C12/15 vs C55/67

C55/67 is 1.4 times as stiff as C12/15. Their densities are about the same. Per unit mass C55/67 is 1.4 times as stiff. Strength: f_ck = 12 MPa for C12/15, f_ck = 55 MPa for C55/67.

C12/15 EN 1992-1-1 C55/67 EN 1992-1-1

Side by side

ratio = C55/67 / C12/15 · log scale

Property	C12/15	C55/67	Unit	Ratio
E Young's modulus	27	38	GPa	1.41×
G Shear modulus	11.25	15.83	GPa	1.41×
ν Poisson's ratio	0.2	0.2	–	1×
ρ Density	2447	2447	kg/m³	1×
γ Weight density	24	24	kN/m³	1×
α Coefficient of thermal expansion	10	10	10⁻⁶/K	1×
f_ck Characteristic cylinder strength	12	55	MPa	4.58×
f_ck,cube Characteristic cube strength	15	67	MPa	4.47×
f_cm Mean cylinder strength	20	63	MPa	3.15×
f_ctm Mean tensile strength	1.6	4.2	MPa	2.62×
f_ctk,0.05 Tensile strength, 5 % fractile	1.1	3	MPa	2.73×
f_ctk,0.95 Tensile strength, 95 % fractile	2	5.5	MPa	2.75×
ε_c1 Strain at peak stress	1.8	2.5	‰	1.39×
ε_cu1 Ultimate strain	3.5	3.2	‰	0.914×
ε_c2 Strain at peak, parabola–rectangle	2	2.2	‰	1.1×
ε_cu2 Ultimate strain, parabola–rectangle	3.5	3.1	‰	0.886×
n Exponent, parabola–rectangle	2	1.75	–	0.875×
ε_c3 Strain at peak, bilinear	1.75	1.8	‰	1.03×
ε_cu3 Ultimate strain, bilinear	3.5	3.1	‰	0.886×
E/ρ Specific stiffness E/ρ · derived	11.03	15.53	MJ/kg	1.41×
c₀ Bar wave speed √(E/ρ) · derived	3322	3940	m/s	1.19×
f/ρ Specific strength f/ρ · derived	4.903	22.47	kJ/kg	4.58×

Values at the first thickness band or product form of each material (EN 1992-1-1; EN 1992-1-1). 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.