# Comparison of Field and Laboratory Tests for Soil Suitability Assessment in Raw Earth Construction
## 2 Experimental Program
### Testing Methodology
#### 2.2.1 Field Tests  
The field tests are simple tests that can be conducted on-site using common tools. These tests are primarily used to qualitatively assess the properties of soil and determine its suitability for earth construction. Table 1 provides an overview of the expeditious tests conducted as part of the experimental program. Sensory tests allow us to understand the soil using our senses such as sight, touch, hearing, smell, and taste for the bite test [47]. The bite test was ruled out for hygiene reasons and lack of traceability of the soil tested. The dry touch test allows seeing and feeling the size of the grains by manipulating the soil between the fingers and in the palm of the hand. The wet touch test allows us to evaluate the soil's reaction to water. The hearing test consists of taking a handful of soil between both hands and bringing it to our ear while rubbing our hands in circles. The sound of grains against each other provides information about their nature. Very sandy soil produces screeching sounds, while very clayey soil produces a softer sound. Finally, the smell test helps determine the presence of a humus-like odor, indicating the presence of OM in the soil. This test allowed for the exclusion of several soils. Note that the interpretation of these tests is quite subjective [48]. The jar test [49] consists of filling \(\mathbb{V}\) of the volume of a bottle with dry soil. The bottle is filled with water while leaving a little air to mix well. After vigorous stirring, the mixture is then allowed to stand. Over time, soil particles settle in distinct layers according to their size and density. The grains of larger sizes fall first because they are heavier and provide an overview of the particle size distribution of the tested soil. In practice, it is not always easy to identify the different grain sizes. This test provides insight into the uniformity of the soil. If the layers of different grain sizes are difficult to distinguish, the soil is well-graded. Conversely, if the distinct layers of the grains with varying sizes are observed, the soil has a less uniform particle size. The ribbon test [49] consists of making a ball of fine mortar 2 to 3 cm in diameter with a water content allowing it to be shaped without the soil being sticky. The ball is then rolled onto a flat, clean surface until a thin ribbon is gradually obtained and splits when its diameter is 3 mm. Once the ribbon is broken, a pellet is reconstructed and crushed between the thumb and forefinger. The reaction of this crushing ball allows us to evaluate the-clay-sized particle content of the soil. This test closely resembles the protocol for measuring the limit of plasticity. Ultimately, this test allows us to reach the plasticity limit of the soil. The ring test is a test that comes from pedologists [48]. This test was included because its interpretation proposes a correspondence between qualitative results and quantitative clay-sized particle content. This test consists of moistening the soil to kneading. Fine soil is rolled into a sausage shape with a diameter of 5 to 10 mm, and then a ring is made with it. If the prepared sausage is impossible to form, then the soil contains less than 10% clay, if it forms but cracks, the soil contains less than 18% clay. If the sausage forms but cracks when the ring is formed, then the soil is believed to contain between 18% and 25% clay. Finally, if the ring forms without cracking, then the soil contains more than 25% clay. The pellet test makes it possible to evaluate the soil's shrinkage and resistance after drying. It requires a ring of approximately 5 cm in diameter and 1 cm high. This ring can be easily created using a plastic PVC pipe and a manual saw. Three rings are filled with soil in a viscous state. Once molded, the soil's pellets are placed into a ventilated space away from direct sunlight. After 8 days of drying, the new diameter of the pellet is measured. This measurement is compared to the original size of the tablet and indicates the shrinkage of the soil.