Mechanical Modification
The Mechanical modification process by compaction is aimed to improve coarse-grained cohesionless soil (e.g., loose sand) where rapid densification is achieved by a reduction in air voids by means of a short term external forces. The compaction is performed either by impacts using dynamic compaction (DC) technique or vibrations using vibro compaction (VC) technique.

VC is mainly effective in clean sand below the ground water table where the vibrations will cause local liquefaction around the vibroflot. Whereas, DC can be used in clean to marginal sand. It can also be used in silty or clayey soils above the ground water table where soil is unsaturated or partially saturated.

The selection of the compaction technique depends on the required depth and degree of compaction, gradation of the soils, fines content, degree of saturation, location of the ground water table, risks involved, availability of equipments, time constraint, local experience and the costs. In some projects, a combination of VC and DC is proven to be more cost effective.

Dynamic Compaction (DC)
Dynamic compaction (DC) which use high energy waves from the impact of steel ponder to density the ground was invented and developed by Mr Louis mernard and Mernard Soltraitement international.
The compaction by DC is done systematically usually in a pre-determined grid pattern. It consists of delivering high energy impacts at the ground surface by repeating dropping steel ponder (i.e., 10 t0 40 tons) from heights ranging from 10 to 40m. The spacing between the impact points depends mainly on the depth of treatment, the grain size distribution and its permeability and the location of the ground water level.
This technique induces immediate settlement to the soil and reduces the overall long term settlement. In addition, DC provides a well compacted load bearing platform which helps to transfer the load evenly to the underlying soil and reduces the differential settlement of the treated ground. The bearing capacity and cyclic stress resistance against liquefaction of the ground treated with DC will also be increased.

Vibro Compaction (DC)
Vibro Compaction (VC) involves a process of re-arrangement of soil particles into denser configuration by means of vibrations. Vibrations are created in a horizontal plane providing a lateral compaction effort. Typical equipment used includes an electric or hydraulic vibroflot suspending from a crane with an accompanying generator and a water pump. The vibroflot consists of torpedo shaped horizontally vibrating probe that vibrates at frequencies of 30 to 50 Hz with amplitude of 10 to 40m.

Spacing of compaction points depends upon the soil type, density requirements and the vibroflot characteristics, in most projects, the design and execution of VC works relied on the personal experience of engineers and contractors. These works should be performed by ground improvement specialist companies like Menard Geosystems Sdn Bhd.

Having the expertise of the both DC and VC techniques, Menard Geosystems Sdn. Bhd. is resourceful of combining these two techniques to increase the cost effecting whenever necessary.