Things that civil engineers need to know

 # Things that civil engineers need to know.

 Basic Knowledge of Civil Engineering.

 Basic Knowledge of Civil Engineering: Topics:

 #Grade of Concrete, #Grade of Steel, #Compression Strength Test, Block, Slump & #Earth Quake.

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 Grade of Concrete:

 Internationally drawing usually does not mention the mixing ratio of concrete, it mentions the grade.  According to this Grade, Ratio is finalized through Trial Basis Mix Design to get the ultimate strength of concrete.  Let us know about different grades of concrete-

  Ordinary Concrete:

 √ M 5 or 5 N / mm 2 or 725 PSI, Ratio 1: 5: 10

 √ M 7.5 or 7.5 N / mm 2 or 1087.5 PSI, Ratio 1: 4: 8

 √ M 10 or 10 N / mm 2 or 1450 PSI, Ratio 1: 3: 6

 √ M 15 or 15 N / mm 2 or 2175 PSI, Ratio 1: 2: 4

 √ M 20 or 20 N / mm 2 or 2900 PSI, Ratio 1: 1.5: 3

 Standard Concrete:

 √ M 25 or 25 N / mm 2 or 3525 PSI, Ratio 1: 1: 2

 √ M 30 or 30 N / mm 2 or 4350 PSI, Mix Design [1: 0.75: 1.5]

 35 M 35 or 35 N / mm 2 or 5075 PSI, Mix Design [1: 0.5: 1]

 40 M 40 or 40 N / mm 2 or 5800 PSI, Mix Design [1: 0.25: 0.5]

 Note: [1M equals 145 PSI, M25 to M70 Mix Design required]

 In concrete fine aggregate or sand 1.5 to 2 times course aggregate or coating is given and 70% of course aggregate will be 20 mm down graded and 30% will be 12 mm down graded.

 In case of Standard Graded Concrete, 350-400 kg of Cement is used for each Cum of Concrete, as well as Admixture.  The water cement ratio ranges from 0.42 to 0.45, but can never exceed 0.5.

 Gradation of Rebar:

 What is meant by 500W TMT Bar?  Let's find out what it really is.

 500W or 500MPA refers to its Yield Strength, which means that such steel is able to carry 72500 PSI Stress safely within the elastic range.

 Here W means weldable or weldability of steel, meaning it is weldable material, there are many metals in the world like cast iron which cannot be given Joint.

 TMT stands for Thermo Mechanically Treated.  In a word, TMT bar is a High-Strength Reinforcement created by the combination of Thermo Mechanically process.

 Note: Remember 1W is equal to 1Mpa or 145 Psi, that means 500W = 500x145 Psi = 72500 Psi = 72.5 Ksi or 72 Grade.

 Similarly 400W = 400x145 Psi = 58000 Psi = 58 Ksi or 60 Grade Rod, and 275W = 40 Grade Rebar.

  Compressive Strength Test:

 Concrete's compressive strength test is usually done in two ways.

 √ Cylinder Test, Module Size 4 ”x8” or 6 ”x12”

 Ube Cube Test, Module Size 6 ”x6” x6 ”

 Remember that concrete tests are usually of 3, 7, 14, 21 & 28 days.  So let's find out how much strength the concrete gains in how many days.

 Age vs Strength percent

 1 day vs 16%

 3 days vs 40%

 7 days vs 65%

 14 days vs 90%

 28 days vs 99%

 Note: [Various studies have shown that Cube Test gives 15% to 20% more results than Cylinder Test, so Cylinder Test is better than Cube Test for safety reasons.

 Block by Cement Sand Mortar:

 The block is essential for the protection of the clear cover of the RCC member, it must be remembered that the strength of the block must be equal to the design strength of the concrete.  Some instructions for the block.

 The ratio of that block will be 1: 1 [Cement: Sand], 100% Sylhet Sand should be used.

 Curing should be done for at least 7 days.

 Note: In order to keep the placement of the block correct during casting, some # 24 SWG ​​G.I Wire should be inserted inside the block so that the blocks can be tied with rods.

 Moreover, there are very high quality Ready Made Blocks available in the market now, which can be used to get rid of this problem very easily.

 Slump Test of Concrete:

 Slamps are tested to verify the viability of freshly mixed concrete.  Just as adding more water to the concrete mix can lead to segregation, giving less than required can lead to voids, none of which are good for concrete.

 There are basically three types of slamps:

 (i) True Slump

 (ii) Shear Slump

 (iii) Collapse Slump

 There is also another type of slump called Zero Slump.

 Range of Slump:

 (i) Very Low Slump [0-25 mm], it is usually of Dry Mix Type which is used as concrete of road, where vibrating is done with the help of machine.

 (ii) Low Slump [25-50 mm], which is used in the construction of foundation or bridge deck or casing with thick concrete or light reinforcement, where vibrating is done with the help of hand operated vibrator machine.

 (iii) Medium Slump [50-100 mm], usually RCC beams, slabs, concrete slaps prepared for walls are 50-100 mm.  It is vibrated manually or with the help of vibrator machine.

 (iv) High Slump [100-150 mm], usually RCC Column, Retaining Wall concrete slamp is above 100mm.  Especially in structures like Pile, Pier where there is no opportunity to use vibrator machine, the quality of concrete slaps is usually more than 140-150.

 Note: [Admixture must be used to maintain the work ability / Density / Consistency of the concrete as it increases the quality of the slamp by increasing the water in High Slump concrete.]

 At the end of the day let's find out about the intensity and effect of Earth Quake;  Richter scale level vs intensity

 1.  Richter scale scale 0-1.9 - Mechanical or Instrumental.

 2.  Richter scale level 2-2.9 - Very Minor.

 3.  Richter scale

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