C12/15 vs C70/85

C70/85 is 1.5 times as stiff as C12/15. Their densities are about the same. Per unit mass C70/85 is 1.5 times as stiff. Strength: f_ck = 12 MPa for C12/15, f_ck = 70 MPa for C70/85.

C12/15 EN 1992-1-1 C70/85 EN 1992-1-1

Side by side

ratio = C70/85 / C12/15 · log scale

Property	C12/15	C70/85	Unit	Ratio
E Young's modulus	27	41	GPa	1.52×
G Shear modulus	11.25	17.08	GPa	1.52×
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	70	MPa	5.83×
f_ck,cube Characteristic cube strength	15	85	MPa	5.67×
f_cm Mean cylinder strength	20	78	MPa	3.9×
f_ctm Mean tensile strength	1.6	4.6	MPa	2.88×
f_ctk,0.05 Tensile strength, 5 % fractile	1.1	3.2	MPa	2.91×
f_ctk,0.95 Tensile strength, 95 % fractile	2	6	MPa	3×
ε_c1 Strain at peak stress	1.8	2.7	‰	1.5×
ε_cu1 Ultimate strain	3.5	2.8	‰	0.8×
ε_c2 Strain at peak, parabola–rectangle	2	2.4	‰	1.2×
ε_cu2 Ultimate strain, parabola–rectangle	3.5	2.7	‰	0.771×
n Exponent, parabola–rectangle	2	1.45	–	0.725×
ε_c3 Strain at peak, bilinear	1.75	2	‰	1.14×
ε_cu3 Ultimate strain, bilinear	3.5	2.7	‰	0.771×
E/ρ Specific stiffness E/ρ · derived	11.03	16.75	MJ/kg	1.52×
c₀ Bar wave speed √(E/ρ) · derived	3322	4093	m/s	1.23×
f/ρ Specific strength f/ρ · derived	4.903	28.6	kJ/kg	5.83×

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.