C40 vs C45

C45 is 1.1 times as stiff as C40. Their densities are about the same. Per unit mass they are about equally stiff (29.17 and 30.61 MJ/kg). Strength: f_m,k = 40 MPa for C40, f_m,k = 45 MPa for C45.

C40 EN 338:2016 C45 EN 338:2016

Side by side

ratio = C45 / C40 · log scale

Property	C40	C45	Unit	Ratio
E₁ Modulus, direction 1	14	15	GPa	1.07×
E₂ Modulus, direction 2	0.47	0.5	GPa	1.06×
E₃ Modulus, direction 3	0.47	0.5	GPa	1.06×
G₁₂ Shear modulus 1-2	0.88	0.94	GPa	1.07×
G₁₃ Shear modulus 1-3	0.88	0.94	GPa	1.07×
E₀,₀₅ Modulus parallel to grain, 5 % fractile	9.4	10.1	GPa	1.07×
ρ Density	480	490	kg/m³	1.02×
ρ_k Density, characteristic (5 % fractile)	400	410	kg/m³	1.02×
f_m,k Bending strength	40	45	MPa	1.12×
f_t,0,k Tension parallel to grain	26	30	MPa	1.15×
f_t,90,k Tension perpendicular to grain	0.4	0.4	MPa	1×
f_c,0,k Compression parallel to grain	27	29	MPa	1.07×
f_c,90,k Compression perpendicular to grain	2.8	2.9	MPa	1.04×
f_v,k Shear strength	4	4	MPa	1×
E/ρ Specific stiffness E/ρ · derived	29.17	30.61	MJ/kg	1.05×
c₀ Bar wave speed √(E/ρ) · derived	5401	5533	m/s	1.02×
f/ρ Specific strength f/ρ · derived	83.33	91.84	kJ/kg	1.1×

Values at the first thickness band or product form of each material (EN 338:2016; EN 338:2016). A minimum and a characteristic value are not the same kind of number — read the ratio as a guide. Each material's page lists every band and every source.