## 2 Zeolite Materials  
Zeolites are porous, hydrated aluminosilicates with a general formula of M\({}_{\mathrm{x/m}}\)[(AlO\({}_{2}\))\({}_{\mathrm{x}}\)(SiO\({}_{2}\)y)]. H\({}_{2}\)O, where M\({}_{\mathrm{x/m}}\) designates ion-exchangeable cations, and the [(AlO\({}_{2}\))\({}_{\mathrm{x}}\)(SiO\({}_{2}\)y)] unit constitutes the zeolite framework. The connection between the apices of SiO\({}_{4}\) and AlO\({}_{4}\) tetrahedrons using oxygen atoms creates a three-dimensional spatial network in which empty spots are formed as channels and chambers. The negative charge of the crystalline network resulting from substituting Si\({}^{4+}\) with Al\({}^{3+}\) atom in the tetrahedrons is compensated for by exchangeable cations, most often Na\({}^{+}\), K\({}^{+}\), and Ca\({}^{2+}\). The Si/Al ratio in the crystalline framework determines factors such as the mineralogical zeolite type, size of channels and chamber, as well as affecting their ion-exchangeable capabilities and hydrophilic-hydrophobic properties [15].  
A further characteristic property of zeolite group minerals is the presence of water particles in their composition which are bound in a specific way. This is the so-called zeolite water. When heating the mineral to a temperature of approximately 400 \({}^{\circ}\)C, water is constantly released without a change in the zeolite crystal structure. In the WMA technologies the zeolite water is not released in a whole amount because of lower processing temperature. However, the amount of released zeolite water at a particular temperature (e.g., WMA production temperature) can be determined using thermal analysis [16]. Conversely, when the zeolite mineral is present in a humid environment, water particles are also absorbed by its crystalline structure in a continuous manner.  
From the point of view of type, the zeolite mineral group is divided into natural zeolites (formed as a result of geological processes occurring in nature) and synthetic ones (the result of chemical reaction, e.g., sodium silicate, Na\({}_{2}\)SiO\({}_{3}\), sodium aluminate, NaAlO\({}_{2}\), or various types of silicon and aluminium carriers, e.g., fly ashes, loam minerals, perlites at variable temperature, pressure, and reaction time conditions). The natural zeolites which occur the most frequently in nature include clinoptilolite and phillipsite. In the synthetic mineral group, zeolites of the ZSM-5, X, Y, A, and NaP1 types predominate [17; 18].  
In order to accommodate the requirement to reduce mineral-asphalt mix temperatures, various types of zeolite minerals are used. The use of Linde A (LTA) structure-type synthetic zeolites is widely known. Asphalt foaming technologies (Aspha-Min and Advera) are based on additives from this mineral group. Synthetic zeolites produced from Na-P1 (GIS-gismodine zeolite minerals) structure-type fly ashes used in asphalt foaming technology are a heulandites zeolite minerals) is used in WMA [19].  
In order to improve asphalt foaming, it is also possible to use synthetic zeolites activated using a water soaking process [20].  
The crystalline structure and the most important features of several selected zeolite minerals are presented in Table 1[21].  
WMA technology using zeolites gives rise to a decrease in production and compaction temperatures of approximately 30 \({}^{\circ}\)C. It is also possible to use any type of aggregate, including aggregates derived through recycling, and all types of asphalts.