The Elastic modulus of concrete is the coefficient of proportionality between the normal stress and the corresponding relative longitudinal elastic instantaneous deformation at *σ _{1} = 0.3R_{pr}* with axial compression of the samples. (GOST 24452-80 Concretes Russian building standard,

*R*— prismatic strength of concrete) The value of the initial modulus of Elasticity of heavy concrete under compression and tension is given in SP 63.13330.2012 Concrete and reinforced concrete structures. This regulatory document is valid in Russia. In accordance with table 6.11 p. 6.1.15 SP 63.13330.2012 for heavy concrete:

_{pr}Concrete class | The value of the modulus of Elasticity of concrete in compression, Eb, MPa |

B10 | 19000 MPa |

B12,5 | 21500 MPa |

B15 | 24000 MPa |

B20 | 27500 MPa |

B25 | 30000 MPa |

B30 | 32500 MPa |

B35 | 34500 MPa |

The elastic modulus of concrete with prolonged load is determined by the formula:

*E _{b,t}* = Eb /

*(1 + φ*)

_{b,cr}*φ _{b,cr}* — creep coefficient of concrete, taken according to table 6.12 p. 6.1.16

In accordance with table 6.12 p. 6.1.16 SP 63.13330.2012 for heavy concrete B10-B35:

Relative humidity of the ambient air, % | В10 | В15 | В20 | В25 | В30 | В35 |

Above 75 | 2,8 | 2,4 | 2,0 | 1,8 | 1,6 | 1,5 |

40-75 | 3,9 | 3,4 | 2,8 | 2,5 | 2,3 | 2,1 |

Below 40 | 5,6 | 4,8 | 4,0 | 3,6 | 3,2 | 3,0 |