# Comparison of Field and Laboratory Tests for Soil Suitability Assessment in Raw Earth Construction
## 3 Results and Discussions  
### Field Test Results and Analysis  
Table 2 shows the appearance of the first ten soil specimens obtained with the field tests, namely the ring test, the ribbon test, the dropping ball test, the cigar test, and the pellet test. Scores were assigned to each soil reflecting the comparative observation according to a method like that of [59; 60]. However, some limitations were noted regarding the subjectivity of this evaluation and its accuracy. Indeed, these tests are based on comparison and therefore need to be carried out by experienced professionals. [PERSON] et al. [60] also showed that the correlations are imperfect due to the subjective nature of field test scoring, the limitations of the clay score system in differentiating high plasticity soils, and the variability of field testing conditions. This ring test is simple and can be easily repeated. While the results are qualitative, they are straightforward to differentiate, and the proposed interpretations are clear. To streamline the data processing, each interpretation was assigned a number ranging from 0 to 5. A score of 0 indicates a ring that is impossible to form, while a score of 5 represents a ring easy to form with no cracking. The ring is formed without difficulty for soils 1 and 3, 8, and 10 indicating high clay-sized particle content, cracks and breaks into several pieces for soils 7 and 9, and crumbles for soils 4, 5, and 6, making the ring impossible to form. For the ribbon test, the water content plays a significant role in the progress of the test. However, the test protocol lacks standardized guidelines for determining the optimal water content during the test as it relies on the operator's judgment to achieve a workable consistency. This absence of quantitative moisture control contributes to test variability and makes results more dependent on operator experience. The results of this test are converted to a scale of 0 to 5. A score of 0 indicates that the soil cannot form a coherent ribbon and crumbles immediately, while a score of 5 represents a soil that can be rolled into a ribbon and reformed into a firm, crack-free ball. This test was extremely difficult to achieve on very sandy soil because the ribbon did not form whatever the water content of the soil. A ribbon was easily made from soils 1, 3, and 8 but cracked very quickly for the other soils. \begin{table}
\begin{tabular}{l l l} \hline \hline
**Characteristics of the Soil** & **Field Tests** & **Laboratory Tests** \\ \hline Organic matter content & Smell test [56] & Calcination test [54] \\ \hline \multirow{4}{*}{Granulometry} & Jar test & \multirow{2}{*}{\begin{tabular}{l} Wet sieving and \\ sedimentation [51] \\ \end{tabular} } \\  & Sensory tests: visual, touch, & \\  & sound, bite, separation in the & \\  & palm of the hand, hand & \\  & washing [56] & \\ \hline \multirow{2}{*}{Hydric state} & Texture, Touch & \multirow{2}{*}{Moisture content [58]} \\  & Dropping ball test [41] & \\ \hline \multirow{2}{*}{Plasticity} & Ribbon test [49] & \multirow{2}{*}{\
\begin{tabular}{l} Atterberg limits [52] \\ \end{tabular} } \\  & Ring test & \\ \hline \multirow{2}{*}{Cohesion} & Cigar test & \multirow{2}{*}{
\begin{tabular}{l} Methylene Blue Value \\ test [53] \\ \end{tabular} } \\  & Dropping ball test & \\ \hline \multirow{2}{*}{Swelling-shrinkage} & Pellet test/Dry strength & \\  & test [48]. & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Conducted field and laboratory tests. \begin{table}
\begin{tabular}{c c c c c c} \hline
**Soil Number** & **Ring Test** & **Ribbon Test** & **Dropping Ball** & **Cigar Test** & **Pellet Test** & **Jar Test** (N\({}^{\circ}\) of Layers)** \\ \hline
1 & 5 & 5 & 5 & 37 & Shrinkage: 0 & 1 \\  & 5 & 5 & 5 & 37 & Resistance: 5 & \\ \hline
4 & 5 & 5 &  
For the dropped ball test, the results are highly dependent on the water content of the soil. Therefore, comparing different soils can be challenging, as they do not have uniform plasticity based on their water content.