Lab. Bahan Bangunan - Praktikum Pengujian Berat Jenis dan Kadar Air Kayu

Summary

This video demonstrates the process of testing the moisture content and specific gravity of wood. It covers the step-by-step procedure, including cutting the wood, measuring its volume using mercury displacement, weighing the wood, and drying it in an oven to determine the moisture content. The use of precise instruments like a caliper and balance scale ensures accuracy throughout the testing process. The video highlights how to calculate the moisture content based on the wood's weight before and after drying, offering insights into a critical method for wood analysis.

Takeaways

• 😀 The process involves testing the moisture content and specific gravity of wood using various methods.
• 😀 To perform the moisture content test, a wood sample is cut into a thin piece (1-1.5 cm thick), avoiding the dried edges to ensure accurate results.
• 😀 The volume of the wood sample is determined by displacing mercury, a technique used because wood lacks homogeneity, which makes direct volume calculation difficult.
• 😀 The wood's initial weight is measured using a precision scale before performing any volume displacement.
• 😀 Dimensions of the wood sample are measured (length: 4.3 cm, width: 3.8 cm, height: 4 cm) to help calculate its volume.
• 😀 Mercury is used to displace and measure the volume of the wood by noting the amount of mercury that spills out when the wood is submerged.
• 😀 After measuring the volume, the mercury is weighed to determine the displaced amount, which represents the volume of the wood.
• 😀 To determine the moisture content, the wood is placed in an oven for 24 hours at 110°C, after which it is weighed again to obtain the dry weight.
• 😀 Safety precautions, such as wearing gloves, are emphasized during the experiment, particularly when handling hot objects and mercury.
• 😀 The moisture content is calculated using the formula: (initial weight of wood - dry weight) / dry weight, which gives the percentage of water present in the wood.

Q & A

What is the main purpose of the moisture content and density test for wood in the script?

The main purpose of the test is to measure the moisture content and density of wood in order to determine its water saturation and weight properties, which are important for understanding the wood's quality and usability.

Why is the outer layer of the wood excluded during the moisture test?

The outer layer of the wood is excluded because it tends to dry out, leading to inaccurate moisture measurements. Only the inner part of the wood, which is more representative of the overall moisture content, is tested.

What is the role of mercury in this test procedure?

Mercury is used to replace the volume of the wood in the test. Since wood lacks homogeneity, especially with internal voids or irregularities, mercury's known density allows for precise volume measurement.

How is the volume of the wood determined in this test?

The volume of the wood is determined by submerging the wood in mercury. The amount of mercury displaced by the wood is measured, which corresponds to the wood's volume.

What tools are used to measure the dimensions of the wood in the process?

A caliper is used to measure the length, width, and height of the wood piece to calculate its volume.

How is the initial weight of the wood measured?

The initial weight of the wood is measured using a balance scale with a precision of 0.1 grams. The scale is zeroed before weighing the wood.

Why is the wood placed in an oven for 24 hours, and what is the significance of this step?

The wood is placed in an oven at 110°C for 24 hours to remove its moisture content. This step is crucial to obtain the dry weight of the wood, which is necessary for calculating the moisture content.

What is the purpose of using a desiccator after the wood is removed from the oven?

The desiccator is used to allow the wood to cool down to room temperature before weighing it. This ensures accurate measurements by preventing any external moisture from affecting the weight.

How is the moisture content of the wood calculated?

The moisture content is calculated using the formula: (Initial weight of wood - Dry weight of wood) / Dry weight of wood. This gives the percentage of moisture present in the wood before it was dried.

What are the safety precautions mentioned in the process?

The script advises wearing gloves while handling the wood and equipment, especially when using the oven and desiccator, to ensure safety and prevent burns or exposure to hot surfaces.