UNIVERSITY OF CALIFORNIA AT BERKELEY CEE SPRING SEMESTER, 2010 Instructor: P.J. M. Monteiro Name:_____________________ CE 165 - EXAMINATION Please justify your answer in all the questions Question 1(18 points) I) Would this chemical compound make the cement particles hydrophilic or hydrophobic? ( 5 points) II) Identify the rod-like hydration product inside the air void. Which reaction generates this product? (5 points)III) Describe the hydration reaction that generates the most heat? (3 points) IV) How does the water that is absorbed by the aggregates affect the concrete’s water-to-cement ratio (5 points)Question 2 (22 points) I) For a given dosage of air-entraining agent, discuss the effect of cement content on the total amount of air-entrainment. (8 points) II) The classical slump test is not relevant for self-leveling concrete. Explain why and suggest some modifications to the test in order to measure the consistency of self–leveling concrete.(5 points) III) Discus the effect of the maximum size aggregate on the compressive strength of concrete. (4 points) IV) How does the cement composition affect the effectiveness of retarding admixtures? (5 points)Question 3 (25 points) I) Somebody list in Craig’s offers a special 25% discount in 120 bags of Portland cement that were stored for 18 months. You could save quite a bit of money if you use this cement but should you? Describe your concerns and justify your decision. (7 points) II) Does the use of hard water as mixing water for concrete affect its concrete? In your discussion, please include the effect on fresh and hardened concrete. (6 points) III) The inspector in a large project is a control freak and wants to refuse a batch of reinforcing bars because they have a little of surface corrosion. Is this justifiable? (4 points) IV) Describe two methods to the determine the amount of air in fresh concrete (8 points)Question 4 (16 points) I) What is the difference between entrapped and entrained air? (4 points) II) Describe the following terms: bull-floating, laitance and crazing, (6 points) III) Consider the mix proportions below. Which will generate the (a) the highest and (b) the lowest heat of hydration? (6 points) Mix A (lb/yd3) Cement: 500 Gravel: 1327 Water: 250 Mix B (lb/yd3) Cement: 400 Fly-Ash: 100 Gravel: 1327 Water: 250 Mix C (lb/yd3) Cement: 500 Fly-Ash: 100 Gravel: 1327 Water: 250Question 5 (19 points) I) Describe the advantages and disadvantages of using buggies for the concrete placement. (5 points) II) Why should you avoid overfinishing an air-entrained concrete? (5 points) III) An architect hires you as a concrete expert to make a concrete patio with a rock-salt finish, which is characterized by many small surface indentations. Describe the finishing steps to produce such texture (9
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