**1. Introduction**

Nowadays, globalization generates large amounts of waste that significantly affects the storage areas and the surrounding environment. At the same time, the civil engineering sector is experiencing an exponential development process, which increases the demand for building materials and usable space. Therefore, the need to obtain new materials with lower exploitation costs and natural resources consumption became primary. One solution that has been intensively studied in the last past year, especially in this sector, consists of the development of environmentally friendly materials through a mechanism called geopolymerisation (**Figure 1**). The resulting materials, the geopolymers, consist of a tetrahedra network of aluminates (AlO4) and silicates (SiO4), chemically balanced by alkali ions of K+ , Na+ or Li+ [1]. The geosynthesis manifests itself in nature in great abundance. The Earth consists

**Figure 1.** *Geopolymerisation process.*

of 55% of volume, from siloxo-sialates and sialates, but only 12% pure silica or quartz. The geosynthesis process is based on changes induced in the crystallography of the silica backbone by the aluminum ion (6-fold or 4-fold coordination) and on the chemical changes produced by the same aluminum ion. This geosynthesis process is based on changes in crystallography of the silica backbone by the aluminum ion (VI-fold or IV-fold coordination) and the changes on the chemical part made by the same aluminum ion [2]. In this study, geopolymers refer to alkali activated materials obtained through the geopolymerisation reaction.

Currently, these materials are used in multiple industries, starting from civil engineering applications, up to medicine and spaces industry [3–5]. Therefore, there is high interest in the development of new geopolymers that possess higher properties than conventional materials (such as concretes with ordinary Portland cement or ceramics that use natural resources for their synthesis) [6]. However, the main zone of geopolymeric technology application is in the development of low CO2 construction materials, mainly as an alternative to Portland-based (calcium silicate) cement [7, 8]. Being a performant material is not enough for the market, where it cannot go without a real demand for materials with such characteristics.

Nevertheless, the geopolymers preference over conventional materials is also supported by the soil decontamination potential of these materials, which is mainly related to the possibility to use waste as precursors or as reinforcing elements (**Figure 2**) [3, 9, 10]. Considering these characteristics, i.e. high properties and positive impact on the environment, it can be stated that this cycle is energy saving, natural resources conserver and waste-reducing [11, 12]. Continuing into this idea, using waste it's economically friendly and, first of all, cheaper. Therefore, up to now, waste such as coal ash, red mud, slags, rice husk ash etc. have been investigated as geopolymers precursors [13]. However, the possibility of using waste for geopolymers manufacturing is mainly constrained by the availability of the aluminosilicate source [14, 15]. Based on this limitation, a considerable source for geopolymerisation has been identified, i.e. mine tailings. Moreover, the use of this waste was also encouraged by the fact that mine tailings can be used in blended geopolymers (two or more types of aluminum and silicone rich powders are used for the geopolymers' synthesis). Therefore, when the properties of the final product aren't suitable for the specific application, i.e. when tailored properties are required, usually, the structure of the geopolymers must be reinforced with different types of particles which will contribute to their mechanical characteristics [16–18].

*The Physical and Mechanical Characteristics of Geopolymers Using Mine Tailings as Precursors DOI: http://dx.doi.org/10.5772/intechopen.97807*

**Figure 2.** *The main components of waste-based geopolymers.*

During the last decades, numerous studies have been focused on using mine tailings as precursors or blended component in geopolymers. Therefore, a compressive presentation of the obtained results, i.e. state-of-the-art review, could be a strong encouraging point for further research on this topic and scientific progress. Accordingly, this chapter includes information regarding the availability of this waste and its potential utilization as a raw material in civil engineering applications. Therefore, reports of specific agencies have been summarized and multiple research studies which approach tailing based geopolymers or blended systems are reviewed, and future research objectives have been presented accordingly.
