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# Basic Knowledge for Civil Engineers

## Important Points for Civil Site Engineers:

In construction civil engineers doing many activities and facing quick site construction problems for solution of this problem the civil engineers must remember these points, tips and tricks. There are general tips, tricks and tables for civil engineers to remember it and make the construction work easier. If the quality of construction is good. The important and basic knowledge for civil site engineers are given below:

### Basic Points for civil engineer:

The basic knowledge and important points for civil engineer is given below

• Minimum thickness of slab must not be less than 125 mm
• For normal construction the size of coarse aggregate ranges from 10 to 20 mm.
• Lapping of bar must not be used having diameter more than 36 mm
• The height of floor to floor should not be less than 3 m and not more than 4 m.
• Water absorption of bricks should be less than 15 %
• The combination of cement, sand, and coarse aggregate should be according to the design.
• PH value of water should not be less than 6 because below the PH value of 6 it is acidic.
• For calculation of unit weight of steel, the formula is D 2/162.162 in Kg/m. this formula is used when the dia of bar is in mm. while for lb/ft the formula is used D 2/52.9 where dia of steel is in sothar.
• Concrete cover should be sufficient
• The compressive strength of brick is 3.5N/mm.
• Concrete should not be fall from more than 1.5 m height.
• Don’t use over vibrator in concrete.
• For dowel bars the dia of steel should not be less than 12mm.
• For chair bar the dia of steel should not be less than 12 mm
• The formwork should be tight.
• The longitudinal bars should not be less 0.8 % and not more than 6 % of gross c/s.
• The minimum number of bars in circular column is 6 No’s. while in square column the number of bars is 4 No’s.
• Cement should be stored in dry place. It would be raised from the 8 inches above floor level and one (1) foot or 300 mm away from each side of walls. The cement bags should be stocked more than 10 bags in such a manner.
• Electrical conduits shall not run in column or beam.
• In steel construction the binding wire required is 8 Kg per MT.
• The spacing between chair bars should not be more than 1 meter or one chair bar per 1 m2
• The dimension tolerance for cubes +, – 2 mm.
• Earth quick excavation for basement above 3 m should be steeped form
• The water cement ratio must be check.
• Water cement ratio is different for different grade of concrete for example water cement ratio should be 0.45 for M20, M25 and above. 0.50 for M15, M10 and below.
• The cube test should be done for every 30 cubic meter (m3) area.
• The aggregate which are used in concrete must be free from silt, dust and clay or other impurities.
• In aggregate the angular shape is good for construction. In angular shape aggregates it makes the bond perfect and concrete is prepared from it very strong and have high strength.
• In soil filling as per IS code for every 100 square meter (m2) 3 sample for core cutting test should be taken.
• The compaction of concrete should be done properly.
• Concrete should be transport to the shortest route.
• Reinforcement design should be done according to the as per IS codes.

### Density of Materials:

The materials have not same density. the density is different for different materials density of materials is given below:

 S. No Materials Density in Kg / m3 1 water 1000 2 cement 1440 3 Plain cement Concrete 2400 4 Reinforcement concrete 2500 5 Asphalt 721 6 lime 640 7 Lime mortar 1760 8 iron 7850 9 steel 7850 10 Aluminum 2739 11 Glass 2580 12 Zinc 7135 13 Lead 11340 14 Tin 7280 15 Nickle 8908 16 Copper 8940 17 Magnesium 1738 18 Stainless steel 8000 19 Igneous rock 2700 20 Sedimentary rock 2600 21 Metamorphic rock 2700 22 Sandstone 2000 23 Bricks 1500 – 1800 24 Clay soil 1900 25 Bamboo 350 26 Aspen 420 27 Ash (black ) 540 28 Ash ( white) 670 29 Sandy soil 1800 30 Pine 500

### Concrete Cover or Clear Cover to Reinforcement Bar:

Concrete cover is used to protect the rebar against corrosion and to provide resistance against fire. The thickness of concrete is various in different members of structure. The chart or table for concrete cover to reinforcement bar is given:

 S. No Member of structure Concrete cover in (mm) 1 Beam 25 2 Slab 15 3 Stair case 15 4 Column 40 5 Raft foundation Sides 75 6 Footing 75 7 Raft foundation bottom 75 8 Water retaining structures 25 9 Shear wall 25 10 Flat slab 20 11 Grade slab 20 12 Raft foundation top 50 13 Strap beam 50

### Curing Method of Concrete:

The curing method of concrete is given below

• spraying
• ponding
• steam curing
• wet covering
• curing chemicals

### Cube Samples for Different Quantity of Concrete Volume:

Cube sample is used to find the compressive strength of concrete you should find different number of samples for different volume of concrete. The cube samples for different quantity of concrete volume is follow:

 S. No Volume of Concrete Number of samples 1 1 to 5 m3 1 sample 2 6 to 15 m3 2 samples 3 16 to 30 m3 3 samples 4 30 to 50 m3 4 samples 5 50 plus or above 50 m3 5 samples

### Removal of Formwork or De Shuttering Time:

There are different members of formwork such as foundation, beam, column and slabs etc. after poring of concrete the shuttering should be remove after some time the time of de shuttering is given below:

 S. No Members of structure Days 1 Sides of foundation, beam, columns and walls 2 days 2 Sides of slab under 4.5 meter span 7 days 3 Sides of slab above 4.5 meter span 14 days 4 Side of beams and arches up to 6 meter span 14 days 5 Side of beams between 6 meter to 9 meter span 21 days 6 Side of beams and arches above 9 met 28 days

### Weight of Steel Bar per M/Kg:

The weight of steel bar in meter per kilogram is given in table below:

 S. No Dia of bar in (mm) Weight of steel in Kg per meter 1 6 0.22 2 8 0.39 3 10 0.61 4 12 0.88 5 16 1.57 6 20 2.46 7 25 3.85 8 32 6.31 9 40 9.86

Note:

The formula is used in this table is D2/162.162 in Kg/m. this formula is used when the dia of bar is in mm and length of bar in meter.

### Conversion of Units:

The conversion of units is used by every civil engineers on site to make calculation good and quickly. The conversion of units is given below:

 1 secra = 100 ft3 1 pole = 1 perch 1 foot = 12 inches 1 yard = 3 ft 1 foot = 0.304 meter 1 yard = 36 inches 1 foot = 304.8 mm 1 yard = 0.914 meter 1 foot = 30 cm 1 yard = 91.44 centimeter 1 mile = 1.609 km 1 yard = 9144 millimeter 1 millimeter = 0.039 inch 1 karam 5.5 ft 1 inch = 25.4 mm 1 karam = 1.67 meter 1 inch = 2.54 centimeter 1 Marla = 272.72 square feet 1 furlong = 600 ft 1 Marla = 25.10 square meter 1 foot = 0.36 vars 1 kanal = 20 Marla 1 furlong = 40 rods 1 kanal = 502 square meter 1 mile = 8 furlong 1 kanal = 180 square karam 1 mile = 320 rods 1 acre = 160 square rods 1 mile = 800 links 1 acre = 160 poles 1 mile = 80 chains 1 acre = 0.4047 hectare 1 mile = 320 perches 1 Acre = 100 square meter 1 mile = 5280 ft 1 link = 7.92 inches 1 perch = 1 pole 1link = 0.66 foot 1 perch =1 rod 1 link = 0.20 meter 1 perch = 16.5 ft 1 N = 0.101 kg 1 rod = 1 perch 1 kg = 9.8 N 1 perch =25 links 1 ounce = 0.062 lb 1 kg = 2.204 lb 1 kg = 1000 gram 1 ton = 1000 kg 1 gram = 0.001 kg