CONCRETE TECHNOLOGY

 Important Question for GTU Exam

Describe the wet process of manufacturing of cement stepwise.

2. Describe Composition of concrete in details.

3. State the different types of cement with its use.

4. Enlist and Explain functions of each Bogue’s compound.

5. Explain: ‘hydration of cement ’ and  heat of hydration’.

6. Explain: Field testing of cement.

7. Classification of aggregates based on shape.

8. Explain: Bulking of fine aggregates.

9. Describe test for fineness modulus of aggregates.

10. Explain quality of water for concrete.

11. Define workability. Discuss factors affecting workability.

12. Explain segregation and bleeding

\13.State tests on workability. Explain Slump test with sketch.

14. Explain need of curing.  State different methods of curing of concrete.

15.

 State factors affecting compressive strength of concrete.

 

16.

Write Short notes on :     1. Water/cement ratio

                                             2. Gel/Space ratio

                                             3. Effect of age on strength of concrete

 

 

17

Discuss the various factor affecting creep & effect of creep on concrete.

 

 

18

Define shrinkage. Explain in details types of shrinkage.                

 

19. Define durability. Give the various factors affecting durability.

20. Discuss the permeability phenomenon.

 21. What are the factors affecting permeability?

 22. Write short note on “Alkali aggregate reaction and sulphate attack”.

1.      Define concrete mix design. Give its objectives. List methods of concrete mix design.

2.      State the steps involved in choice of mix proportion and describe any two in detail.

3.      Using IS method of mix design, find out proportions of concrete for following data:

Grade of Concrete: M 30

Degree of Control: Very good

Maximum size of Aggregate: 20 mm

Specific gravity of Cement: 3.15

Specific gravity of FA: 2.60

Specific gravity of CA: 2.62

Condition of Exposure: severe

Workability: 0.90 CF

Note: 5% of the low results are acceptable and W/C ratio for 28 days strength of concrete is 0.49. Refer table 1 to 6.

Table– 1: Suggested valueofstandard deviation:

Grade

Concrete

Standard Deviation for Different Degree ofControl

Verygood

Good

fair

M 10

2.0

2.3

3.3

M 15

2.5

3.5

4.5

M 20

3.6

4.6

5.6

M 25

4.3

5.3

6.5

M 30

5.0

6.0

7.0

 

Table– 2 Valueoft

Accepted Proportion of

LowResults

Valueoft

1 in 5

0.84

1 in 10

1.28

1 in 15

1.50

1 in 20

1.65

1 in 40

1.86

1 in 100

2.33

 

 

Table– 3 Values ofW/Cratio and compressivestrength

CompressiveStrength in

N/mm2at 28 days

W/Cratio

20

0.60

25

0.525

30

0.48

35

0.42

40

0.375

45

0.335

 

Table– 4 W/Cratios as per DurabilityRequirements

ExposureCondition

Maximum W/Cratio

Mild

0.65

Moderate

0.55

Severe

0.45

 

 

Table– 5 Approximatelysand and water content perm3 of concrete forgradeup to M 35

Nominal maximum sizeof aggregatemm

Water content permeter cubeof concretein Kg

Sand as %oftotal aggregatebyabsolute volume

10

208

40

20

186

35

40

165

30

 

Table– 6 Approximate AirContent

Nominal Maximum size of

Aggregate in mm

Entrapped air as %of volumeof concrete

10

3.0

20

2.0

40

1.0

 

 

                                                                                                

 

 

           

 23. Design concrete mix according toIS:10262-1982recommended guide        

Lines by weight and volume  fort he following design stipulations.

 

1.  Characteristic compressive strength required at 28days=30 n/mm2

2.  Maximum size oft he aggregates =20mm (angular).

3.  Degree of workability=0.8 CF.                                                          

4.  Degree of quality control =good.

5.  Exposure=mild and water cement ratio =0.47.

6.  Cement used OPC53 grade.

7.  Specific gravity of cement, coarse aggregate and fine aggregate are

3.15, 2.6 and  2.6 respectively.

8.  Waterabsorptionofcoarseaggregateandfineaggregateare0.5%

And 1%  respectively.

9.  Free (surface) moisture in coarse aggregate and fine aggregate are nil and 2% respectively

10. Sand of zone III

11. Bulk density of cement, coarse aggregate and fine aggregate are

1440 kg/m3, 1600 kg/m3and 1800 kg/m3respectively.

12. Standard deviation is assumed to be4 N/mm2.

 

          24. State difference types of special concrete and describe light weight concrete.

          25. Write short notes on:

                                                                      1. Fiber reinforced concrete

                                                                      2. Pumped concrete

                                                                      3. Ready mix concrete

                                                                      4. Precast concrete

           26. State methods of special concreting methods.

           27. Write short notes on:

                                         1. Hot weather concreting

                                         2. Underwater concretin

           28. State Types of Non-destructive test. Explain Rebound hammer test and Ultrasonic  pulse velocity test

           29. Explain Micro cracking of concrete .

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