The Bricklayers
Christy Hardin, Jacob Loeske, Dwight Johnson, and Jonathan Kolich
Abstract/Summary
We wanted to test bricks of different composition against a real brick. The testing involved a simple compression test of the bricks to failure. Our objective was to make a brick as strong as a real brick. We molded two types of brick of varying textural composition: Two brick of a silt loam soil, two bricks of a shrink-swell clay. The bricks were fired in the oven and then allowed to cool. They were then tested in a compression test to determine the strength. The real brick was the strongest at 60,000lbs then the silt loam at 44,000lbs. The shrink-swell clay brick fell apart easily and was unusable as a real brick.
Introduction
It is known that bricks must have clay to be structurally acceptable. We wanted to test homemade bricks of various textures to determine the correct amount of clay needed to make an acceptable brick. The two textures we used were silt loam (~20% clay, ~60% silt) and clay (~60% clay, ~20% silt). We hypothesized that the clay will make a stronger brick then the silt loam because of its high clay content. The soil colloids should hold the structure together stronger then the silt loam. We are unsure of the affect of the organic matter content in the soils. This can affect the structural properties of the soil, which might affect the strength of the shrink-swell clay.
Material and Methods
· 8"x4"x3.5" wooden frame
· Silt loam (sample from LSU location)
· Shrink swell clay (Gaston)
· Compression Machine (CEBA)
· 10 Qt. Bucket
· Shovel
· Oven and kiln
Procedure
1. Find two different types of soil (clay, silt loam)
2. Make a bold for the bricks using 2x4 glued together for a 8x4x3.5 mold
3. Hold the mold together securely while packing the moist soil into the mold. Keep the soil moist using distilled water, but do not saturate the soil. Fill the mold above the top and scrope off excess soil with a spatula.
4. Carefully remove the mold from the soil by scraping the inner sides with the spatula to separate the soil from the wood mold.
5. Very gently transfer the brick onto a baking tray to be put in the oven.
6. Repeat steps 3-5 for the rest of the bricks.
7. Place the bricks in the oven for two day at 200 degrees Celsius.
8. After initial drying, place the bricks in a kiln and bake for two days at 1000 degree Celsius.
9. Remove bricks from kiln and let cool for 1 day. Be sure to wear protective gloves when handling the bricks.
10. After bricks have been cooled, they can now be tested for compressibility strength using a variable load.
11. Place the first brick in the compression tester with a flat, cast iron plate on both sides of the brick to allow. (See Pictures)
12. Cover the testing area with a screen and wear protective eyewear.
13. Gradually increase the load on the bricks while looking at the gage. When the needle dips suddenly and galls, that is the point of failure. Record the highest point reach by the gage.
14. Repeat steps 11-13 for the others bricks
Result and Conclusion
Compare to our standard, at 2286 PSI, the bricks
made of silt loam withstood more pressure with a mean breaking strength
of 1375 PSI than the shrink-swell clay brick at 169 PSI.
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Our initial hypothesis that the shrink-swell clay would outperform the silt loam brick proved incorrect. We attribute the low mean breaking strength due to the compositional nature of the shrink swell clay; the shrink -swell clay contains a high amount of organic matter, which increases aggregation. Thus, when dried the clay aggregate shrunk leaving large amounts of pore space. Because of this pore space, the brick is easily susceptible to breakage when exposed to pressure. On the other hand, the silt loam's high mean breaking strength can be attributed to little to no organic matter in its composition. In conclusion, we discovered that soil composition plays a major role in a brick's success or its failure.
Appendix A
Shrink-Swell Clay
Brick Silt Loam Brick
Manufactured Brick
Silt Loam Brick
Shrink-Swell Brick
Silt Loam Brick After Test
Silt Loam Brick After Test