Name: wood drying for stronger construction
Uploaded: 2024-09-12T16:16:32.000Z
Duration: 1 min 15 s
Channel: JoVE

フローリングに使用される未加工の木材を考えてみましょう—水分が蒸発すると木材が収縮し、床の接合部に隙間ができます。
木材は水分を吸収すると膨潤し、乾燥すると収縮します。
周囲の空気と一致する木材の水分量は、平衡含水率として知られています。
調味料は、建設後の木材の収縮を防ぎ、構造的な損傷や建築構造の美的損傷を回避します。
風乾とは、木材をゆるく積み上げ、地面から適度に持ち上げ、風通しがきちんと離しておき、曲がりにくく整列させる調味料の方法です。各杭は、防水屋根の下で雨や雪から保護されています。
調味料は窯乾燥によっても行われ、そこでは木材は風乾のように窯に並べて味付けされます。
標準的なフレーミング材は、安定性のために19%の水分まで乾燥されます。収縮抑制のため、構造用木材を15%まで乾燥させます。
味付けされた木材には歪みが見られ、これは木の中の木材の元の位置によって異なります。

木材の乾燥

木材の乾燥は、木材が建築に使用された後に将来の収縮、構造上の損傷、または美観上の問題を防ぐために、木材内の水分含有量を減らして安定させることを目的とした重要なプロセスです。木材は水分を吸収すると自然に膨張し、乾燥すると収縮します。

平衡水分含有量を達成することが乾燥の目標です。これは、木材の水分含有量が周囲の環境の水分レベルに合わせて安定するポイントです。適切な乾燥により、建設後に木材が収縮せず、構造の完全性と外観が維持されます。

木材を乾燥するには、主に自然乾燥と窯乾燥の2つの方法があります。自然乾燥では、木材を層状に緩く積み重ね、地面から十分な間隔を置いて空気の循環を確保し、防水屋根で湿気から保護します。この方法では、乾燥時に木材が反らないように木材を揃えます。

一方、窯乾燥は、制御された環境内で乾燥プロセスを加速し、窯内で空気乾燥と同様に木材を配置します。標準的なフレーム材は、安定性を確保するために通常19パーセントの水分含有量まで乾燥されますが、構造材は収縮を効果的に制御するために15パーセントの水分含有量まで乾燥される場合があります。

乾燥した木材は、木の中での木材の元の位置に応じて歪みが生じる場合があります。これらの乾燥方法は、木材を建築の様々な用途に準備し、耐久性と長寿命を確保するために不可欠です。

フローリングに使用される未加工の木材を考えてみましょう—水分が蒸発すると木材が収縮し、床の接合部に隙間ができます。
木。。。

Education

JoVE Core

Civil Engineering

土木工学

Unit 1

ユニット1

Wood

KEY TERMS AND CONCEPTS

主要用語と概念

Seasoning of Wood

wood drying for stronger construction

Seasoning of wood is the drying process used to lower and stabilize moisture content before wood is used in construction. Fresh wood can swell when it takes in moisture and contract as it dries. Seasoning helps reduce that movement so the wood stays more stable after it is built into a structure.

The main goal is to reach equilibrium moisture content. This is the point where the wood’s moisture level matches the moisture in the surrounding environment. When wood is seasoned properly, it is less likely to shrink after construction and cause structural damage or changes in appearance.

There are two common methods of seasoning wood: air drying and kiln drying. In air drying, lumber is stacked loosely in layers, raised off the ground, and spaced to allow good air circulation. A waterproof roof protects the stack from moisture, and the arrangement helps the wood dry without warping.

Kiln drying speeds up the process in a controlled setting called a kiln. The wood is arranged in a similar way to air drying, but the environment is managed more closely. Standard framing lumber is often dried to about 19 percent moisture content, while structural lumber may be dried to about 15 percent to better control shrinkage.

Seasoned lumber can still show some distortions. These changes depend on the wood’s original position in the tree. Seasoning prepares lumber for use in construction and helps improve durability and long-term performance.

Wood Drying for Stronger Construction

introduction to wood

Wood Structure and Uses in Building

Wood is a construction material made from trees. A tree trunk has several layers. The outside is a protective layer of dead bark. Under that is living bark, then the cambium, then sapwood. As sapwood matures, it becomes heartwood. The pith sits at the center of the trunk. The age of a tree can be read from its growth rings. These rings are concentric bands seen in a trunk cross-section. Wood strength also depends on grain. Grain refers to elongated, tubular cells that run along the length of...

softwoods and hardwoods

Wood Grain in Softwoods and Hardwoods

Softwoods and hardwoods come from different kinds of trees, and their leaf structures and cell makeup help explain how they are used. Softwoods come from cone-bearing trees with needle-like leaves. Hardwoods usually come from trees that shed broad leaves seasonally. Softwoods are made mostly of long cells called tracheids and a smaller number of rays, which are radial cells. This simpler structure gives softwoods a rougher grain. Because of this, they are often used in construction for...

lumber

Lumber Cutting Methods

Lumber is made from logs that are harvested, debarked, and processed into long pieces with a rectangular cross-section. The process starts when an automated saw slices a log into slabs. Those slabs then move on a conveyor belt to smaller saws, where they are cut into square-edged pieces of specific widths. Freshly cut lumber usually has rough surfaces. Its dimensions may also vary slightly from one end to the other. The way wood is cut affects both the lumber’s appearance and how it is used. <br...

structural properties and dimensions of lumber

structural-properties-and-dimensions-of-lumber

Wood Strength Tests and Lumber Sizes

Wood strength depends on how its fibers are aligned along the length of the tree. This alignment gives wood much greater tensile strength along the grain than across it, sometimes up to twenty times higher. Wood also tends to perform better under compression than under tension. Fiber length varies by wood type. Hardwoods have fibers about one twenty-fifth of an inch long. Softwoods have longer fibers that range from one-eighth to one-third of an inch. Laboratory tests help measure how wood...

seasoning of wood

Seasoning of wood is the drying process used to lower and stabilize moisture content before wood is used in construction. Fresh wood can swell when it takes in moisture and contract as it dries. Seasoning helps reduce that movement so the wood stays more stable after it is built into a structure. The main goal is to reach equilibrium moisture content. This is the point where the wood’s moisture level matches the moisture in the surrounding environment. When wood is seasoned properly, it is...

wood surfacing

Wood Surfacing for Smooth, Safe Lumber

Wood surfacing smooths lumber, improves its size accuracy, and makes it safer to handle. It is a key finishing step in woodworking and construction. The process also helps correct small distortions that can form as wood dries. Before surfacing, the wood may be sized slightly larger to account for shrinkage during seasoning, which is the drying stage. A plane, a tool with rotating blades, is used to remove material and smooth the surface. The same tool can also round the edges a little, which...

lumber defects

Common Wood Flaws in Lumber

Lumber defects are flaws in wood that can change both its appearance and its strength. These defects come from tree growth and from the way lumber is processed. Knowing the main defects helps explain why some boards are better for construction and manufacturing than others. Some defects begin in the tree itself. Knots form where branches were once attached to the trunk, and knotholes appear when those knots fall out. Decay and insect damage are also natural defects that can weaken wood and...

wood fasteners

Wood Fastener Types and Uses

Wood fasteners connect parts of a wood structure and help keep members in place. The strength of the connection depends mainly on direct bearing between the wood members. Different fasteners are chosen for different jobs and structural needs. Nails are the most common wood fasteners. They are sharp-pointed metal pins that are driven into wood with a hammer or a mechanical nail gun. Nails come in many diameters, head styles, and lengths. Nailing methods also matter. Face nailing places the...

veneer

How Veneer Is Cut and Used

Veneer is a thin sheet of wood that is usually about one-eighth of an inch thick or less. It is made to show the look of wood while using timber more efficiently. Veneer is common in furniture and other finished wood products. One common way to make veneer is rotary cutting. In this method, a log is mounted in a large lathe and spun against a knife edge. As the knife moves deeper into the turning log, it peels off a continuous strip of wood. This creates rotary-cut veneer. Other veneer...

wood products

Engineered Wood Products in Construction

Engineered wood products are made from wood strands, veneers, lumber, and even waste wood shreds. They are used in both structural and nonstructural building applications. These materials are designed to improve strength, durability, and versatility in modern construction. Glue-laminated wood, or glulam, is made by bonding several smaller pieces of dimensional lumber with adhesive. Cross-laminated timber uses solid lumber panels with layers placed so the grain direction alternates. This layer...

wood panel products

Types of Wood Panels in Construction

Wood panels are common construction materials used for flooring, siding, and roofing. They usually come in standard 4-foot by 8-foot sheets. Their thickness can range from one-quarter of an inch to one and one-eighth inches. Plywood is one of the most familiar wood panels. It is made by gluing thin wood veneers, or layers, under pressure. The outer veneer grain runs lengthwise, while the inner layers run widthwise. Plywood also has an odd number of layers, which helps keep the panel...

key terms and concepts

Learn how seasoning reduces wood moisture, limits shrinkage, and prepares lumber for construction with air drying and kiln drying methods.

Wood Drying for Stronger Construction | JoVE K12

JoVE Core Civil Engineering provides a foundational exploration of essential construction materials in civil engineering, focusing on bricks, stones, steel, wood, and concrete through easy-to-understand animated videos. This collection covers the properties, manufacturing processes, and practical applications of these materials. Additionally, the accompanied science-in-action videos demonstrate the research experiments performed in laboratories.

civil engineering

Wood Drying for Stronger Construction

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