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According to google.com, it is “the state or quality of a material or membrane that causes it to allow liquids or gases to pass through it.” We are specifically looking at the dynamics of water passing through soil. Water must travel around the particles, for the most part. We need to think about the void spaces in between the individual grains of soil. The larger the spaces in between, the more space water can occupy as it travels through. Picture a jar of marbles, how big are the gaps in between the marbles? Do you think water would be able to move more quickly through a jar of marbles or a jar of sand? We will have to try that this week. In order to analyze a soil, we must quantify its permeability. This is important information for a civil engineer when planning a building site. If they want to build on a hill, they might want to know how the water affects the soil in a storm. There could be some sort of land slide potential. Eduardo explained the theory and some of the math that goes into these tests.

This photo shows some of the data we collected. Let’s go to the beginning of the test. Before running the test we compacted the fuzed quartz sample. The fuzed quartz is one of the transparent soils. It did not become transparent during our test, since water does not have the same index of refraction as the fused quartz. You need to use a different liquid for that. We loaded our permeabilty test device with a sample. We had to measure the mass and volume of the sample.

Before being able to run the test, we had to make sure the sample was saturated. The soil is saturated when all the void spaces are filled with water. This means all the air has left the sample. We watched the exit hose for bubbles. Once the bubbles disappeared, we were ready to run the test. We used a stopwatch to see how much time it took for the tank to empty 200mL. We repeated the test three times to have a reliable test.

We marked lines to show 200mL.

The system is ready to test.This test is ready to go. Russ and I were now comfortable running the permeability tests on our own now. We ran a series of tests on a sandy soil.

I need to go to bed now, but next time I will focus on the mechatronics addition to the soil test. I am still taking guesses on our other mechatronic project. I am not going to tell you what it is, but I will share a photo of the latest version.

I took this picture when I gave up with doing fractions on the basic stamp. It was time to float on to Arduino. What does this thing do? I will snail mail a custom postcard to the person who guesses. Have a magnificent Monday good people!

This work is supported in part by the National Science Foundation under a Research Experience for Teachers (RET) Site grant EEC-0807286. We thank the Mechatronics Lab and the Soil Mechanics Lab for hosting us during our summer research program.