Standard Reference Values #civilengineer

 Standard Reference Values

Height of residential building – 3 m

Height of individual storey – 1.5 m

Width of roads – 3 m (typical minimum lane width; arterial roads are wider)

Height of parapet wall – 1 m

Width of staircase in building – 0.9 m (minimum clear width)

Thickness of one brick cement plaster – 12 mm

Density of cement – 1440 kg/m³

Volume of cement per m³ of 1:5 mortar – 0.167 m³

Quantity of cement bags in 1 m³ of 1:5 mortar – 4.18 bags

Bulk density of cement – 1440 kg/m³

Specific gravity of cement – 3.15

Bulk density of fine sand – 1450 kg/m³

Bulk density of coarse sand – 1600 kg/m³

Size of coarse aggregate – 20 mm

Bulk density of aggregate – 1650 kg/m³

Specific gravity of aggregate – 2.6

Water–cement ratio for plain concrete – 0.45–0.6 (acceptable range)

Rate of water absorption for brick – 20%

Porosity of brick – 25%

Crushing strength of brick – >75 kg/cm² (min. for class designation)

Unit weight of mild steel – 7850 kg/m³

Yield strength of mild steel – 250 MPa

Modulus of elasticity of steel – 200 GPa

Poisson’s ratio for steel – 0.3

Ultimate strength of high‐yield steel – 460 MPa

Minimum reinforcement cover in beams – 25 mm

Minimum reinforcement cover in slabs – 20 mm

Minimum reinforcement cover in columns – 40 mm

Minimum reinforcement cover in footings – 75 mm

Maximum diameter of bars in slabs – 8 mm (or ≤ slab thickness/8)

Maximum diameter of bars in beams – 16 mm

Maximum diameter of bars in footings – 20 mm

Clear cover for RCC elements – 20 mm (depends on exposure)

Water–cement ratio for grade M20 concrete – 0.5 (typical) 

Nominal mix ratio for M20 – 1:1.5:3 

Cement content in M20 – ≈330 kg/m³ 

Maximum aggregate size in M20 – 20 mm

Workability (slump) of M20 – 75–100 mm 

Characteristic strength of concrete at 28 days for M20 – 20 MPa

Autoclave efficiency (for AAC blocks) – 70–75%

Compressive strength of AAC blocks – 3.5–7.5 N/mm²

Dry density of AAC blocks – 600–800 kg/m³

Thermal conductivity of AAC – 0.17–0.21 W/m·K

Minimum number of bars used for square column – 4 bars

Minimum number of bars used for circular column – 6 bars

Maximum diameter of bars used in slabs – ≤ (thickness/8)

Maximum diameter of bars used in each bay – 10 mm

Max cover of reinforcement in RCC pile cap – 50 mm

Dimensional tolerance of cube – ±1.25 mm

Final setting time of cement – ≤10 hours

Initial setting time of cement – ≥30 minutes

Standard consistency of cement – 30% water

Specific gravity of PPC – 2.75

Specific gravity of slag – 2.9

Bulk density of PPC – 1120 kg/m³

Bulk density of slag – 1200 kg/m³

Water demand of PPC – 27%

Water demand of slag – 29%

Yield strength of grade M25 steel – 500 MPa

Compressive strength of grade M25 concrete – 25 MPa

Modulus of rupture of grade M25 concrete – 3.5 MPa

Tensile strength of concrete at 28 days – 2.5 MPa

Elastic modulus of concrete – 25 GPa

Poisson’s ratio of concrete – 0.2

Minimum diameter of bars used in T‐beam flange – 12 mm

Minimum diameter of bars used in T‐beam web – 10 mm

Minimum diameter of bars used in stair slab – 8 mm

Minimum diameter of bars used in raft foundation – 12 mm

Minimum diameter of bars used in strip footing – 10 mm

Minimum diameter of bars used in pile – 16 mm

Minimum number of bars used for square column – 4 bars

Minimum number of bars used for circular column – 6 bars

Maximum diameter of bars used in slabs – ≤ (thickness/8)

Maximum diameter of bars used in each bay – 10 mm

Max cover of reinforcement in RCC pile cap – 50 mm

Minimum tensile strength of steel – 415 MPa

Characteristic strength of steel at yield – 460 MPa

Compressive strength of grade M30 concrete – 30 MPa

Flow of concrete mixture – 60–140 mm (flow table)

Final setting time of PPC – 0.5–2 hours

Initial setting time of PPC – 15–30 minutes

Light sand grading zone for RCC – Zone II

Coarse sand grading zone for plaster – Zone I

Flight height of bucket elevator – not specified

Cement content in M20 is typically 310–330 kg/m³ rather than 403 kg/m³ .

Slump for M20 is 75–100 mm, not 25–75 mm .

Maximum diameter in slabs should reference slab thickness (≤ thickness/8) rather than a fixed 8 mm.