C30 vs C40

C40 is 1.2 times as stiff as C30. Their densities are about the same. Per unit mass C40 is 1.1 times as stiff. Strength: f_m,k = 30 MPa for C30, f_m,k = 40 MPa for C40.

C30 EN 338:2016 C40 EN 338:2016

Side by side

ratio = C40 / C30 · log scale

Property	C30	C40	Unit	Ratio
E₁ Modulus, direction 1	12	14	GPa	1.17×
E₂ Modulus, direction 2	0.4	0.47	GPa	1.18×
E₃ Modulus, direction 3	0.4	0.47	GPa	1.18×
G₁₂ Shear modulus 1-2	0.75	0.88	GPa	1.17×
G₁₃ Shear modulus 1-3	0.75	0.88	GPa	1.17×
E₀,₀₅ Modulus parallel to grain, 5 % fractile	8	9.4	GPa	1.18×
ρ Density	460	480	kg/m³	1.04×
ρ_k Density, characteristic (5 % fractile)	380	400	kg/m³	1.05×
f_m,k Bending strength	30	40	MPa	1.33×
f_t,0,k Tension parallel to grain	19	26	MPa	1.37×
f_t,90,k Tension perpendicular to grain	0.4	0.4	MPa	1×
f_c,0,k Compression parallel to grain	24	27	MPa	1.12×
f_c,90,k Compression perpendicular to grain	2.7	2.8	MPa	1.04×
f_v,k Shear strength	4	4	MPa	1×
E/ρ Specific stiffness E/ρ · derived	26.09	29.17	MJ/kg	1.12×
c₀ Bar wave speed √(E/ρ) · derived	5108	5401	m/s	1.06×
f/ρ Specific strength f/ρ · derived	65.22	83.33	kJ/kg	1.28×

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.