## 2 Materials and Methods
For dry sieving, Equation (4) was used, where the terms had the same meanings as in Equation (3). \[\text{f}=\text{P:M}_{1}\times 100\ [\%] \tag{4}\]  
Determination of crushing strength. This test was performed on the basis of SR EN 1091-1 [18], a European standard presenting the methods for determining the crushing strength of coarse aggregates, defining two methods, respectively: the Los Angeles test (reference method) and the impact crushing test (alternative method). In the case of the research undertaken, the Los Angeles test was applied. The necessary equipment consisted of some sieves as EN 933-2 stated [19], with mesh size according to SR EN 1097-2: 2002 [20], balance, oven sample reduction equipment, and Los Angeles test machine (Waterloo, ON, Canada). The principle of the method was to insert a sample of aggregates into a rotating drum and to roll the aggregates subjected to steel ball tests. In the end, the amount of material retained on the 1.6 mm sieve is determined. Both the sample preparation and working method are described in SR EN 1097-2: 2002 [20]. A temperature-adjustable oven for drying materials (capacity 120 L and ambient temperature range of 5-250 \({}^{\circ}\)C) was used. The Los Angeles coefficient was determined by the relation (5), where \(m\) represents the mass of the rejection on the 1.6 mm mesh screen, expressed in grams. \[\text{LA}=(5000-\text{m})\text{:}50 \tag{5}\]  
Determination of the degree of compaction by using the dynamic plate. The simplest method for determining the degree of compaction of embankments was to determine the dynamic deflection modulus using the dynamic plate. The dynamic modulus of linear deformation is the ratio between the unit compression force applied on the test layer and the corresponding specific deformation. The role of the dynamic plate is to determine, by direct field tests, the linear deformation modulus (dynamic deflection modulus). This method was applied to both non-cohesive and cohesive soils that form part of embankments and foundation or base layers. Thus, the Zorn ZFG 0.2 dynamic board (Zorn Instruments GmbH & Co. KG, Hansestadt Stendal, Germany) is mainly used in the construction of roads or highways, in pavement testing, for testing compaction characteristics in sewers and pillars of foundations. The Zorn ZSG 0.20 dynamic plate that was used, was composed of: the test assembly necessary to produce a defined loading impact (Evd 5-70 MN/m-10 kg), the 300 mm test plate, the ZSG electronic deflectometer 0.2 (Zorn Instruments GmbH & Co. KG, Hansestadt Stendal, Germany), with built-in data memory and digital interface, SD card reader and USB connection, processing software, mini-printer, and batteries. Compared to the usual method, the determination of the linear deformation model based on STAS 8942/3-90 [21] presupposed a very laborious working method, with complex equipment and numerous data readings, the result not being provided immediately (Equation (6)). \[\text{EVD}=22.5\text{:S}\ [\text{MN/m}^{2}] \tag{6}\]  
It should be noted that the other parameters of the plate, namely the plate mass, its diameter, and the height of fall are known and constant, as they are specified in the technical book of the plate. To determine the correspondence between the static strain modulus (EV2) and the dynamic strain modulus (EVD), the Equation (7) was applied:  
\[\text{EV}_{2}=600\times\text{ln}\ \text{f}_{0}\times 300\times(300-\text{EVD}) \ [\text{MN/m}^{2}] \tag{7}\]  
In accordance with the provisions of STAS 8942/3-90, for a compaction degree higher than 99%, the dynamic modulus will be higher than 45 MN/m\({}^{2}\), for a compaction degree higher than 98%, the dynamic modulus will be higher as high as 40 MN/m\({}^{2}\), and for a compaction degree greater than 97%, the dynamic modulus will be greater than 35 MN/m\({}^{2}\). Index of plasticity. Plasticity is the property of cohesive soils to be shaped, keeping the volume and without losing the continuity of the mass.