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1 VI SEMESTER FINAL EXAMINATION-2003 IS 2000 is allowed. product (power s assumption), calculate the capillary porosity in cement paste in % after 7 days if the water/cement ratio is [5] Q. [1] [a] Explain oxide and compound composition of cement and their roles in strengths. Also explain the role of Bogue s equation in this regard. [5] [b] Explain mineral admixtures and their roles in producing modern concrete. [5] Q. [2] [a] Explain in brief the chemical causes of concrete deterioration. [5] [b] Explain the gradation of course and fine aggregates. [5] Q. [3] [a] Explain some properties of hydrated cement paste phase as one of the major phases of concrete. [5] [b] A set of cube strengths of concrete are 25, 22, 23, 30 and 28 Mpa and they are normally distributed. Determine the characteristic strength of concrete with 95% confidence level. [5] Q. [4] [a] Explain different types of tensile strengths of concrete and their inter-relationships. [5] [b] Write the methods in selecting sand content in concrete mix design based on DOE and ACI methods. Also explain the relevant parameters. [5] Q. [5] [a] Explain workability and water cement ratio in concrete. [5] [b] Based on assumption of cement hydration (i.e 50% hydration is completed in 7 days) and also assuming that 1 cm 3 of cement produces 2 cm 3 of the hydrated Downloaded from /1

2 VI SEMESTER FINAL EXAMINATION-2005 Q. [1] [a] Ordinary Portland Cement (OPC) is admirably suitable for general concrete construction work. Justify the statement with reference of Bogu s equation. [5] [b] Explain, briefly about the differences between accelerating admixtures and retarding admixtures. [5] Q. [2] [a] Define water-cement ratio. Discuss about the quality of water for use in concrete for various purposes. [5] [b] What is bulking of aggregates? How does shape and texture of aggregates affect and strength of concrete? [5] Q. [3] [a] Discuss the effect of cyclic and dynamics loads on strength of concrete. [5] [b] At a construction site, cube test was conducted for test of compressive strenght of concrete. The strengths of 6 cubes were noted as 20, 22, 23, 22 distributed. Determine the characteristics strength of concrete with 95% confidence level. [5] Q. [4] [a] What do you understand by the Confidence Limit for a particular concrete? Determine the targe mean strength and the current margin to be used in the Mix Design if the standard deviation is 8N/mm 2 and if the characteristics strength is to be 25N/mm 2. [2+3] [b] Define durability of concrete and discuss how the water-cement ratio can affect the durability of concrete. [5] Q. [5] Write short notes on (any FOUR): [4 2.5] [i] Corrosion prevention techniques in reinforced concrete. [ii] Steam curing [iii] High Strength Concrete. [iv] Flakiness Index of Aggregate. [v] Setting time of concrete. Downloaded from /2

3 VI SEMESTER FINAL EXAMINATION-2006 Q. [1] [a] Discuss on the topic Water Requirements for Hydration. Is the Transmission zone beneficial to concrete? Describe. [2+3] [b] Explain in detail how do super-plasticizers differ form plasticizers. How can the problem of slum loss be reduced? [3+2] Q. [2] [a] Describe the various methods of compacting concrete. [5] [b] Explain in brief the general feature of cyclic loading and its effect on the behavior of concrete structures. Determine the tensile strength of a concrete cylinder mm in sizes and under standard splitting test if the load shown by the testing machine is 500KN. [2+3] Q. [3] [a] Differentiate between Nominal Mix and Design Mix concrete. What are the information required for determining Mix Design of concrete using DOE method? [3+2] [b] Write down the method of testing Aggregate Impact Value. [5] Other part of question is not available. Downloaded from /3

4 VI SEMESTER FINAL EXAMINATION-2007 Q. [1] [a] The oxide composition of cement 1 and cement 2 are as given in table. Which cement you prefer for concrete mix in cold weathering place. [5] Oxides SiO 2 CaO Fe 2 O 3 Al 2 O 3 SO 3 Free lime Cement Cement [b] What are retarders? Under what circumstances they are usually uses. [5] Q. [2] [a] Define workability of concrete. How it is determine by slump cone apparatus? [5] [b] Discuss the effects of maximum size of aggregate on he placement, workability and economy of the concrete with a given water-cement ratio. [5] Q. [3] [a] Define gel/space ratio and also discuss its strength on the properties of concrete. [5] [b] Find the mean strength, standard deviation, and coefficient of variation of the cubes given in table. [5] Cubes Strength (N/mm 2 ) Q. [4] [a] Why permeability of concrete is important for durability of concrete. [5] Downloaded from /4 [b] Write the procedure of DOE method of concrete mix design. [5] Q. [5] [a] Explain about the importance of curing the concrete strength. [5] [b] Calculate the gel/space ratio and theoretical strength of a concrete sample made with 500 gram of cement with 0.60 water cement ratio on full hydration and at 85% hydration. (Assuming that on hydration 10.0 of cement produce 2.06 c.c of gel. [8]

5 VI SEMESTER FINAL EXAMINATION-2008 Q. [1] [a] Discuss why the strength of the transition zone is generally lower than the strength of the bulk hydrated cement paste. Explain why concrete fails in brittle manner in tension but not in compression. [2+3] [b] Differentiate between setting time of concrete and setting time of cement. Which time do you think if of significance to a site engineer and why? [5] Q. [2] [a] When added to Portland cement paste in very small amounts, Calcium Chloride acts as a retarder, but in large amounts, it behaves as an accelerators. Explain the phenomenon? [b] In a cube test for various samples, the following crushing strengths were obtained. Determine standard deviation and coefficient of vibration. Use the results to determine the average design strength of the mix if only 1% of the result is allowed to fall below the minimum. The Himsworth constant (k) can be taken as Also mention how the average strength of mix can be obtained with the help of coefficient of variation. [5] Cube sample No: Crushing strength (MPa): Q. [3] [a] What are the methods available for the Concrete Mix Designing Explain any one of the them in detail. [2+3] [b] Discuss on the effects in concrete if water constants various chemical compounds. [5] Q. [4] [a] The strength of a sample of fully matured concrete is found to be 20MPa. Find the strength of identical concrete at the edge of 14 days when cured at average temperature during day time is 25 o C and nigh time at 8 o C. The Plowman s Coefficient for maturity, A and B can be taken as 21 and 61 respectively. [2+3] [b] What do you understand by the term Heat of Hydration? [5] OR, Discuss on Durability of Concrete. Q. [5] [a] Irregular shaped aggregate need more cement paste to make workable concrete. Do you agree with this statement? Justify your answer. [5] [b] Write on the acceptance criteria of concrete s strength in structures. [5] Downloaded from /5