Compaction energy can be defined as the mechanical energy applied per volume of soil from some mechanical equipment during compaction process. The function of this mechanical energy is to rearrange soil particles, reduce the voids in the soil, increase the soil’s bearing capacity and shear strength and reduce soil permeability. The compaction energy or compactive effort depends on acceleration due to gravity (g), the volume of the mould being used, the height of fall of the rammer, the weight of the rammer, the number of blows and the number of layers receiving each number of blows. The following formula given by (Arcement and Wright, 2001) can be applied to determine the compaction energy.

Where E is the compaction energy, N_{B} is the number of blows per layer, N_{L} is the number of layers, W is the weight of the rammer, H is the height of drop and V is the volume of the mould

Table 1: Details of common compaction methods

Compaction methods | Weight of rammer, W (kg) | Number of blows, N_{B} | Height of drop, H (m) | Number of layers, N_{L} | Volume of mould, V (m^{3}) |

Standard Proctor (ASTM D 698) | 2.5 | 25 | 0.3048 | 3 | 0.000944 |

Modified Proctor (ASTM D 698) | 4.5 | 25 | 0.457 | 5 | 0.000944 |

British Standard Light (BSL) | 2.5 | 27 | 0.3048 | 3 | 0.001 |

British Standard Heavy (BSH) | 4.5 | 27 | 0.457 | 5 | 0.001 |

West African Standard Compaction (WAS) | 4.5 | 10 | 0.457 | 5 | 0.001 |

Applying Equation 1 to Table 1 above, one can determine the compaction energy for the methods. Acceleration due to gravity, g would be a constant value of 9.81 ms^{-2}

Standard Proctor, E = (2.5 x 25 x 0.3048 x 3 x 9.81)/0.000944= 593, 900 J/m^{3}

Modified Proctor, E = (4.5 x 25 x 0.457 x 5 x 9.81)/0.000944 = 2, 671, 380 J/m^{3}

British Standard Light, E = (2.5 x 27 x 0.3048 x 3 x 9.81)/0.001 = 605, 493 J/m^{3}

British Standard Heavy, E = (4.5 x 27 x 0.457 x 5 x 9.81)/0.001 = 2, 723, 526 J/m^{3}

West African Standard, E = (4.5 x 10 x 0.457 x 5 x 9.81)/0.001 = 1, 008, 713 J/m^{3}

Table 2; Summary of Results

Compaction Methods | Compaction Energy (KJ/m^{3}) |

Standard Proctor | 593.9 |

Modified Proctor | 2671.38 |

British Standard Light | 605.493 |

British Standard Heavy | 2723.526 |

West African Standard | 1008.713 |