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Some basic notes and formulas for civil engineers

This exclusive construction article is intended for civil engineering students. The article provides some basic notes and formulas regarding unit weight, development length, clear cover to main reinforcement, calculation of design mix etc.

Details of Unit Weight

Concrete 25 kN/m3

Brick 19 kN/m3

Steel 7850 Kg/m3

Water 1000 Lt/m3

Cement 1440 Kg/m3

1 Gallon 3.78 Litres

Link 8″ = 200mm

1 Hectare 2.471 acres(10000m2)

1 Acr 4046.82m2 = 100 cent

Given below the details of Clear Cover to Main Reinforcement

Footings: 50 mm

Raft Foundation Top: 50 mm

Raft Foundation Bottom/Sides: 75 mm

Strap Beam: 50 mm

Grade Slab: 20 mm

Column: 40 mm

Sear Wall: 25 mm

Beams: 25 mm

Slabs: 15 mm

Flat Slab: 20 mm

Staircase: 15 mm

Ret. Wall: 20/ 25 mm on earth

Water Retaining Wall: 20/30 mm

Given below the details of Development Length

Compression 38d

Tension 47 & 60d

1 Cent 435.60 Sft

1 Meter 3.2808 ft

1 M2 10.76 ft2

1 Feet 0.3048m

1 KN 100 Kg

1kN 1000N

1 Ton 1000Kg = 10,000 N = 10 kN

1 kG 9.81N

The following calculation is applied to find out the Calculation of Cement In bags

  1. PCC 1:5:10 1440/5*0.45 129.60 Kg 2.59
  2. PCC 1:4:8(M 7.5) 1440/4*0.45 162.00 Kg 3.24
  3. PCC 1:2:4(M 15) 1440/2*0.45 324.00 Kg 6.48
  4. PCC 1:3:6(M 10) 1440/3*0.45 216.00 Kg 4.32
  5. RCC 1:2:4(M 15) 144/2*0.45 324.00 Kg 6.48
  6. RCC 1:1.5:3(M 20) 1440/1.5*0.45 32.00 Kg 8.64
  7. RCC 1:1:2(M25) 370.00 Kg 7.40
  8. RCC M 30 410.00 Kg 8.20
  9. RCC M35 445.00 Kg 8.90
  10. RCC M40 480.00 Kg 9.60
  11. Damp Proof Course CM 1:3,20mm tk 1440/3*0.022 10.56 Kg 0.21
  12. 2″tk precast slab M15 324*0.05 16.20 Kg 0.32
  13. 3″tk precast slab M15 324*0.075 24.30 Kg 0.49
  14. GC Masonry CM 1:7 1440/7*0.34 70.00 Kg 1.40
  15. Brick Work CM 1:6 1440/6*0.25 60.00 Kg 1.20
  16. Brick Work CM 1:4, 115tk 1440/4*0.25*0.115 10.35 Kg 0.21
  17. Grano Flooring CC 1:1.5:3 1440/1.5*0.45*0.05 21.60 Kg 0.43
  18. Plastering CM 1:3, 12mm tk 1440/3*0.014 6.72 Kg 0.13
  19. Wall Plastering CM 1:4, 12mm tk 1440/4*0.014 5.00 Kg 0.10
  20. Laying Pressed Tiles Over a CM 1:4, 20mm tk 1440/4*0.022 7.92 Kg 0.16
  • Any Concrete Work(PCC, RCC) 0.45*35.315= 20.00
  • Damp Proof Course CM `1:3, 20mm tk 1.00
  • 2″tk Precast slab M15 1.00
  • 3″tk Precast slab M15 1.50
  • SS Masonry in CM 1:7 15.00
  • Brick Work in CM 1:6 15.00
  • Brick Work in CM 1:4,115mm tk 2.00
  • Grano Flooring in CC 1:1.5:3 1.00
  • Plastering in CM 1:3, 12mm tk 1.00
  • Wall Plastering CM 1:4, 12mm tk 1.00
  • Laying Pressed Tiles over a CM 1:4, 20mm tk 1.00
  • Ceramic Tiles, Marble, Granite, Cuddapah slab CM 1:4, 20mm tk 1.00

Calculation of Design Mix

M10 (1: 3.92: 5.62)

  • Cement: 210 Kg/ M3
  • 20 mm Jelly: 708 Kg/ M3
  • 12.5 mm Jelly: 472 Kg/ M3
  • River sand: 823 Kg/ M3
  • Total water: 185 Kg/ M3
  • Fresh concrete density: 2398 Kg/M3

M20 ( 1 : 2.48 : 3.55)

  • Cement : 320 Kg/M3
  • 20 mm Jelly : 683 Kg/M3
  • 12.5 mm Jelly : 455 Kg/M3
  • River sand : 794 Kg/M3
  • Total water : 176 Kg/M3
  • Admixture : 0.7%
  • Fresh concrete density: 2430 Kg/ M3

M25 ( 1 : 2.28 : 3.27)

  • Cement : 340 Kg/M3
  • 20 mm Jelly : 667 Kg/M3
  • 12.5 mm Jelly : 445 Kg/M3
  • River sand : 775 Kg/M3
  • Total water : 185 Kg/M3
  • Admixture : 0.6%
  • Fresh concrete density: 2414 Kg/M3
  • Note: sand 775 + 2% moisture, Water185 -20.5 = 164 Liters,
  • Admixture = 0.5% is 100 ml

M30 ( 1 : 2 : 2.87)

  • Cement : 380 Kg/M3
  • 20 mm Jelly : 654 Kg/M3
  • 12.5 mm Jelly : 436 Kg/M3
  • River sand : 760 Kg/M3
  • Total water : 187 Kg/M3
  • Admixture : 0.7%
  • Fresh concrete density: 2420 Kg/ M 3
  • Note: Sand = 760 Kg with 2% moisture(170.80+15.20)

Civil Engineering Basic Notes