Concrete Technology - Dec 2014
Civil Engineering (Semester 4)
TOTAL MARKS: 80
TOTAL TIME: 3 HOURS (1) Question 1 is compulsory.
(2) Attempt any three from the remaining questions.
(3) Assume data if required.
(4) Figures to the right indicate full marks. 1 (a) What is soundness of cement? How is it tested?(4 marks) 1 (b) Define fineness modulus. Give the practical range of fineness modulus value values for coarce & fine aggregates.(4 marks)
Choose and write the Correct option.
1 (c) i) The heat of hydration of cement can be reduced by
a) Reducing the proportions of C3A &C3S
b) Increasing the proportions of C3A &C3S
c) Increasing the fineness of cement
d) Both (a) and (c)(1 marks) 1 (c) ii) Increase in fineness modulus of aggregate indicates:
a) Finer Grading
b) Coarser grading
c) Gap grading
d) None of these.(1 marks) 1 (c) iii) For a constant water-cement ratio, decrease in aggregate-cement ratio causes:
a) Increased workability
b) Decreased workability
c) No workability change
d) None of these(1 marks) 1 (c) iv) In concrete mix design, allowance for bulking of sand is necessary in case of :
a) Volume batching only
b) Weight batching only
c) Both (a) and (b)
d) None of these.(1 marks) 1 (d) What do you understand by Rapid hardening cement? Why there is rapid rate of strength gain? Under what situations, would you recommend Rapid Hardening Cement on site?(4 marks) 1 (e) Enlist the types of admixtures. Write a short note on plasticizers.(4 marks) 2 (a) The following table depicts compressive strengths (MPa) of 20 number of concrete cubes tested in a laboratory. Calculate Average strength standard deviation and coefficient of variation.
|Sample No.||Compressive Strngth||Sample No.||Compressive Strngth||Sample No.||Compressive Strngth||Sample No.||Compressive Strngth|
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|Cement (Kg)||Water (Kg)||Sand (Kg)||Coarse Aggregates (Kg)|
Correct this proportion to suit the site conditions such that free surface moisture of sand=2% water absorption of coarse aggregates=2% coarse aggregates contain 60% of 20mm size& 40%of 12.5mm size. Report your answer in weight as well as ratios.(7 marks) 3 (b) Write a detailed note on Non Destructive Testing by using Ultrasonic Pulse velocity method. If a concrete gives pulse velocity of 2.5 km/second, give your commentss on the quality of concrete with reference to Indian standard specifications.(7 marks) 3 (c) What are the advantages of using Ready Mixed concrete?(6 marks) 4 (a) Discuss in detail, the factors affecting the durability of concrete.(10 marks) 4 (b) With a neat sketch, explain Compacting Factor Test for determining the concrete workability. For the same concrete, how are the slump value & Compacting factor related?(10 marks)
Write short notes on the following (any four)
5 (a) High Performance Concrete.(5 marks) 5 (b) Self compacting concrete.(5 marks) 5 (c) Segregation & bleeding of concrete.(5 marks) 5 (d) Retarders used structure.(5 marks) 5 (e) Distress in concrete structures.(5 marks) 6 (a) Explain spilt Tensile Test, with a neat sketch.(8 marks) 6 (b) Discuss high volume fly ash concrete.(6 marks) 6 (c) How many minimum concrete compressive test result are needed for a particular concrete grade on site, to fix up value of standard Deviation? In the absence of test results, what is the value of standard deviation would you adopt for designing M25 concrete mix, as per Indian standard specification?(3 marks) 6 (d) The concrete mix design is carried out as per Indian Standard Method for M20 concrete. The crushing strength test result of three cubes after 28 days of curing are 12N/mm2,20N/mm2& 30 N/mm2 can this result be accepted? If not ,give the specific reasons.(3 marks)