This question may sometimes cross our minds when we see earthworks in the field or in the laboratory. Small volume soil samples compacted in the laboratory are used as a reference or comparison for soil compaction in the field with much larger volumes.Compaction is a process or effort made to compact the soil grains. The aim is to obtain the maximum dry unit weight and the optimum percentage of moisture content with a certain energy. The result of compaction is called density, which depends on the type of soil, moisture content, and energy used. These factors are very closely related to obtain optimal density in the laboratory and in the field.The benefits of this compaction include increasing soil strength, reducing settlement when the soil is loaded, reducing soil permeability, and also reducing swelling and shrinkage in clay soils.
In the Laboratory
By using certain rules or standards, a number of soil samples (± 60 kg) for compaction are taken from the quarry per certain volume or cubication range. Then the sample is taken to the laboratory, if the sample is still too wet it will be dried in the sun first to reduce and reduce the water content (sun dried or in another equivalent way).After that the sample was divided into 5 parts. Each section will be added to the water content based on the planned water content that has been calculated and prepared with a certain percentage. Then each part is compacted with a proctor, either standard or modified. Then weighing and checking the water content.The results of this compaction, namely the dry unit weight and moisture content are plotted onto the graph as well as the ZAVL line. From the graph it can be seen and drawn a line showing the maximum dry unit weight and optimum moisture content
In the field
Soil from the quarry whose samples have been tested for compaction in the laboratory is laid out in the field with a certain thickness. Then trial and error was carried out on the stretch using a field compaction tool. For example, a field compaction tool uses a vibro roller, so how many passes are needed to achieve the desired density.
One of the density values ??in the field is obtained by a combination of the sandcone test and the speedy test. The density value in the field will be compared with the density value in the laboratory to produce a density percentage in the field. Furthermore, the percentage of field density will be adjusted to the specifications needed according to the function of the land.
