Thumb Rule In Civil Engineering.

Hello Friends today we are going to know some thumb rule of civil engineering...so lets know about that....

what is the thumb rule?

The rule of thumb is colloquially referred to as a thumb rule. A Thumb Rule is a guideline which provides concise advice on a given subject. It is a general concept that offers specific guidance for executing or approaching a given task. Thumb rules usually evolve as a result of practice and experience rather than a theoretical study

The rule of thumb is colloquially referred to as a thumb rule. A Thumb Rule is a guideline which provides concise advice on a given subject. It is a general concept that offers specific guidance for executing or approaching a given task. Thumb rules usually evolve as a result of practice and experience rather than a theoretical study.

1. Thumb Rule for Concrete Volume

The volume of concrete required = 0.038 m3/square feet area

Example:-   If Plan Area = 40 x 20 = 800 Sq. m. So, for the plan area of 800 Sq. m. the area the total volume of concrete required

= 800 x 0.038m3 = 30.4m3

 

2.Steel Quantity for Slab, Beams, Footings & Column

1. Slab-1% of the total volume of concrete.

2. Beam-2% of the total volume of concrete.

3. Column - 2.5% of the total volume of concrete.

4. Footings-0.8% of the total volume of concrete.

Steel required in residential buildings = 4.5 Kgs-4.75 Kgs/sq. Ft. 

Steel required For Commercial buildings = 5.0 Kgs-5.50 Kgs/Sq. Ft.

 

3. Thumb Rules For Shuttering Work

Shuttering costs are taken as 15-18% of the total construction of the building. Shuttering work is done to bring the concrete in Shape. The Thumb rule to estimate the shuttering required is 6 times the quantity of concrete or 2.4 times of the Plinth area.

For example, the concrete quantity is 0 5m3, then Area of Shuttering is 0 5 x 6 = 3m2 Components of Shuttering

Shuttering Ply Quantity estimation

The Shuttering plate Ply Battens, Nails are components of Shuttering

Suppose, The Shuttering Ply has a length, width & depth of 2.44 x 1.22 x 0.012.

The No of Shuttering Ply Sheets = 0.22 times of Shuttering 

Suppose, the Shuttering Area = 3m 

Then Ply required for shuttering = 0 22 x 3 = 0.66m2

Binding Agents for shuttering

Columns shuttering

Shear wall /Retaining wall 

Props/Jacks

 4.BATTENS QUANTITY CALCULATION

Shuttering Batten usually has a length & width of 75mm x 40mm. 

Batten Quantity 19.82 x No. of Ply Sheets If work requires 25 Ply sheets, the total quantity of Battens are 19.82 x 25 = 495 Battens

Nails & Binding Wire Quantity in Shuttering: Approximately, 75 grams of Nails were used in the shuttering of the 1m2 area.

75gms of Binding wire is used for every 1m2 of Shuttering.

Thumb rule for Shuttering oil estimation:

Shuttering oil is applied on the shuttering plate surface used to de- frame or de-assemble from the concrete easily.

Total required Shuttering oil = 0.065 x Total Area of Shuttering

(or)

For every 15m2 of shuttering 1 liter of shuttering oil is consumed. 

Example:

If, total area of shuttering is 15 m2, then Shuttering oil Consumption

= 0.065 x 15 = 0.975.

  5.Cement, Sand, Coarse Aggregate Quantity Calculations

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

 10 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 (12.28: 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, Water 185-20.5 164 Liters,

Admixture 0.5% is 100ml

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/m3 

Note: Sand = 760 Kg with 2% moisture (170.80+15.20)

M35 (1:1.79: 2.57)

Cement 410 Kg/m3

20 mm Jelly 632 Kg/m3

12.5 mm Jelly 421 Kg/m3 River sand 735 Kg/m3

Total water 200 Kg/m3

Admixture 0.7%

Fresh concrete density: 2400 Kg/m3

 Note sand = 735+ 2%, Water = 200- 14.7 185,30,

Admixture = 0.7%

  6.Thumb Rules  for Brickwork

(A)  Brickwork for 1m3 of  230 mm Brickwork  here Cement Qty in  cum   0.876m3 and 25.4 bags .  

 (B) Brick work of 115 mm Brickwork  here cement quantity in cum  0.218m3 and 6.32 bags.

7.Thumb Rules For Cement Masonry Quantity

CEMENT MASONRY TYPE &MIX    -   CEMENT QTY IN BAGS  -   CEMENT QTY IN KOS

(a) 200mm in Cement Masonry work - Ratio 1:6   -      0.124Bags/m2 -  6.2Kgs/m2

(b)150mm in Cement Masonry work-  Ratio 1:6   -     0.093Bags/m2   - 4.65Kgs/m2

(c)200mm in Cement Masonry work-  Ratio 1:4   -  0.206Bags/m2-  10.3Kgs/m2

(d)150mm in Cement Masonry work - Ratio 1:4   -    0.144 Bags/m2 - 7.2Kgs/m2 

(e)100mm in Cement Masonry work - Ratio 1:4    -    0.103Bags/m2 - 5.15kgs/m2

 8.THUMB RULES PLASTERING QUANTITY

(a)Rough Plastering  0.09 Bags/m2 4.5Kgs/m2

(b)Internal Wall Plastering  @0.09 Bags/m2 or  4.5 Kgs/m2

(c)External Wall plastering   @0.175 Bags/m2 or  8.75 Kgs/m2

  9.Thumb Rule for Concrete Mix Designs

FOR ADDING 4 LITERS OF WATER IN 1CU.M FRESHLY MIXED CONCRETE 

1 The slump value will be increased by 25 mm.

2 The compressive strength of concrete will be decreased by 1.5 to 2.0 N/mm2.

3. The shrinkage potential will be increased by 10%. 4 1/4 bag of cement Will be wasted.

10.Thumb rule to calculate the Concrete Volume with respect to area:

The Concrete Volume of 0,038m3 of concrete is used for each Square Feet of Plan area

Example:-

From below fig: Plan Area 20 x 20 = 400SFT The plan area is 400SFT then the total volume of concrete required = 400 x 0.058m3 15.2 m3

 Thanks and Regards 

 Er. Pawan Kumar

Civilengineermantra.blogspot.com

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