**6. Ground improvement**

Ground improvement refers to a technology that improves the engineering properties of a mass of treated soil. Usually the properties that are modified are shear strength, stiffness, and permeability. Floor improvement has evolved into a sophisticated tool to support foundations for a variety of structures [35].

#### **6.1 Shallow and deep impaction**

Soil compaction is the process in which pressure is applied to the soil causing concentration as air is exiled from the pores between the soil grains. The compaction is usually the result of heavy machinery compressing the soil [35, 36].

The available techniques can be classified as: Static, Impact, Vibrating, Gyrating, Rolling, and Kneading [35, 36].

#### **6.2 Grout treatment**

A ground remediation operation performed to accomplish one of two things, either to reduce water flow or to improve the properties of the ground by drilling wells in the foundation and injecting material under pressure into the subsurface foundation [35, 37].

Each hole in the filler project is an extension of previous exploration pits and the data collected is used to increase the understanding of subsurface conditions. Injectable materials used for filler range from cementitious plaster materials (particles) to a variety of chemical slurries [37].

Filling foundations in dams and canals to reduce water flow are among the oldest applications of fillers, dating back to the early nineteenth century with plaster curtains in use since the 1890s [37].

#### **6.3 Bentonite suspension**

The different kinds of bentonite are called after their main element, like potassium, sodium, calcium, and aluminum. Bentonite is usually made by weathering volcanic ash, regularly in the presence of water. However, the term bentonite, as well as a similar clay called Tonstein, has been used to describe clay layers of uncertain origin. For industrial purposes, there are two main classes of bentonite: sodium and calcium bentonite. In stratigraphy and tephrochronology, fully demixed ash

layers (weathered igneous glass) are commonly referred to as K-bentonites when the predominant clays are lit. In addition to montmorillonite and the attachment of other common clays that are sometimes prevalent are kaolin. Clays dominated by kaolinite are commonly referred to as tonsteins and are commonly associated with charcoal [35, 38, 39].
