cee 3400A_LAB5

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Apr 3, 2024

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Georgia Institute of Technology School of Civil and Environmental Engineering Soil Mechanics Laboratory MEMORANDUM To: Ryann Khalil Date: 3/04/2024 From: Fukhraj Khairy Lab Partners: Jordan P.G Benjamin G.M Darien R Subject : Compaction Sample Description Name: Piedmont Soil Source: North Georgia Condition: N/A Visual Classification and Unified Symbol: ML Remarks: N/A Test Procedure The following ASTM standards and procedures were used to determine the maximum dry unit weight of compaction of soils that can be used for the specification of field compaction. Table 1 : ASTM Standards Used In this laboratory, both variants of the Proctor Compaction Test were carried out. The procedures for these tests are essentially the same, but there are a few crucial distinctions. To begin with, secure a sample of Piedmont Soil that has been sieved through Sieve #4. Add water to the soil sample to reach a water content that is approximately 6% below the optimum level, which is around 12% for this type of soil. Make sure the soil is mixed well. To calculate the amount of water needed to achieve the desired water content, use the formula: Mw = ω * Ms, where ω is the water content and Ms is the mass of the soil. Next, measure the combined weight of the Proctor mold and its base plate. Once you have recorded the weight, attach the collar to the mold’s top. start adding the moist soil into the mold.

Take into account that the soil will be compacted, so the amount you need to add depends on the test method: 1. For the Standard Proctor Test, fill the mold to slightly more than half of its height. 2. For the Modified Proctor Test, fill the mold to slightly more than one-third of its height. After the soil is added, gently position the hammer inside the mold and initiate the hammer drops. After loading the soil, cautiously situate the hammer in the mold and start executing the 25 drops. Rotate the mold a little with each hit to guarantee even compaction throughout the sample. Post compaction, redo the steps for reloading the mold, and then compact 25 more times. For the standard method, carry out these steps five times until the mold is filled; for the modified test, also repeat five times. Once compacting concludes, the soil should slightly surpass the mold's rim. Detach the collar and employ a straight edge to scrape off surplus soil. Ascertain the mass of mold, base plate, and compacted soil. Remove the base plate, then employ a jack to eject the compacted soil cylinder. Get a moisture container, find out its mass. Extract a sample from the center of the compacted soil and put it in the container. Jot down the mass of moisture container with the wet soil sample. Add extra water to the primary soil sample aiming to boost the water content by 4%. Redo all the preceding steps. Elevate the water content by an additional 4% twice and reiterate all steps. After completing all experiments (four in total), position the moisture containers in the oven to dry until weight stabilizes. The subsequent day, evaluate the mass of the moisture containers coupled with the dry soil samples. Test Results The equations used to calculate the Actual Water Content and the Dry Unit Weight are shown below. An example calculation is performed for Table A1, Test 1 of the Modified Proctor Test. Mass of Water = (mass of container + wet soil) − (mass of container + dry soil) = 235g – 195.96g = 39.04g Mass of Dry Soil = (mass of container + dry soil) − (mass of container) = 195.96g – 8.5g = 187.46g Water content (%) ?𝑎??? ??????? = ?𝑎?? ?? ?𝑎??? ?𝑎?? ?? ??𝑦 ??𝑖? × 100 = 39.04 187.46 ∗ 100 = 20.83 Sample calcs for Dry unit weight. 𝑉???? = 943.69 ?? ^3 ? ???? = 4343.4 ?? ? ?????? ???? = 5899 ?? ? ??𝑖? = ? ?????? ???? − ? ???? = 5899 − 4343.4 = 1555.6?? ∗ 1??/1000?? = 1.5556??

?? ??𝑖? = ? ??𝑖? ∗ 9.81 ? ? 2 = 1.5556 ∗ 9.81 = 15.26 ? 𝑦 ?𝑢?? = ?? ??𝑖? 𝑉 ???? = 15.26 943.69 = 0.01617 ∗ 1000 = 16.17 𝐾? ? 3 ?𝐶 = 0.2083 𝑦 ? = 𝑦 ?𝑢?? 1 + ?𝐶 = 16.17 1 + 0.2083 = 13.38 ?? ? 3 Dry Unit Weight of Zero Air-Voids Line 𝑦 ??𝑦= 𝑦 𝑚 𝜔+ 1 𝐺 𝑠 = 9.81𝑘𝑁/𝑚^3 0.2083+( 1 2.65 ) =16.75 ?𝑁/?^3 Table 2 : Summarized Test Results STANDARD Mass of Water (g) 39.04 21.32 35.83 73.16 Mass of dry soil (g) 187.46 77.38 113.77 203.94 Water content (%) 20.83 27.55 31.49 35.87 Bulk Unit Weight(kN/m^3) 16.17 18.45 17.86 17.34 Dry unit weight(kN/M^3) 13.38 14.46 13.58 12.76 Zero Air Voids kN/m^3 16.75 15.03 14.17 13.33 MODIFIED Mass of Water (g) 5.29 11.02 17.89 15.66 Mass of dry soil (g) 32.49 44.92 67.88 49.39 Water content (%) 16.28 24.53 26.36 31.71 Bulk Unit Weight(kN/m^3) 20.41 19.41 20 18.32 Dry unit weight(kN/M^3) 17.55 15.59 15.83 13.91 Zero Air Voids kN/m^3 18.16 15.76 15.31 14.13

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The Water Content vs. Compacted Density plot for the Standard compaction Test and the Modified compaction Test is displayed in Figure 1. The figure also displays the Zero Air-Voids line for the saturated soil sample and Modified soil sample. Figure 1 : Compacted Density vs. Water Content of compacted soils. The displays both the Standard Test results and the Modified Test results, as well as the Zero Air-Voids line for the soil Analysis and Discussion 1. How did the use of a heavier hammer and more layers affect the measured maximum dry unit weight and the optimum water content? Why? We played around with two versions of the Proctor Compaction Test – the standard and the modified. The modified test uses this heavyweight hammer and more layers for compacting the soil, and man, it makes a difference. When you put more muscle into it with that heavier hammer, the soil packs in tighter, so the maximum dry unit weight goes up. But here's the kicker, because you're really getting the soil to cozy up to each other, it doesn’t need as much water to reach its best packing form, so the optimum water content takes a dip. It’s kind of like getting more people in a car; if they’re buddies and don’t mind squishing together, you don’t need as much convincing (or in soil’s case, water) to get them all in. 2. If these test results were part of a real geotechnical report for a project, what values of the dry unit weight and the water content would you recommend as specifications? If these test results were part of an actual geotechnical report for a construction project, my recommendations for dry unit weight and water content would depend on the specific

requirements and constraints of the project. However, typically, I would recommend specifying the maximum dry unit weight and the optimum water content derived from the Modified Proctor Test. This is because the Modified Proctor Test generally reflects a higher degree of compaction, which is desirable for providing enhanced stability and support. Concluding Remarks In this lab, ASTM standards were meticulously followed to determine the maximum dry unit weight for soil compaction, which is vital for specifying field compaction requirements. This lab incorporated both the Standard and Modified Proctor Compaction Tests, offering a comprehensive understanding of the compaction characteristics of Piedmont Soil. Our results showed that variations in the compaction effort—in terms of hammer weight and the number of layers—affect soil compaction significantly. The Modified Proctor Test, which employs a heavier hammer and more layers, indicates a higher maximum dry unit weight and a reduced optimum water content when compared to the Standard Proctor Test. This observation is essential for field applications as it implies that increased compaction effort can lead to a denser and more stable soil structure with less water demand, beneficial for supporting structures. From an engineering perspective, the implications of these results are significant. In practical scenarios, the specifications for dry unit weight and water content should reflect the Modified Proctor Test, particularly for projects requiring higher load-bearing capacities and stability. It provides a more conservative and structurally sound basis for design and construction, ensuring that the field compaction meets the stringent requirements necessary for safety and durability. However, it is also critical to acknowledge the limitations of our laboratory work. The controlled environment of a lab differs from field conditions, where variables such as soil heterogeneity, environmental factors, and on-site execution can influence compaction. Therefore, while our laboratory results provide a guideline, field validation and adjustments are necessary to ensure the compaction meets the design specifications. In conclusion, the laboratory work has furnished valuable insights into the compaction properties of Piedmont Soil using both Standard and Modified Proctor Tests. The variations observed between the tests underscore the importance of understanding the impact of compaction effort on soil behavior. This knowledge is instrumental in making informed decisions in the specification of soil compaction for engineering projects, ensuring both efficiency in construction and the longevity of the resulting structures.

References Lambe, W.T., (1991). Soil Testing for Engineers, BiTech, Vancouver. 165 pp. American Society for Testing Materials, (2021), “D1557 - Standard Test Methods for Laboratory Compaction Characteristics of Soil Using Modified Effort”, ASTM International, West Conshohocken, PA. American Society for Testing Materials, (2021), “D698 - Standard Test Methods for Laboratory Compaction Characteristics of Soil Using Standard Effort”, ASTM International, West Conshohocken, PA. Das, B.M, (2000). Fundamentals of Geotechnical Engineering, Brooks/Cole, United States, 593 pp. Author links open overlay panelA. Sridharan a et al. (2003) Swelling behaviour of compacted fine-grained soils , Engineering Geology . Available at: https://www.sciencedirect.com/science/article/abs/pii/S0013795203001613 (Accessed: 20 June 2023). Bridges & Structures U.S. Department of Transportation/Federal Highway Administration . Available at: https://www.fhwa.dot.gov/engineering/geotech/ (Accessed: 21 June 2023). Compaction of fine- grained soils using the Proctor method . Available at: https://prizedwriting.ucdavis.edu/sites/prizedwriting.ucdavis.edu/files/sitewide/pastissues/1 5%E2%80%9316%20KURUMBALAPITIYA.pdf (Accessed: 21 June 2023).

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Appendix Table A1: Complete Data from Standard Test Procedures Volume of mold (cm^3) 943.69 Assume GS 2.65 Mass of mold + base plate (g) 4343.4 Desnsity water 1000 kg/m^3 Test 1 Test 2 Test 3 Test 4 Target Water Content (%) 12 18 22 26 Mass of mold + base plate + compacted sample (g) 5899 6118 6061 6011 Container Label 1 2 3 4 Mass of Container (g) 8.5 8.3 8.5 8.4 Mass of container+ wet soil (g) 235 107 158.1 285.5 Mass of container + dry soil (g) 195.96 85.68 122.27 212.34 Mass of Water (g) 39.04 21.32 35.83 73.16 Mass of dry soil (g) 187.46 77.38 113.77 203.94 Water content (%) 20.83 27.55 31.49 35.87 Bulk Unit Weight(kN/m^3) 16.17 18.45 17.86 17.34 Dry unit weight(kN/M^3) 13.38 14.46 13.58 12.76 Zero Air Voids kN/m^3 16.75 15.03 14.17 13.33 Table A2: Complete Data from Modified Test Procedures Volume of mold (cm^3) 943.69 Mass of mold + base plate (g) 4308.9 Test 1 Test 2 Test 3 Test 4 Target Water Content (%) 10 14 18 22 Mass of mold + base plate + compacted sample (g) 6272 6176 6233 6071 Container Label Newton#1 RubyMax#2 Forsyth#2 Forsyth#1 Mass of Container (g) 8.52 8.46 8.43 8.35 Mass of container+ wet soil (g) 46.3 64.4 94.2 73.4 Mass of container + dry soil (g) 41.01 53.38 76.31 57.74 Mass of Water (g) 5.29 11.02 17.89 15.66 Mass of dry soil (g) 32.49 44.92 67.88 49.39 Water content (%) 16.28 24.53 26.36 31.71 Bulk Unit Weight(kN/m^3) 20.41 19.41 20 18.32 Dry unit weight(kN/M^3) 17.55 15.59 15.83 13.91 Zero Air Voids kN/m^3 18.16 15.76 15.31 14.13

cee 3400A_LAB5

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