about visual classification and microscopy lab
It is a very important advantage to be able to be able to describe soils accurately and precisely to other engineers. The main goals for the visual classification laboratory are to be able to for describe soils for engineering purposes based on visual, tactile, and olfactory examinations and manual tests. Some of these manual test, which are based on the USCS criteria, include dry strength, dilatancy, toughness, and plasticity. For the microscopy portion of the lab the main goal was to be able to use the microscope and analyze our soil. This lab was the last one to be done in the semester. As an overall goal for this lab, one should be able to go back into our previous labs and see how far one has come in characterizing the soil we have been conducting labs on this entire semester.
methodology
Visual Classification
As a result of having such organic material, it was determined that our soil would be first passed through both a #20 sieve and a #200 sieve. This separated the organic material from our finer sands that were needed in order to visually inspect our soil. While most of the visual classification portion of this lab is based on visual analyze, there are some portions that do require some procedures. These procedures are based on the USCS classification based on the following Visual Identification Criteria or Fine Grained Soils found below.
As a result of having such organic material, it was determined that our soil would be first passed through both a #20 sieve and a #200 sieve. This separated the organic material from our finer sands that were needed in order to visually inspect our soil. While most of the visual classification portion of this lab is based on visual analyze, there are some portions that do require some procedures. These procedures are based on the USCS classification based on the following Visual Identification Criteria or Fine Grained Soils found below.
Microscopy Analysis
Microscopic analysis is an extension of the visual classification lab and is based purely on visual inspection of our soil. Criteria that was considered during our visual inspection were: Variations in soil appearance at different magnifications and differences in various grain sizes due to the addition of water.
Microscopic analysis is an extension of the visual classification lab and is based purely on visual inspection of our soil. Criteria that was considered during our visual inspection were: Variations in soil appearance at different magnifications and differences in various grain sizes due to the addition of water.
Visual classification lab results
Angularity
For this portion of the lab results, we will be discussing the soil collected from a #200 sieve, as shown in figure 2, as this soil provides the best type of soil for this discussion. As can be seen in figure 2, the fine portion of the soil does indeed have some angularity to it, however it is very minimal. Sharp edges are present in what appear to be flakes.
For this portion of the lab results, we will be discussing the soil collected from a #200 sieve, as shown in figure 2, as this soil provides the best type of soil for this discussion. As can be seen in figure 2, the fine portion of the soil does indeed have some angularity to it, however it is very minimal. Sharp edges are present in what appear to be flakes.
Color
With mostly organic material, the color of this sample is a very dark brown as can be seen in figure 1, figure 2, and figure 3. When it becomes wet however, it becomes much darker. This is probably due to fine particles that mix with the water to create a dark mud.
With mostly organic material, the color of this sample is a very dark brown as can be seen in figure 1, figure 2, and figure 3. When it becomes wet however, it becomes much darker. This is probably due to fine particles that mix with the water to create a dark mud.
Odor
Peat material is known to be made up of mostly organic material. With that being said, our soil sample had a very strong organic and earthy odor to it. Almost like the smell right after it rains.
Peat material is known to be made up of mostly organic material. With that being said, our soil sample had a very strong organic and earthy odor to it. Almost like the smell right after it rains.
Range of Particle Sizes and Dispersibility
For this portion of the lab, a stoppered test tube test was performed. The test tube was roughly filled with 1/5 of the way with our soil sample and the remaining 4/5 with water. The test test was then shaken and time was monitored and noted for how long it took for the sample to settle. Particle immediately setting are sand particles. Particles taking roughly five minutes are made up of clays. Particles that float are of organic materials. The results can be seen in figures four, five and six. While looking at figure six, it becomes much easier to distinguish certain particles sizes. It can be noted that the soil sample has very little fine sand particles that sink to the bottom immediately. Roughly speaking, they would make up approximately ten percent of the total sample. The remaining sample floated all to the top. This indicates that the sample is of organic material and is very buoyant. Larger particles like the ones found in figure three, could not be fit into the test tube. The time it took for the particles to fall out of suspension was a minute. While most of the organic matter that floated, floated quite fast, the material that sunk is the one that took the minute to do so.
For this portion of the lab, a stoppered test tube test was performed. The test tube was roughly filled with 1/5 of the way with our soil sample and the remaining 4/5 with water. The test test was then shaken and time was monitored and noted for how long it took for the sample to settle. Particle immediately setting are sand particles. Particles taking roughly five minutes are made up of clays. Particles that float are of organic materials. The results can be seen in figures four, five and six. While looking at figure six, it becomes much easier to distinguish certain particles sizes. It can be noted that the soil sample has very little fine sand particles that sink to the bottom immediately. Roughly speaking, they would make up approximately ten percent of the total sample. The remaining sample floated all to the top. This indicates that the sample is of organic material and is very buoyant. Larger particles like the ones found in figure three, could not be fit into the test tube. The time it took for the particles to fall out of suspension was a minute. While most of the organic matter that floated, floated quite fast, the material that sunk is the one that took the minute to do so.
For this particular soil, one can not perform the following test: dry strength, dilatancy, toughness, or plasticity. As can be seen in table one, above, highly organic soils, such as this one, are readily identified by color, odor, spongy feel, and frequently by fibrous texture.
Comparison of USCS Classification based on Grain Size Distribution versus Visual Classification
This particular soil type is very easily distinguishable by the naked eye. Its very organic color, odor, and dispersibilty make it unique. When comparing it to our classification from the grain size distribution versus visual inspection they are both clearly peat.
Microscopy lab results
Since this soil is highly organic, this portion of the test does not provide as much useful information as it would for other types of soils. Even while looking at it through various magnifications variations do not occur. At the beginning of the lab, we passed our soil through #200 sieve and the #20 sieve, to see the different grain sizes individually. This did not provided much use because of the composition of the soil, with it being organic and all. Furthermore, adding water would also not provide useful as this would just create mud in which the use of the microscope would not help. The soil does have various grain sizes but could not be made out with the use of the microscope but instead with the help of the sieves.