Some vital short notes for civil engineering students
Least Cover for several RCC members
Slab = 20 mm
Beam = 25 mm
Column = 40 mm
Footing = 50 mm
Exact unit weight of steel
The unit weight concerning steel should be 78.5 KN/m3
Proportion of cement, sand and aggregate for different types of concrete mix grades
M10 = 1:3:6
M15 = 1:2:4
M20 = 1:1.5:3
M25 = 1:1:2
M30 = 1:1:1
Exact unit weight of concrete
It is based on the type of aggregates as well as the amount of voids. With adherence to IS : 456-2000, the unit weight of PCC is 24KN/m3 and RCC is 25KN/m3.
Crank Length In Slab
The crank length should be 0.42D. Here, D denotes depth of slab. It is obtained by deducting bottom cover from top cover i.e. Top Cover – Bottom Cover.
Initial & final setting time of standard cement mix
Initial setting time for standard cement mix should remain approx 30 minutes for different types of cements. For masonry cement it should be 90 minutes. Final setting time of standard cement mix should be 10 hours maximum. For masonry cement, it should not go beyond 24 hours.
Compressive Strength Of Brick
For first class brick, the strength should be 105 kg/cm2
For second class brick, the strength should be 70 kg/cm2
For fire brick, the strength should be 125 kg/cm2
The weight of steel bar in reinforcement
The weight of bar should be kg/m = D2/162.2, here dia means diameter of bar in mm.
Steps for design mix concrete according to IS10262
Target denotes strength fm = fck+1.65 σ, σ = standard deviation
Grade of concrete = N/mm2
Standard deviation for M10, M15 = 3.5
Standard deviation for M20, M25 = 4
Standard deviation for M30 to M50 = 5
Strength of concrete
Flexural strength of concrete (modulus of rupture) fcr = .7√fck
Split tensile strength of concrete (fct) fct = 66fcr
Minimum size of column footing
Minimum size of footing for 9” x 9” column should not be under 1.5 x 1.5 feet
Minimum size of footing for 1’ x 1’ RCC column should not be under 2’ x 2’
Standard Height Of Building Floor
The height should be 11 feet but should not be under 10 feet.