# Sandy Loam Soil Shear Strength Parameters and Its Colour
## 8 Conclusions  
The main target behind this article is fulfilled, and it shows the ability of relating the shear strength parameters of the tested sandy loam soil to its colour. The shear strength parameters were measured using the direct shear test. The tendency of the cohesion and the internal friction angle plotted points as a function of moisture content is changing in a specified trajectory (curve can be obtained using a trendline fitting the points). With the increase in the moisture content, the colour reflectance of the soil has also shown a clear tendency (curve of specified path fitting the plotted point). By analysing the obtained results, the following tangible results about the soil behaviour (mechanical and colour) can be concluded:  
* When measuring the shear strength of the soil using the direct shear test, it is important to take into consideration the effect of the consolidation load on the result and that it is recognized not just experimentally by comparing obtained results, but also in [PERSON]'s equation (Equation (1)).
* The shear cohesion and the internal friction angle of soil are influenced by the moisture content and that can be recognized in the obtained results and in the soil physical behaviour.
* For the tested sandy loam soil, the shear cohesion increases with the increase in the moisture content reaching a maximum breaking point, and, beyond this point, the shear cohesion tends to have a low value. The internal friction angle of the sandy loam soil decreases with the increase in the moisture, showing the maximum value at ambient conditions (no water added) and low values at high moisture content.
* At high moisture contents, the water films existing between the particles act as lubrication, breaking the cohesive bonds between the particles and decreasing the friction resulting from the contact of the particles.
* The colour reflectance of sandy loam soil decreases with the increase in moisture till reaching a level (at a moisture value), and, beyond this moisture value, the reflectance results are approximately constant.
* Plotting the reflectance at 700 nm will result in a curve equation which is beneficial in finding the moisture if having a given colour reflectance value at 700 nm. Using the obtained moisture value, the shear cohesion and the internal friction angle can be calculated using the curves fitting the plotted points (Figures 5 and 6).
* The results in this article (shear strength parameters and the colour) are of the tested soil type and cannot be generalised. Even though the tested soil is sandy loam soil, it has its mechanical composition (mentioned in the text), and this is a major reason why the results of another sandy loam soil type might be different.  
Writing--original draft, A.E.H.; Writing--review & editing, A.E.E.A.; Supervision, P.K. All authors have read and agreed to the published version of the manuscript.  
This work was also supported by Hungarian University of Agriculture and Life Sciences.  
Not applicable.  
Data Availability Statement: The data presented in this study are available upon request from the corresponding author.  
This work was created within the framework of the \"National Laboratory of Cooperative National Laboratories\" project of the \"Establishment and Complex Development of National Laboratories\" program funded by the National Research, Development and Innovation Office with identification number 2022-2.1.1-NL-2022-00012.  
The authors declare no conflict of interest.