The following table gives the preferred units for various properties of concrete.

Property                             Units
Cement content……………….kg/m³
Chloride ion diffusion………… m²/s
Compressive strength…………MPa (or N/mm²)
Gas diffusion………………….. m²/s
Grade or Class**………………MPa (or N/mm²)
Half-cell potential………………mV
Modulus of elasticity…………..GPa (or kN/mm²)
Slump…………………………….mm
Tensile strength………………..MPa (or N/mm²)
Thermal conductivity…………..W/m°C or W/mK
Thermal expansion……………..10-6/°C
U value……………………………W/m²°C or W/m²K
Water content…………………..l/m³
Water permeability …………….m/s

** Denotes compressive strength based on cylinders/cubes, e.g. Class 25/30 has a characteristic cylinder strength of 25 MPa (N/mm²) and a characteristic cube strength of 30 MPa (N/mm²)