Useful tips during site work for civil engineers and technicians.

At a construction site, civil engineers and technicians manage, supervise and performs different tasks, some of which are very typical and repetitious in nature such as concrete work, schedule of material preparation, steel fixing etc.

So, here are quick guide to some points, suggestions, and tips that a site civil engineer and technician should keep in mind for quick calculations and rapid answers to site challenges and problems.

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Let continues...

The following are some basic useful tips during site work for civil engineers and technicians to keep in mind when working on a construction site.

1. Cover of concrete to the reinforcement shall be, unless shown otherwise;

Minimum: 20 mm (Varies from that depending upon Exposure condition and Fire Resistance) [Ref BS 8110:1997]

• Base - 50mm minimum to main bars
• Beams - 25mm minimum to main bars
• Slab - 15mm minimum to main bars
• Wall - 25mm minimum to main bars
• Raft slab - 100mm minimum to main bars
• Columns - 40mm minimum to main bars

2. Removal of formwork;

Position of Formwork                                      Minimum striking Time

_ Vertical sides of wall, columns, beams, etc.                   2 days

Soffits of beams & slabs (props left)                                7 days

_ Slab and props                                                           14 days

Bottom boards of piles _(intermediate support left in)     12 days

_ Soffits of beams under 6m span _                               16 days 

_ Additional: Period for each 0.6m span in                     

excess of 6m span with a maximum of 28 days                1 day _

3. The rate of application is 5 liters per square meter for any anti-termite treatment chemical used during soil sterilization

4. All hardcore beds shall be topped with a layer of fine stone or aggregates minimum size 12mm to fill the voids on the surface to receive concrete beds. 

5. The nominal maximum size of coarse aggregates should be not greater than ¼ of the minimum thickness of concrete section or element.

The four nominal aggregate sizes shall be 40mm (1½"); 20mm (3/4"); 10mm(3/8"); 6mm (¼")

6. Useful Notes on Cement

• Weight of cement one bag 50 Kg
• Volume of cement bag 35 Litres (0.035m³ )
• Density of loose cement 1440 Kg /m³  
• Specify gravity of cement 3.15
• One meter cubic of cement equal to 29 cement Bags
• Cement strength class for OPC is 32.5N, 42.5N and 52.5N

7. Nominal concrete mix and their uses;

• M 10 – 1 : 4 : 8 Used as a Blinding Concrete
• M 15 – 1 : 3 : 6 Used as a Plain Concrete
• M 20 – 1 : 2 : 4 Used as a Reinforced Concrete
• M 25 – 1 : 1.5 : 3 Used as a Reinforced Concrete
• M 30 – 1 : 1 : 2 Used as a Reinforced Concrete
• M 35 and Above - Special Concrete (Design Mix) 

8. Round steel bar and it's weight per one bar (12m long);

• 8mm - 4.736 Kg
• 10mm - 7.4 Kg
• 12mm - 10.67 Kg
• 16mm - 18.96 Kg
• 20mm - 29.63 Kg
• 25mm - 46.30 Kg
• 32mm - 75.85 Kg
• 40mm - 118.52 Kg

9. Number of round steel bar per tonne;

• 8mm - 211
• 10mm - 135
• 12mm - 94
• 16mm - 53
• 20mm - 34
• 25mm - 22
• 32mm - 13
• 40mm - 8

10. Setting time of concrete;

• Initial setting time should not be less than 30 minutes.
• Final setting time should not be greater than 10 hours. 

11. Standard plaster thickness;

• Inner plaster work : 10-12mm
• Outer plaster work: 15-20mm
• Ceiling plaster work: 6-8mm 

12. Allowable wastage for construction materials;

• Cement - 2%
• Concrete - 2 to 3%
• Sand - 7 to 10%
• Tiles - 10%
• Aggregate - 3 to 5%
• Bricks - 5% 
• Steel - 3 to 5%

13. Strength development of concrete made with local materials no admixtures;

         Age (Days)                 Strength development (% of 28 days strength)

                    1                              15%

                    3                              40%  

                    7                              65%

                  14                              85%

                  28                             99.99%

14. Basic unit of measurements at site;

               

                    1 Meter                   100 Centimeter 

                    1 Centimeter            10 Millimeter

                    1 Inch                      0.0254 Meter

                    1 Foot                     0.03048 Meter

                    25.4 Millimeter         1 Inch

                    30.48 Centimeter      1 Foot

15. Unit weight of most used materials;

• Concrete (PCC) - 2400 Kg /m³
• Steel - 7850 Kg /m³
• Concrete (RCC) - 2500 Kg /m³
• Water - 1000 Kg /m³
• Glass - 2530 Kg /m³
• Cement - 1440 Kg /m³
• Sand - 1600 to 1840 Kg /m³

16.  Normal road cross fall (camber); 

The normal cross fall for paved carriageway on tangent sections and on very flat curves with large radii, shall be:

• Asphalt concrete surfaces 2.5%
• Surface dressing surfaces 3.0%
• Stone paved surfaces 3.0%
• Gravel and earth surfaces 4.0%

17. Concrete cube samples;

• 1 – 5 m³ : 1 No.
• 6 – 15 m³ : 2 No..
• 16 – 30 m³ :3 No.
• 31 -50 m³ : 4 No.
• Above 50 m³ : 4 + 1 no. of addition for each 50 m³.

Conclusion

The "useful tips during site work for civil engineers and technicians." guide is a helpful resource that help you to solve site challenges quick. 

Hope this article will be helpful for you.

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To get access to excel sheets which can be used for various site activities click ==>HERE

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