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.
