Concrete Technology - Unit 4

Year: III

Semester: I

Frequently Asked Questions (FAQ)

Unit - 4: Hardened Concrete

1. (a) Explain the relation between tensile strength and compressive strength of concrete.

(b) Explain various factors that will effect the strength of concrete.

2. (a) What is accelerated curing? Explain its significance?

(b) Describe the procedure for assessment of compressive strength using accelerated curing method as per BIS.

3. (a) Explain Maturity concept of concrete?

(b) Discuss the Abrams water/cement ration law and its significance. How strength of concrete is estimated by w/c ratio law.

4. (a) What is the classification of concrete based on strength as per IS456.2000?

(b) Explain the method of determining flexural strength of concrete?

5. (a) Explain Maturity concept of concrete?

(b) The strength of a sample of fully matured concrete is found to be 30Mpa. Find the strength of identical concrete at age of 7 days when cured at an average temperature during daytime 14 hours at 280C and nighttime 10 hours at 150. The plowman’s constants A and B are 21 and 61 respectively.

6. (a) Explain in detail the gain of strength of concrete with age.

(b) Explain different methods of curing of concrete

7. (a) Explain the significance on gel/space ratio.

(b) Explain calculation of gel space ratio for complete hydration and partial hydration of cement.

8. List out and explain factors on which the properties of hardened concrete depends

upon.

9. (a) State and explain Abram’s w/c ratio law. Discuss its limitations.

(b) Draw the normal curves depicting the variation of compressive strength of concrete with w/c ratio and cement /water ratio.

10. (a) What do you understand by “Grade of concrete”? Discuss different grades of concrete as per IS-456-2000.

(b) Describe in detail the Accerlated curing test for concrete? Bring out its advantages and limitations.

11. (a) How does the maximum size of coarse aggregate affects the strength of Hardened concrete.

(b) Laboratory experiments conducted in Mumbai on a particular mix showed a strength of 33 MP a for a fully matured concrete. Find whether formwork can be removed for an identical concrete placed at Jammu at the age of 15 days when the average temperature is 60C. The stripping stress in concrete may be taken as 25 Mpa.The Plowman’s Constants may be assumed as 21 and 61.

Concrete Technology - Unit 3

Year: III

Semester: I

Frequently Asked Questions (FAQ)

Unit - 3: Fresh Concrete

1. (a) Explain different techniques for compaction of the concrete.

(b) With neat sketches explain performance of different types of compaction equipment.

2. Compare slump and compaction factor tests with reference to the suitability for the use of concrete under various conditions with refence to IS codal specifications.

3. (a) Explain workability of concrete?

(b) List out and briefly describe various tests to measure workability of concrete.

4. (a) Explain different techniques for transportation of the concrete.

(b) With neat sketches explain performance of different types of mixers.

(c) What is ready mixed concrete?

5. Explain procedure for determination of workability of concrete using Compaction factor test with neat diagram and give the limits of compaction factors for different workability.

6. (a) What is batching of concrete?

(b) Explain different types of bathing methods highlighting the advantages and disadvantages

7. (a) List out various operations involved in manufacturing the concrete.

(b) Explain importance of each of the operations.

8. ”Slump test is the most commonly used method of measuring workability of fresh concrete is field”. Explain in detail the slump test with the help of a neat sketch. Discuss its merits and limitations.

9. (a) What is shrinkage of concrete?

(b) Explain various factors affecting shrinkage of concrete.

(c) Describe the laboratory test for measurement of Drying shrinkage of Concrete.

10. Write short notes on:

(a) Weight batching and volume batching.

(b) Absolute volume method of proportioning mixes.

(c) Workability viz-a-viz Durability.

11. (a) What do you understand by curing of concrete? What is its importance?

(b) Explain different methods of curing fresh concrete.

12. (a) What is the effect of mixing time and temperature on workability.

(b) Discuss the various factors which influence the workability of fresh concrete.

13. (a) How does the moisture content on aggregates affect the workability of fresh concrete?

(b) With the help of neat sketch explain compaction factor test for measuring workability.

14. (a) ”A concrete technologist should have a comprehensive knowledge of workability in designing a mix”. Explain how the mix design of concrete is affected by workability

(b) Explain how the following factors affect the workability.

i. size of aggregates

ii. shape of aggregates

iii. water content

iv. grading of aggregates.

15. Explain the following with reference to the properties of fresh concrete :

(a) Segregation

(b) Bleeding

16. (a) Describe compaction factor test for measurement of workability of concrete? How is this method superior to slump test?

(b) Describe the methods available for measurement of workability of a ”low workable concrete”.

Concrete Technology - Unit 2

Year: III

Semester: I

Frequently Asked Questions (FAQ)

Unit - 2: Aggregates

1. (a) Define Bulking of fine aggregate. Explain its practical significance.

(b) Explain procedure for determining of bulking chart of fine aggregate.

2. (a) Explain the role of deleterious material present on the aggregate on the properties of concrete?

(b) What is bulking of fine aggregate? What is the effect of different zero of fine aggregate on bulking?

3. (a) Define Elongation of the aggregates. Explain their practical significance.

(b) Briefly explain procedure for determination of elongation index with sketch of the equipment.

4. Explain about moisture context and water aborption tests on aggregates? What is the significance of these tests?

5. (a) Define Fineness Modulus.

(b) Explain procedure to assess fineness modulus of fine aggregate. Explain grading of aggregates in to different grades based on Fineness Modulus.

6. (a) List out various tests on aggregates.

(b) What are the acceptable limits of various quantities and I. S. Code provision governing them.

7. Explain the significance and role of aggregates in dictating the fresh and hardened properties of concrete.

8. (a) Explain the purpose of aggregates in concrete.

(b) How does the source affects the quality of aggregate?

9. (a) Differentiate between gap grading and continuous grading of aggregate.

(b) How do you conduct sieve analysis on coarse aggregate in the laboratory.

10. Explain how the following characteristics of aggregates affect the properties of concrete.

(a) Size

(b) Shape

11. (a) How do you classify aggregates based on the shape of the particle.

(b) What is Angularity index? How is it calculated? What is its importance.

12. (a) What is the meaning of surface texture of the aggregate. Explain in detail how the surface texture influences the properties of the concrete.

(b) What are the different methods of measuring surface texture of aggregates?

13. (a) ”The bulk density of aggregate gives valuable information regarding its shape and grading”. Explain this statement.

(b) Explain the laboratory tests to determine the bulk density of aggregates.

Concrete Technology - Unit 1

Year: III

Semester: I

Frequently Asked Questions (FAQ)

Unit - 1: Cement

1. List out the chemical composition of cement with respective limits? Also explain

the role of each element on the properties of concrete?

2.

(a) Define normal consistency of cement.

(b) Explain procedure of determinig normal consistency in laboratory with details of the equipment.

3. (a) Describe the significance of Initial setting time and final setting time of cement.

(b) Explain procedure to assesses in laboratory with details of the equipment.

4. (a) Define admixture.

(b) Explain various purposes for which the admixtures are used in modifying the properties of concrete to suit specific need.

5. (a) Describe the significance of fineness of cement.

(b) Explain procedure to determine the fineness in laboratory with air permeability apparatus.

6. Explain advantages and disadvantages of concrete as a building material.

7. (a) Explain structure of a hydrated cement in different stages of hydration.

(b) Explain the process of gel formation and capillarity action during hydration.

8. Write short notes on the following:

(a) High Alumina cement

(b) Refractory cement

(c) Standard consistency of cement

(d) Coloured cement.

9. What are Bouges compounds? Explain in detail how each one of these compounds influence the strength & setting properties of cement.

10. Explain with details, in which situations each of the following cements are used

(a) Air Entraining cement

(b) Sulphate resisting cement

(c) Low heat cement

(d) Oil well cement.

11. (a) With the help of neat sketches explain how the initial and final setting time test are conducted in the laboratory using Vicot apparatus.

(b) What are I.S.codal specifications on setting times of ordinary Portland cement.

12. (a) Explain in detail the formation of Bouge’s compounds.

(b) Discuss the effect of Tricalcium Silicate on the setting properties of cement.

13. What is grade of cement? What are the different grades of cements available in the market? Does the grade of cement influences the end properties of concrete? Explain in detail?

14. (a) Explain different field tests to be conducted on cement while deciding its quality.

(b) Enumerate the different laboratory tests to be conducted on cement to decide its quality. Explain any two tests of your choice.

15. (a) Discuss the difference between the wet and dry process of manufacturing of Portland cement.

(b) Draw the flow diagrams for wet & dry process of manufacture of cement and explain the same.

16. (a) Discuss the chemical composition of ordinary Portland cement.

(b) What are the Indian Standard specifications as per I.S. 269-1989 for 33 grade ordinary Portland cement with respect to chemical requirements.

17. (a) Discuss in detail how the chemical composition of cement affects its strength and setting properties.

(b) Explain the difference between Natural and Artificial cement.

18. (a) ”The hydration of cement is an exothermic reaction”. Discuss the above statement with valid facts in connection with hydration process of cement

(b) Explain the structure of hydrated cement.