C18 vs C27

C27 is 1.3 times as stiff as C18. It is 1.1 times as dense. Per unit mass C27 is 1.1 times as stiff. Strength: f_m,k = 18 MPa for C18, f_m,k = 27 MPa for C27.

C18 EN 338:2016 C27 EN 338:2016

Side by side

ratio = C27 / C18 · log scale

Property	C18	C27	Unit	Ratio
E₁ Modulus, direction 1	9	11.5	GPa	1.28×
E₂ Modulus, direction 2	0.3	0.38	GPa	1.27×
E₃ Modulus, direction 3	0.3	0.38	GPa	1.27×
G₁₂ Shear modulus 1-2	0.56	0.72	GPa	1.29×
G₁₃ Shear modulus 1-3	0.56	0.72	GPa	1.29×
E₀,₀₅ Modulus parallel to grain, 5 % fractile	6	7.7	GPa	1.28×
ρ Density	380	430	kg/m³	1.13×
ρ_k Density, characteristic (5 % fractile)	320	360	kg/m³	1.12×
f_m,k Bending strength	18	27	MPa	1.5×
f_t,0,k Tension parallel to grain	10	16.5	MPa	1.65×
f_t,90,k Tension perpendicular to grain	0.4	0.4	MPa	1×
f_c,0,k Compression parallel to grain	18	22	MPa	1.22×
f_c,90,k Compression perpendicular to grain	2.2	2.5	MPa	1.14×
f_v,k Shear strength	3.4	4	MPa	1.18×
E/ρ Specific stiffness E/ρ · derived	23.68	26.74	MJ/kg	1.13×
c₀ Bar wave speed √(E/ρ) · derived	4867	5171	m/s	1.06×
f/ρ Specific strength f/ρ · derived	47.37	62.79	kJ/kg	1.33×

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.