Before starting Numerical , Learn these topics.

1 cub.m = 35.31 cub.feet

Density of Cement = 1400kg/cub.m

Density of Sand = 1450 kg/cub.m

Density of Aggregate =1500 kg/cub.m

Best starting the calculation of cement,sand and aggregate, Learn the below table:

Concrete Grade | Mix Ratio (cement : sand : aggregates) | Compressive Strength | |

MPa (N/mm2) | psi | ||

Grades of Concrete | |||

M5 | 1 : 5 : 10 | 5 MPa | 725 psi |

M7.5 | 1 : 4 : 8 | 7.5 MPa | 1087 psi |

M10 | 1 : 3 : 6 | 10 MPa | 1450 psi |

M15 | 1 : 2 : 4 | 15 MPa | 2175 psi |

M20 | 1 : 1.5 : 3 | 20 MPa | 2900 psi |

Standard Grade of Concrete | |||

M25 | 1 : 1 : 2 | 25 MPa | 3625 psi |

M30 | Design Mix | 30 MPa | 4350 psi |

M35 | Design Mix | 35 MPa | 5075 psi |

M40 | Design Mix | 40 MPa | 5800 psi |

M45 | Design Mix | 45 MPa | 6525 psi |

High Strength Concrete Grades | |||

M50 | Design Mix | 50 MPa | 7250 psi |

M55 | Design Mix | 55 MPa | 7975 psi |

M60 | Design Mix | 60 MPa | 8700 psi |

M65 | Design Mix | 65 MPa | 9425 psi |

M70 | Design Mix | 70 MPa | 10150 psi |

*Calculation for 1 cub.m of Concrete*

*Calculation for 1 cub.m of Concrete*

**Note : **

Volume of Dry concrete is 54%-57% of Wet volume of concrete.

i.e. Dry volume of concrete = 1.54 * Wet Volume of concrete

Given,

Wet Volume = * 1 cub.m *

Dry volume = **1.54 cub.m **

( Dry concrete is 54%-57% more because there is loss during preparation and also concrete contracts after drying)

*For M20 Concrete *

*For M20 Concrete*

Cement : sand : aggregate = *1 : 1.5 : 3*

Sum of all ratios = ** 1+1.5+3** =

*5.5**CEMENT*

*CEMENT*

*Quantity of cement =** (cement ratio / Sum of ratios ) * Dry volume*

= (1 / 5.5 ) * 1.54

= *0.28 cub. m*

*Density of cement **= 1440 kg/cub.m*

** Mass of cement **= Volume of cement * Density

= 0.28 * 1440

= *403.2 kg*

We know that each bag of cement is of *50 kg*

** Number of cement Bags** = 403.5/50 =

*8 bags**SAND*

*SAND*

*Quantity of Sand** = (Sand ratio / Sum of ratios ) * Dry volume*

= (1.5 / 5.5 ) * 1.54

= *0.42 cub.m*

Density of Sand = *1450kg/cub.m*

Mass of sand = *0.42 * 1450* = *609 kg*

*AGGREGATE*

*AGGREGATE*

** Quantity of aggregate** = (aggregate ratio / Sum of ratios ) * Dry volume

= ( 3 / 5.5 ) * 1.54

= *0.84 cub. m*

** Density of Aggregate** : 1500 kg/ cub. m

*Mass of Aggregate : 0.84 *1500 = 1260 kg.*