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This set of Basic Civil Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Grades of Cement”.

1. What does grade 33 cement indicate?
a) Tensile strength of 33 kN/m2
b) Tensile strength of 33 N/mm2
c) Compressive strength of 33 kN/m2
d) Compressive strength of 33 N/mm2

Explanation: The grades of cement are specified by IS 1489-1991. Cements are usually graded based on their compressive strength.

2. Ordinary Portland cement (OPC) has been classified into how many grades?
a) 2
b) 3
c) 10
d) 5

Explanation: There was only one grade of OPC before 1987 and was according to IS 269-1976. It was revised in 1991 and IS 1489-1991 included 3 grades namely, 33 grade, 43 grade and 53 grade.

3. Grade 43 OPC is used widely for:
a) High rise buildings
b) Plastering
c) House construction
d) Finishing works

Explanation: Grade 43 OPC has higher strength than grade 33 and lower than grade 53. Grade 33 used for finishing works under normal condition. Grade 53 is used for high rise building.

4. After how many days is the strength of cement is tested and graded according to the result?
a) 7 days
b) 28 days
c) 1 day
d) 14 days

Explanation: Cement blocks are prepared to test their compressive strength. With proper curing and attaining strength, these can be tested. It requires 28 days to fully cure and attain the strength of required grade, say 43 N/mm2 for grade 43 OPC.

5. The compressive strength of OPC increases with time:
a) True
b) False

Explanation: Cement blocks can be tested at 1 day, 3 days, 7 days and 28 days. Usually 1 day doesn’t give any result. Strength of 43 grade OPC at the end of 3 days is 23, 7 days is 33 and 28 days is 43. So, it increases with time.

6. Grade 43 OPC shall be rejected if it remains in bulk storage in the factory for:
a) More than 3 months
b) More than 1 month
c) More than 6 months
d) More than 4 months

Explanation: Cement stored in the factory of more than 6 months has to be retested and rejected if it does not meet requirements. Time period of more than 3 months is for cement bags with vendors.

7. The ratio of percentage of alumina to iron oxide in OPC 43 grade is:
a) 3.5
b) 0.66
c) 0.1
d) 0.05

Explanation: It is mentioned in IS 8112:2013 Table 2. 3.5 is the total sulphur content, 0.1 is chloride content and 0.05 is alkali content.

8. What is the required minimum fineness for grade 53 OPC?
a) 370 m2/kg
b) 370 cm2/g
c) 580 m2/kg
d) 580 cm2/g

Explanation: The value is in accordance with the IS code 12269 for 53 grade OPC. Table 3 gives physical requirements and fineness is one of them.

9. Which of the following cannot be added in 33 grade OPC after burning stage?
a) Gypsum
b) Water
c) Colouring Agents
d) Clay

Explanation: The details and specifications regarding the manufacture of 33 grade OPC are mentioned in IS 269. It says that after burning, only certain element like gypsum, water, performance enhancers, colouring agent can be added. More raw material-clay cannot be added.

10. How much maximum percentage by mass of performance improvers can be added in grade 33 OPC?
a) 0.5
b) 1
c) 5
d) 0.1