Young's Modulus of Normal-Weight Concrete
| Value | 2.5e10 Pa |
| Status | Measured: ± 5,000,000,000 Pa (0.2 relative) |
| Source | ACI 318, Building Code Requirements for Structural Concrete |
| Categories | Material PropertiesEngineering & Trade |
| microbar | 250,000,000,000 μbar |
| barye | 250,000,000,000 Ba |
| millitorr | 187,515,420,000 mTorr |
| pascal | 25,000,000,000 Pa |
| millimeter of water column | 2,549,290,500 mmH₂O |
| pound per square foot | 522,135,860 lb/ft² |
| centimeter of water column | 254,929,050 cmH₂O |
| hectopascal | 250,000,000 hPa |
| millibar | 250,000,000 mbar |
| torr | 187,515,420 Torr |
| millimeter of mercury | 187,515,390 mmHg |
| inch of water column | 100,365,770 in w.g. |
| kilopascal | 25,000,000 kPa |
| foot of water column | 8,363,814.1 ft H₂O |
| inch of mercury | 7,382,495.8 inHg |
| pound per square inch | 3,625,943.4 psi |
| meter of water column | 2,549,290.5 m H₂O |
| decibar | 2,500,000 dbar |
| kilogram-force per square centimeter | 254,929.05 kgf/cm² |
| bar | 250,000 bar |
| atmosphere | 246,730.82 atm |
| megapascal | 25,000 MPa |
| kip per square inch | 3,625.9434 ksi |
| gigapascal | 25 GPa |
| million pounds per square inch | 3.6259434 Mpsi |
Learning zone
Concrete has no true Young's modulus: its stress-strain curve bends from the first increment of load, so codes define a secant modulus to about 45 % of f'c and then estimate it from compressive strength. ACI 318 gives Ec = 4700√f'c in MPa (57 000√f'c in psi), which puts 28 MPa concrete at roughly 25 GPa — about an eighth of steel. Note the square root: doubling the strength of the mix raises stiffness by only 40 %.
The scatter is large and honest. Measured moduli for a given strength routinely fall ±20 % around the formula because aggregate stiffness dominates and aggregate is a local material; limestone, granite and river gravel mixes at the same f'c differ markedly. Lightweight concrete is far softer still. Worse, this is only the short-term modulus: creep under sustained load can multiply long-term deflection by two or three, which is why deflection checks use a reduced effective modulus or an explicit creep coefficient, and why cracked-section properties, not gross Ig, govern serviceability.