LABGEO - Análise granulométrica do solo

Summary

The video script provides a detailed step-by-step explanation of the granulometric analysis process for soil samples. The procedure begins with preparing the soil by sieving and removing clumps, followed by sedimentation using a deflocculant solution. The sample undergoes agitation and measurements are taken using a densimeter and thermometer. After 24 hours, the soil is filtered and dried, and then subjected to fine sieving. The process concludes by weighing the separated soil fractions, which helps in determining the particle size distribution. This analysis is essential for understanding soil composition in various engineering and scientific applications.

Takeaways

• 😀 The granulometric analysis involves determining particle sizes and their respective percentages in the soil sample.
• 😀 A porcelain mortar, Becker funnel, density meter, manual agitator, two 1-liter graduated cylinders, sodium hexametaphosphate solution, metal brush, thermometer, sieve set, and distilled water are needed for the test.
• 😀 The soil sample is placed in the porcelain mortar and ground until homogeneous, with no clods present.
• 😀 The sample is sieved through a 2mm mesh sieve, and any remaining clods are broken down.
• 😀 The next step is sedimentation, where a sodium hexametaphosphate solution is prepared and used to deflocculate the sample.
• 😀 After 12 hours of suspension in the deflocculant solution, the soil sample is transferred to a metallic beaker with chicanas and stirred for 15 minutes.
• 😀 The soil suspension is then transferred to a graduated cylinder, filled with distilled water up to the 1000 ml mark.
• 😀 The density meter and thermometer are placed in the cylinder, and the sample is agitated before taking readings at specified intervals.
• 😀 The density meter stays submerged for 2 minutes before being removed and placed in an auxiliary graduated cylinder with distilled water for a clearer reading.
• 😀 After 24 hours, the soil suspension is passed through a 0.075mm sieve, and the retained material is washed and dried in an oven at 105°C for 24 hours.
• 😀 The final step involves fine sieving the dried material using a series of sieves with various mesh sizes, followed by weighing the material retained in each sieve.

Q & A

What is the purpose of granulometric analysis?

Granulometric analysis is used to determine the sizes of particles and their respective percentages of occurrence in a soil sample.

What materials are required to perform the granulometric analysis?

The materials required include a porcelain mortar, a step funnel, Becker, a densimeter, manual agitator, two 1-liter measuring cylinders, sodium hexametaphosphate solution, a metal brush, thermometer, a set of sieves with metallic frames, distilled water, and a stopwatch.

What is the first step in preparing the soil sample for granulometric analysis?

The first step is to place the soil sample in the porcelain mortar and crush it with the pestle to obtain a homogeneous portion free of clods.

What should be done if clods remain after passing the soil through a 2mm sieve?

If clods remain, the soil should be re-crushed in the mortar until all clods are removed.

What is the role of sodium hexametaphosphate in the analysis?

Sodium hexametaphosphate acts as a deflocculant, which helps disperse the soil particles for better sedimentation analysis.

How is the deflocculant solution prepared for the analysis?

To prepare the deflocculant solution, 45.7 grams of sodium hexametaphosphate are added to 1 liter of distilled water.

What is the purpose of allowing the soil sample to remain in the deflocculant solution for 12 hours?

The soil sample needs to remain in the deflocculant solution for at least 12 hours to ensure complete dispersion of the particles.

What is done after the 12-hour period in the deflocculant solution?

After 12 hours, the soil sample in suspension is transferred to a metallic cup with chicanas and then agitated for 15 minutes.

How are the readings taken during the sedimentation process?

The readings are taken simultaneously using a densimeter and a thermometer at predetermined times. The densimeter remains submerged for two minutes before being removed and placed in another cylinder with distilled water.

What is the purpose of the fine sieving step at the end of the analysis?

The fine sieving step separates the remaining soil particles using a set of sieves with specific openings, allowing for a detailed granulometric distribution of the soil.