**Civil Engineering Interview Questions, ****Basic knowledge**

**Basic knowledge**

**Topic – Cement**

- What is the density of cement ?

** Ans.** Density 1440 kg / cu

- What is the volume of 1 bag (50 kg ) cement ?

**Ans.** Volume of 1 bag of cement = 0.0347 cum

- How many bags of cement in 1 cum ?

**Ans.** 1 cum = 28.8 bag

- What is the intial and final setting time of cement?

**Ans**. Initial setting time = 30 min

Final setting time = 10 hrs

- What is the difference between OPC and PPC?

** Ans**.** OPC** = 95 % Cement clinker & 5 % Gypsum, It Gain Early strength as compare to PPC

**PPC** = 75 % Cement clinkers , 5% gypsum and 20 % flyash, It has Slower heat hydration compare to OPC.

- How to check quality of cement on site?

**Ans**. Below mentioned tests are the simple tests which you can perform easily on site to find out the quality of cement with no apparatus.

**Date of manufacturing** – Cement loss strength with time, Retesting after 3 months.

Percentage of Cement Strength reduction with age

3 months 20%-30%

6 months 30%-40%

12 months 40%-50%

**Floating test – **Take a handful of cement and throw it in water, a good quality of Cement should sink and should not float on water.

**Color** – The colour of cement should be uniform. An ideal colour of cement is grey with a light greenish shade.

**Check for lumps – **Lumps are formed due to the presence of moisture in cement.

- What is the tolerance of cement weight ?

** Ans. **± 0.5 % of total weight (more than 25 ton ) as per IS 12269

-2 % and + 5 % For 50kg bag as per IS 12269

- What are the cement testing Frequency?

**Ans.** Per batch or Per Week number

- Standard specification for Cement Storage as per IS 41182: 1996

** Ans. **Cement bags shall be stacked off the floor on wooden planks in such a way as to keep about 150 mm to 200 mm clear above the floor. A space of 600 mm minimum shall be left alround between the exterior walls and the stacks. The height of stack shall not be more than 10 bags to prevent the possibility of lumping up under pressure.

- IS Specification for cement (PCC)

S No | Test Description | Test Method | Limits as per IS 1489 Part 1: 1991 |

1.0 | Initial setting time (min) | IS 4031 Part 5:1988 | Minimum: 30 min |

2.0 | Final setting time (min) | IS 4031 Part 5:1988 | Maximum: 600 min |

3.0 | Fineness by blaine’s method (m^{2}/Kg) | IS 4031 Part 2:1999 | Minimum: 300 m^{2}/Kg |

4.0 | Compressive strength @ 3 days (N/mm^{2}) | IS 4031 Part 6:1988 | Minimum: 16 N/mm^{2} |

5.0 | Compressive strength @ 7 days (N/mm^{2}) | IS 4031 Part 6:1988 | Minimum: 22 N/mm^{2} |

6.0 | Compressive strength @ 28 days (N/mm^{2}) | IS 4031 Part 6:1988, RA2009 | Minimum: 33 N/mm^{2} |

7.0 | Soundness by le-chatelier’s Method (mm) | IS 4031 Part 3:1988, RA2009 | Maximum: 10 mm |

8.0 | Drying shrinkage (%) | IS 4031 Part 10:1988 | Maximum: 0.15% |

- IS Specification for cement (OPC 43 grade)

S No | Test Description | Test Method | Limits as per IS 8112: 2013 |

1.0 | Initial setting time (min) | IS 4031 Part 5:1988, RA2009 | Minimum: 30 min |

2.0 | Final setting time (min) | IS 4031 Part 5:1988, RA2009 | Maximum: 600 min |

3.0 | Fineness by blaine’s method (m^{2}/Kg) | IS 4031 Part 2:1999, RA2008 | Minimum: 225 m^{2}/Kg |

4.0 | Compressive strength @ 3 days (N/mm^{2}) | IS 4031 Part 6:1988, RA2009 | Minimum: 23 N/mm^{2} |

5.0 | Compressive strength @ 7 days (N/mm^{2}) | IS 4031 Part 6:1988, RA2009 | Minimum: 33 N/mm^{2} |

6.0 | Compressive strength @ 28 days (N/mm^{2}) | IS 4031 Part 6:1988, RA2009 | Minimum: 43 N/mm^{2} |

7.0 | Soundness by le-chatelier’s Method (mm) | IS 4031 Part 3:1988, RA2009 | Maximum: 10 mm |

- IS Specification for cement (OPC 53 grade)

S No | Test Description | Test Method | Limits as per IS 12269: 2013 |

1.0 | Initial setting time (min) | IS 4031 Part 5:1988, RA2009 | Minimum: 30 min |

2.0 | Final setting time (min) | IS 4031 Part 5:1988, RA2009 | Maximum: 600 min |

3.0 | Fineness by blaine’s method (m^{2}/Kg) | IS 4031 Part 2:1999, RA2008 | Minimum: 225 m^{2}/Kg |

4.0 | Compressive strength @ 3 days (N/mm^{2}) | IS 4031 Part 6:1988, RA2009 | Minimum: 27 N/mm^{2} |

5.0 | Compressive strength @ 7 days (N/mm^{2}) | IS 4031 Part 6:1988, RA2009 | Minimum: 37 N/mm^{2} |

6.0 | Compressive strength @ 28 days (N/mm^{2}) | IS 4031 Part 6:1988, RA2009 | Minimum: 53 N/mm^{2} |

7.0 | Soundness by le-chatelier’s Method (mm) | IS 4031 Part 3:1988, RA2009 | Maximum: 10 mm |

Read more

- Soundness test of cement by Le Chatelier
- INITIAL AND FINAL SETTING TIME OF CEMENT IS 4031-Part 5
- Compressive strength of the cement cubes
- Fineness test of Cement by dry sieving method 90 micron sieve

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