Pengujian Hidrometer - Praktikum Survey dan Penyelidikan Geoteknik

Summary

This video presents a detailed procedure for performing a hydrometer test, aimed at determining the grain size distribution of soil, specifically for soils without particles larger than 2mm. The process involves using specific tools such as a hydrometer, thermometer, and various laboratory equipment. The test includes preparing a soil sample, mixing it with a reagent, and observing the soil suspension over time using the hydrometer and thermometer. The final step involves filtering the soil through a 200-mesh sieve. The video provides clear instructions, ensuring accurate and reliable results for soil analysis.

Takeaways

• 😀 The hydrometer test is used to determine the particle size distribution of soil, specifically for fine-grained soils like silt and clay.
• 😀 The test requires various tools and materials such as a hydrometer, thermometer, balance, 1000 cc graduated cylinder, porcelain dish, mixing apparatus, stopwatch, distilled water, and sodium hexametaphosphate reagent.
• 😀 90 grams of soil passing through a number 4 sieve is used in the test.
• 😀 The soil is mixed with 200 ml of distilled water and sodium hexametaphosphate reagent, which is then stirred until homogeneous.
• 😀 The soil and reagent mixture is transferred to a mixer, where it is stirred for approximately 1 minute.
• 😀 After mixing, the suspension is transferred into a 1000 cc graduated cylinder and topped up with distilled water to reach 1000 cc.
• 😀 A second graduated cylinder with distilled water is prepared, along with a hydrometer and thermometer that measures from 0 to 50°C with 0.5°C precision.
• 😀 The hydrometer reading and temperature are taken at 2 minutes after the suspension is in the cylinder, and measurements are repeated at 5 minutes and 30 minutes intervals.
• 😀 After 30 minutes, the hydrometer and thermometer are removed from the first graduated cylinder and placed into the second cylinder containing distilled water for further cleaning.
• 😀 Finally, the soil in the first graduated cylinder is filtered using a 200 mesh sieve to separate the remaining soil particles, and the filtered soil is transferred to a dish for final disposal.

Q & A

What is the main purpose of the hydrometer test?

The main purpose of the hydrometer test is to determine the particle size distribution of soil, especially for soils that do not contain particles larger than 2 mm, such as clay or silt. The test helps distinguish between fine-grained soils like silt and clay.

What materials and equipment are required for the hydrometer test?

The materials and equipment required include a hydrometer, thermometer, balance, 1000 cc graduated cylinder, porcelain dish, suspension stirrer, stopwatch, distilled water, and a reagent (sodium hexametaphosphate).

How much soil should be used in the hydrometer test?

90 grams of soil that passes through a No. 4 sieve should be used for the test.

What is the role of sodium hexametaphosphate in the test?

Sodium hexametaphosphate acts as a dispersing agent to break up soil clumps, ensuring that the soil particles are fully suspended in the water for accurate measurement by the hydrometer.

What is the importance of shaking the mixture in the mixer for one minute?

Shaking the mixture in the mixer for one minute ensures that the soil and reagent are well mixed, facilitating even dispersion of the soil particles for accurate particle size analysis.

How long should the hydrometer and thermometer be left in the suspension for accurate reading?

The hydrometer and thermometer should be left in the suspension for 2 minutes initially, and then readings should be taken at 2 minutes, 5 minutes, and 30 minutes after that.

What is the purpose of using two graduated cylinders in the test?

The two graduated cylinders are used to separately measure the soil suspension and a reference sample of distilled water. This allows for accurate readings of temperature and soil density changes in the suspension.

Why is it important to wash the soil particles through the No. 200 sieve after the test?

Washing the soil particles through the No. 200 sieve ensures that any remaining fine particles are collected, and the water that passes through the sieve is clear. This helps in accurately determining the finer particle content.

What should be done if there are any residues of soil left in the mixer or graduated cylinder?

Any remaining soil in the mixer or graduated cylinder should be washed out with distilled water to ensure no particles are lost, which could affect the accuracy of the test.

What is the final step of the hydrometer test after the soil has been washed?

The final step is to transfer the soil retained on the No. 200 sieve into a porcelain dish and allow it to dry, concluding the hydrometer test.