WIKA Laboratorium - Pengujian CBR Lapangan (Tanah)

Summary

The video focuses on the field testing of the California Bearing Ratio (CBR) method, commonly used for assessing soil strength and compaction. It details the steps of the testing process, including equipment calibration, loading, and penetration measurements. The video also explains how to calculate the CBR value by analyzing the dropping ring data and interpreting results for both 0.1 and 0.2 penetration levels. Practical application and equipment checks are emphasized, ensuring accurate and reliable results for evaluating the soil’s load-bearing capacity.

Takeaways

• 😀 The CBR (California Bearing Ratio) field test is conducted at SMP 17 38 to assess soil strength for road construction.
• 😀 Equipment used in the test includes a dropping ring, magnetic B, and calibrated tools, ensuring accuracy during measurements.
• 😀 The test involves applying incremental loads to the soil and measuring the penetration at specific intervals like 0.025, 0.05, 0.1, and 0.2 inches.
• 😀 Calibration of all instruments is crucial for obtaining reliable and accurate results during the testing process.
• 😀 Penetration depth measurements at each interval (e.g., 0.025, 0.05, 0.1) are recorded to assess the soil's resistance to load.
• 😀 The test includes multiple cycles, where the operator adjusts the applied load and records the corresponding penetration values.
• 😀 The CBR value is calculated by comparing the actual penetration resistance of the soil to a standard value, expressed as a percentage.
• 😀 Example calculations show that at 0.1 inch penetration, the CBR value is 16.4%, and at 0.2 inch penetration, it is 18.9%.
• 😀 The results are plotted on a graph to visualize the soil's load-bearing capacity, which is essential for designing road pavements.
• 😀 The CBR test is an important method used by engineers to determine suitable materials and construction techniques for road building.

Q & A

What is the main purpose of the CBR field test mentioned in the transcript?

The main purpose of the CBR (California Bearing Ratio) field test is to evaluate the bearing capacity of soil, which is crucial for determining its suitability for road construction and similar infrastructure projects.

What equipment is necessary for conducting a CBR field test?

The necessary equipment for a CBR field test includes a load frame, penetration piston, a dropping mechanism for applying load, and calibration tools to ensure accurate measurements.

What is the process of performing the CBR test in the field?

In the field, the soil sample is compacted in a mold, and the CBR apparatus is set up. A load is applied incrementally to the penetration piston, and the depth of penetration is measured at intervals. The load required for each penetration depth is recorded to calculate the CBR value.

What are the common intervals used for measuring penetration in the CBR test?

Common intervals used in the CBR test for measuring penetration are 0.025 inches, 0.05 inches, and 0.10 inches.

How is the CBR value calculated?

The CBR value is calculated by comparing the load at a specific penetration depth (usually 0.1 inches or 0.2 inches) with the standard load required for crushed stone at the same depth. The formula is: CBR = (Load at penetration / Standard Load) × 100.

Why is the soil sample compacted in the CBR test?

The soil sample is compacted to simulate the conditions that the soil would experience under real field conditions, ensuring that the results are accurate and reflective of the soil's actual performance under load.

What does the graph generated in the CBR test represent?

The graph generated in the CBR test represents the relationship between load (on the vertical axis) and penetration depth (on the horizontal axis), providing a visual representation of the soil's bearing capacity and strength.

What do the CBR values at 0.1 inches and 0.2 inches represent?

The CBR values at 0.1 inches and 0.2 inches represent the soil's resistance to penetration at these specific depths. These values are used to assess the soil's strength and determine its suitability for construction purposes.

How is the final CBR value used in construction?

The final CBR values are compared against design standards to determine the soil's suitability for supporting road construction. Higher CBR values indicate stronger soils, while lower values suggest weaker soils that may require treatment or additional layers for proper support.

What is the significance of the calibration process in the CBR test?

Calibration is crucial to ensure that the testing equipment, including the load frame and penetration piston, is accurate and reliable. Proper calibration guarantees that the CBR test results are precise and valid for assessing soil strength.