# Soil Spectral Behavior Related to Its Load-Bearing Capacity Based on Moisture Content
## 2 Soil Type Used and the Measuring Techniques  
### Load-Bearing Capacity Measurement (Bevameter Test)  
The Bevameter measurement (see Figure 1a) was made at Hungarian University of Agriculture and Life Sciences [26] using the university's soil type (surrounding the university). The soil tested was the sandy loam soil of mechanical composition: sand (90.5%), silt (3.2%), and clay (6.3%). Since the soil infield is inhomogeneous and anisotropic, it is complicated to study the soil [27; 28; 29]. For simplifying this engineering case (studying the soil's mechanical properties), the soil was sieved to study it as a homogeneous material. Having the soil initially at ambient conditions, holding moisture due to the surrounding humidity, the soil was sieved and prepared in the bin of the Bevameter, with height H\({}_{1}\) = 12 cm and inner diameter D\({}_{1}\) = 22 cm.  
Figure 1: Shows (**a**) the main structure of the Bevameter equipment; (**b**) the plate size (diameter = 20 cm), the soil bin (height = 12 cm, inner diameter = 22 cm), and the soil sample; (**c**) the data logger (Spider8); and (**d**) the CATMAN 4.5 software recording the data (force and displacement as a function of time).  
The moisture analyzer (HE53 230 V) was used to measure the soil's moisture content. It works based on the principle of drying. An amount of soil is placed on the tray inside the moisture analyzer and the heating plates inside the moisture analyzer start to dry the sample until reaching unchangeable soil mass (dry mass).  
The analyzer calculates the moisture percentage by subtracting the remaining mass from the initial mass and the answer is divided by the initial mass (the moisture content obtained is the wet-based result). The moisture analyzer is shown in Figure 2a,b.  
The soil bin, with the soil filled to the height of H\({}_{2}\) = 10 cm, was centered under the pressing plate diameter D\({}_{2}\) = 20 cm of the Bevameter as shown in Figure 1b.  
At the top of the Bevameter plate, there are two sensors; one sensor is used for measuring the vertical displacement (mm) and the other is used for measuring the applied load (Force; Newton is the unit) [26]. The results were transferred to a computer using a data logger (Spider 8) and read through the CATMAN 4.5 software (force-displacement graph as a function of time). The data logger and software used are shown in Figure 1c,d, respectively.  
The first test was carried out on the soil at ambient conditions; the test was repeated on the same soil sample but with an increase in the moisture content. After every measurement, the soil was removed from the bin and placed in a bucket, and water was added to increase the moisture content. The new moisture content was measured by the moisture analyzer. The soil was tested at moisture contents of 1.05%, 3.34%, 4.82%, 6.05%, and 7.63%. These moisture content values were chosen randomly since it is difficult to set precise moisture value in the soil. What is important in the moisture value is its effect on the physical status of the soil; thus, upon adding water to the soil when moisturing it and recognizing a change in the soil behavior (even if a slight change), the moisture was measured by the analyzer and the measurement was carried out on the soil sample (the repeated measurements were on the soil with close moisture values).  
The mass of the soil sample (at every moisture value) and the final height (after being compressed by the plate; H\({}_{3}\)) were measured, knowing that the soil was initially at height  
Figure 2: The moisture analyzer (HE53 230 V) showing the (**a**) mass of a sample and (**b**) percentage of moisture content.  
\(\rm H_{2}\). These values were recorded for calculating the soil density before and after applying the load.