Compaction

Soil compaction - the foundation of any construction activity

"A structure is only as good as the foundation on which it stands," this principle from structural engineering marks the basis of any construction activity. But those involved in the planning of structures, such as structural engineers and contractors, must not stop at this point. Rather, they must look at the foundation of the foundation - the soil. This is where all loads and forces are transmitted and where they must be absorbed. Therefore, at the beginning of the construction process is always the optimal soil compaction.

Wacker Neuson equipment for soil compaction: a success story

For decades, the name Wacker Neuson has been inextricably linked with soil compaction. In 1930, the Wacker company introduced the first electric vibratory tamper, which at the time revolutionized work on the construction site.

Since then, the Wacker Neuson tamper as well as vibratory plates and rollers have undergone continuous development and today set global standards in terms of performance and environmental friendliness. The key to the high quality and performance of the equipment has always remained the same: Wacker Neuson constantly monitors customer processes in order to respond to changes or new optimization opportunities with innovative approaches.

Why compaction of soils?

Any soil disturbed by removal, excavation or grading should be compacted. With the compaction process, one achieves a change in the introduced, loosened soil material into a uniform, stable and void-free (low porosity) form, with the corresponding improvement in the properties of this soil. Earthwork with the construction material "soil" extends to all parts of civil engineering and plays an important role for road, canal, water, ground, railroad, tunnel and open pit construction. Also in structural, residential and industrial engineering, earthwork measures form the basis, in conjunction with properly executed compaction, for durable, damage-free and stable building structures made of steel, concrete, masonry, wood, etc.

The right choice of vibratory compaction equipment

What factors influence the choice when buying and using a compaction equipment? It is not always easy to give a simple answer to this. Several factors need to be considered. These factors include, for example, soil type, grain shape, grain roughness and grain size distribution. In addition, the site conditions, the specified degree of compaction of the soil to be compacted (Proctor density) and the tender conditions must also be taken into account. The evaluation of the above factors is done for two reasons: 1. to determine which type of machine is best suited for the job, and 2. to be able to recommend which equipment can be used to do the job most economically. Basically, when choosing compaction equipment, a distinction must be made between whether it is to be used in non-cohesive (granular) soils or in cohesive soils.

Noncohesive soils can be compacted most effectively by combining dynamic forces (impact energy) and frequency. Frequency (number of blows/unit of time) causes the soil, and thus the individual grains, to vibrate. The soil vibrates, thus reducing the frictional resistance between the individual soil grains. In this way, the dynamic compaction energy of the compaction equipment can be optimally utilized. The combination of frequency and impact energy reduces the pore spaces and displaces water and air pockets. The bearing density (dry density) of the soil is increased. Vibration increases the depth effect of the impact energy and thus contributes decisively to high efficiency of compaction. In general, very good results are achieved in the compaction of non-cohesive soils with vibratory plates, thanks to the intensive compaction action. In addition to these good compaction results, there is also the high compaction performance, reliability and relatively low cost. Vibratory rollers are used for larger area compaction.

Compaction of cohesive soils is best accomplished by kneading them while pressing or by beating them vigorously. The impact of the percussive work of a vibratory tamper into the cohesive soil causes the individual grains to overcome their adhesion (cementing) to each other (true cohesion). In addition, the grain-to-grain friction is also reduced. Thus, even in these soils, it is achieved that both air and water inclusions are displaced to the surface. This results in a denser bedding. A large stroke height (jump height) at the tamping insert of a vibratory tamper is desirable, as this allows a high single impact work to be achieved, but also to ensure a better advance. A high impact rate in the range of about 700 blows/min produces continuous movement of the soil grains, which is desirable for compaction in both granular and cohesive soils. Universal vibratory rollers with nap or padfoot drums (also called sheepsfoot drums), often used as universal rollers in trenching, are also particularly suitable for heavy cohesive soils, due to the kneading action with simultaneous vibration at high frequency.

Focus of use of vibratory compaction equipment

Vibrating compaction equipment (dynamic compaction) is mainly used in the field of soil and asphalt compaction, although some other applications also arise, such as the vibration of interlocking paving.