Basic Knowledge for a Civil Site Engineer

 

Site engineer needs to play out a great deal of exercises on the site. His/her job includes a ton of obligation which incorporates offering adequate guidance and oversight when there are any specialized issues, or for appropriate administration and for the planning of everyday reports of the development works. There are a few works which are repeating and henceforth a couple of tips may be helpful for a structural architect in the event that they are recollected. They help in quicker computations just as to address issues at the site. 😆 😉 

Why you need this article

As a site engineer

you should have basic knowledge on struture ,Concrete and bar bending Scheldule while you are handeling a project. For fresher these points should be always set on their mind .While you are handeling any project ,without zero knowledge it will be shame for you so i hope this article shall be helpful for a site engineers.

Basic Points to be remember

    • Lapping: Lapping  for the bars is not allowed having diameters more than 36 mm.
    • Chair Spacing: Chair spacing maximum spacing is 1.00 m (or) 1 No per 1m2.
    • Dowel Rods: For dowels rod minimum of 12 mm diameter should be used.
    • Rebar for Chair: Chairs minimum of 12 mm diameter bars to be used.
    • Longitudinal reinforcement : It is not less than 0.8% and more than 6% of gross C/S.
    • Rebar number for Column: Min . Bar number  for square column is 4 No’s and 6 No’s for circular column.
    • Rebar Dia for RCC Slab: Main bars in the slabs shall not be less than 8 mm (HYSD) or 10 mm (Plain bars) and the distributors not less than 8 mm and not more than 1/8 of slab thickness.
    • RCC Slab Thickness: Minimum thickness of slab is 125 mm.
    • Dimension tolerance for cubes + 2 mm.
    • Free fall of concrete is allowed maximum to 1.50m.
    • Lap slices not be used for bar larger than 36 mm.
    • Water absorption of bricks should not be more than 15 %.
    • PH value of the water should not be less than 6.
    • Compressive strength of Bricks is 3.5 N / mm2.
    • In steel reinforcement binding wire required is 8 kg per MT.
    • In soil filling as per IS code, 3 samples should be taken for core cutting test for every 100m2.

Basic Knowledge on Density of Materials

Material Density
Bricks 1600 – 1920 kg/m3
Concrete block 1920 kg/ m3
Reinforced concrete 2310 – 2700 kg/ m3

Curing Time Period

Super Sulphate cement: 7 days
Ordinary Portland cement OPC: 10 days
Minerals & Admixture added cement: 14 days

Formwork removal Time Period for difrrent RCC Members

RCC Member De-shuttering time
For columns, walls, vertical form works 16-24 hrs.
Soffit formwork to slabs 3 days (props to be refixed after removal)
Soffit to beams props 7 days (props to refixed after removal)
Beams spanning upto 4.5m 7 days
Beams spanning over 4.5m 14 days
Arches spanning up to 6m 14 days
Arches spanning over 6m 21 days

Knowledge About Cube Sample required for diffrent Concrete works

Quantity of Concrete No. of cubes required
1 – 5 m3 1 No’s
6 0 15 m3 2 No’s
16 – 30 m3 3 No’s
31 – 50 m3 4 No’s
Above 50 m3 4 + 1 No’s of addition of each 50 m3

 

Knowledge on Concrete Grade:

Grade= Cement: Sand: Aggregates
 M5 = 1:4:8 
M10 = 1:3:6 (Generally Use on PCC works) 
M15 = 1:2:4 (Generally use on Beams, Slabs) 
M20 = 1:1.5:3 (maximum use on Column, Beam and Bridge) 
M25 = 1:1:2 (use on heavy structures) 
M35 Use on Post tensioning work 
M40 Use on Pre tensioning work 

 

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CLEAR COVER TO MAIN REINFORCEMENT: 
  1. Footings : 50 mm
  2. Raft foundation Top : 50 mm
  3. Raft foundation Bottom/ sides : 75 mm
  4. Strap Beam : 50 mm
  5. Grade Slab : 20 mm
  6. Column : 40 mm (d>12mm) 25 mm (d= 12mm)
  7. Shear Wall : 25 mm
  8. Beams : 25 mm
  9. Slabs : 15 mm or not less than diameter of the bar.
  10. Flat Slab: 20 mm
  11. Staircase: 15 mm
  12. Retaining Wall on Earth: 20/ 25 mm
  13. Water retaining structures: 20 / 30 mm
  14. Sunshade (Chajja) : 25 mm
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WEIGHT OF STEEL ROD (BAR) FOR 1m LENGTH:
Volume (V) =Area x Length = [{(Pi/4) x Dia x Dia} x L]
 Density of Steel=7850 kg/ cub meter 
Weight = Volume x Density 
= {(3.14/4) x D x D x1) x7850} (if D is in mm & for 1 meter length)
 = ((3.14/4) x D x D x1x7850)/ (1000×1000)
 = D^2/162.27 kg Wt of bar for 1m
= (D^2/162) kg (where D in mm) 
Some Examples:- 
6mm = 0.222Kg/m                  20mm = 2.466 Kg/m 
 8mm = 0.395 Kg /m              25mm = 3.853 Kg/m 
10mm = 0.616 Kg/m              32mm = 6.313 Kg/m 
12mm = 0.888 Kg/m              40mm = 9.865 Kg/m
16mm = 1.578 Kg/m          
STANDARD CONVERSION:
01. 1 RM =3.28 Rft 
02. 1 Inch =2.54 cm 
03. 1 Feet =12.00 Inch 
04. 1 Feet =0.3048m 
05. 1 Meter= 3.2808 ft 
06. 1 Sqm= 10.76 Sft 05. 1 cum =35.32 Cft
 07. 1 sft =0.09Sqm 
08. 1 Cft =0.028 Cum 
09. 1 cum =1000.00 Litre 
10. 1Gallon =4.81 Litres 
11. Link 8″ = 200mm 
12. 1 Cent= 435.60 Sft
 13. 1 Acre=100cent = 0.04 Hectare 
14. 1 Hectare= 2.47 Acres= (10000 m2)  
Site Engineers Must Know About Reinforcement and Steel Bars
  • Hook for stirrups is 9D for one side
  • No. of stirrups = (clear span/Spanning) + 1
  • For Cantilever anchorage length for main steel is 69D
  • “L” for column main rod in footing is minimum of 300mm
  • Chairs of minimum 12 mm diameter bars should be used.
  • Minimum diameter of dowel bars should be 12 mm
  • Lap slices should not be used for bar larger than 36 mm.
  • In steel reinforcement binding wire required is 8 kg per MT.
  • Lapping is not allowed for the bars having diameters more than 36 mm.
  • Minimum number of bars for a square column is 4 and for circular column are 6.
  • Longitudinal reinforcement should not be less than 0.8% and more than 6% of gross C/S.
  • Weight of rod per meter length = d2/162 where d is the diameter in mm
  • All reinforcement shall be free from mill scales, loose rust & coats of paints, oil or any other substances.
  • Main bars in the slabs shall not be less than 8 mm (HYSD) or 10 mm (Plain bars) and the distributors not less than 8 mm and not more than 1/8 of slab thickness.
In Case of spacing of Bars
Provided the diameter of the bar, if the diameter of the bar is equal.
Provide the diameter of larger bar, if the diameter is unequal.
NUMBER OF BRICKS IN 1 CUM:
  • The Standard size of the 1st class brick is 190mmx 90mm x90mm and motor joint should be
    10mm thick So size of brick with motor=200 x 100 x 100. 
  • Volume of 1st class brick = 0.19 x 0.09 X 0.09 =0.001539 cu.m
  •  Volume of 1st class brick with motor =0.2 x 0.1 x0.1=0.002 cu.m 
  • No. on bricks per 1cu.m= 1/volume of 1st class brick with motor =1/0.002 = 500 no’s of bricks 
DEVELOPMENT LENGTH: 
01. Compression 38d
02. Tension 47 & 60d

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