: Assignment No. 2 Due Date: Monday 03/23/09 1. If water from an untested source is to be used for concrete manufacturing, what is the requirement for strength? What are the impurities that we need to control to avoid detrimental effects? Water should not affect the setting time, 7-day mortar cube strength f’ c >90% f’ c of distilled water Impurities that are needed to avoid are as follows: Chlorides, carbonates, bicarbonates, sulfate, salts, sea water, sugar, and oils. 2. List the basic types of Portland cement, and describe their characteristics and uses. Type Compound Characteristics (%) Fineness Characteristics Uses C 3 S, C 2 S, C 3 A, C 4 AF (m 2 /kg) Type I 55, 19, 10, 7 370 General Purposes Type II 51, 24, 6, 11 370 Moderate Sulfate Resistance Type III 56, 19, 10, 7 540 High Early Strength Type IV 28, 49, 4, 12 380 Low Heat of Hydration Type V 38, 43, 4, 9 380 High Sulfate Resistance 3. What modification is made to concrete to increase its resistance to freeze-thaw damage? Air-entrainment 4. Explain the benefits and drawbacks (if any) of using retarders, accelerators, silica fume, and super-plasticizers. Admixture Benefits Drawbacks Retarders Slow the rate of setting, facilitate workability during high ambient temperatures, somewhat waterreducing Some early strength loss Accelerators Accelerates the strength development May increase the drying shrinkage and corrosion risk, may discolor concrete, may reduce late strength, Increase permeability Silica Fume Reduces permeability, air content, bleeding and
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This note was uploaded on 06/22/2009 for the course CM 3400 taught by Professor Hassan during the Spring '09 term at LSU.

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hw2solutions - CM3400: Assignment No. 2 Due Date: Monday...

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