Properties of Concrete

These tables show the structural properties of concrete


Compressive Strength

The most important property of structural concrete is the compressive strength at 28 days (f'c). Common compressive strengths of structural concrete range from 25-85MPa (3500-12000psi). Ultra-high-performance concretes can exceed 85MPa, but they are not widely used on typical structures. Most building codes use the compressive strength as a benchmark and provide empirical relations for stiffness and tensile strength.

Unit Conversion

Concrete properties are usually measured in units of pressure. In Canada, concrete is typically specified in MPa. In the US, it is typically specified in psi or ksi. 1 MPa is approximately 145 psi or 0.145 ksi

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Modulus of Elasticity

The stiffness of concrete material is determined using the Modulus of Elasticity (Young's Modulus). It can be directly measured, but most building codes provide an empirical equation that relates compressive strength to modulus of elasticity.

CSA A23.3

The table below shows the modulus of elasticity for various concretes.

f'c(3300√fc+6900)(yc/2300)1.5
cl. 8.6.2.2
4500√fc
cl. 8.6.2.3
25 MPa24943 MPa = 3618 ksi22500 MPa = 3263 ksi
30 MPa26621 MPa = 3861 ksi24648 MPa = 3575 ksi
35 MPa28165 MPa = 4085 ksi26622 MPa = 3861 ksi
40 MPa29602 MPa = 4293 ksi28460 MPa = 4128 ksi
45 MPa30951 MPa = 4489 ksi30187 MPa = 4378 ksi
50 MPa32228 MPa = 4674 ksi31820 MPa = 4615 ksi
55 MPa33442 MPa = 4850 ksi33373 MPa = 4840 ksi
60 MPa34602 MPa = 5019 ksi34857 MPa = 5056 ksi
65 MPa35714 MPa = 5180 ksi36280 MPa = 5262 ksi
70 MPa36785 MPa = 5335 ksi37650 MPa = 5461 ksi
75 MPa37818 MPa = 5485 ksi38971 MPa = 5652 ksi
80 MPa38817 MPa = 5630 ksi40249 MPa = 5838 ksi
85 MPa39785 MPa = 5770 ksi41488 MPa = 6017 ksi
90 MPa40725 MPa = 5907 ksi42691 MPa = 6192 ksi
Note: Cl. 8.6.2.3 should only be used for f'c less than 45 MPa

ACI 318 and LATBSDC 2020

The table below shows the modulus of elasticity for various concretes.

f'c57000√fc40000√fc+106
4000 psi3605 ksi3530 ksi
4500 psi3824 ksi3683 ksi
5000 psi4031 ksi3828 ksi
5500 psi4227 ksi3966 ksi
6000 psi4415 ksi4098 ksi
6500 psi4595 ksi4225 ksi
7000 psi4769 ksi4347 ksi
7500 psi4936 ksi4464 ksi
8000 psi5098 ksi4578 ksi
8500 psi5255 ksi4688 ksi
9000 psi5407 ksi4795 ksi
9500 psi5556 ksi4899 ksi
10000 psi5700 ksi5000 ksi
10500 psi5841 ksi5099 ksi

Concrete strength guide

  • Low strength (5-20MPa or 1000-3000psi)

    Low strength concrete typically has a strength under 20MPa. It is widely available from ready-mix suppliers and bagged products. Low strength concrete has limited structural value for buildings but may be used in applications such as rat slabs and nonstructural slabs-on-grade, soil enhancement, and small misc footings.

  • Normal strength (25-45MPa or 3500-6500psi)

    Normal strength concrete typically has a strength in the range of 25-45MPa. This concrete is widely available from ready mix suppliers and bagged products. Normal strength concretes are typically used for flatwork such as slabs and footings, as well as beams, columns, and walls in shorter buildings.

  • High strength (45-85MPa or 6500-12000psi)

    High strength concrete typically has a strength in the range of 45-85MPa, although strengths above 65MPa may be difficult to obtain in some markets. This concrete is tyipcally used for vertical elements in tall buildings such as columns and shear walls.

  • Ultra high strength (more than 85MPa or 12000psi)

    Ultra-high performance concrete with strength exceeding 85MPa is typically reserved for special uses and structures. It is not economical to use in most typical buildings.