Name: stopping white salt crystals on masonry
Uploaded: 2024-09-12T16:16:29.000Z
Duration: 1 min 25 s
Channel: JoVE

エフロレッセンスは、レンガ、石、またはコンクリートの石積みの表面に、結晶性の粉末パッチとして現れ、多くの場合、色は白です。
水が石積みの表面に浸透すると、石積みユニットまたはモルタルに存在する水溶性アルカリ塩が水に溶けます。
最終的に、この水は地表に移動して蒸発し、石積みの表面に塩の堆積物を残します。
工事完了直後に発生する白華は、水とブラシできれいにすることができます。
白華は再び現れるかもしれませんが、雨のような天然の物質は塩の堆積物を洗い流すことができ、時間の経過とともに、塩が石積みから徐々に浸出するにつれて白華は減少します。
数年後に建物の石積みの壁に現れるエフロレッセンスは、最近水が壁に浸透し始めたことを示しています。
漏れの原因を是正することで、エフロレッセンスのさらなる発生を抑制します。
エフロレッセンスを防ぐために、水溶性塩を含まない石積みユニットとモルタルを使用し、石積み壁への水の侵入を最小限に抑えます。
壁は、適切な屋根の排水を提供するか、外部の湿気の侵入を防ぎながら水蒸気の外部への移動を可能にする防水バリアを適用することで保護できます。

石積みの白華

Efflorescence in Masonry

石積み壁の白華は、石積みまたはモルタル内の水溶性塩が原因で、ふわふわした結晶性の粉末で、多くの場合は白色です。水が石積みに浸透すると、これらの塩が溶解して表面に浮き上がり、水分が蒸発するとそこに堆積します。

初期の白華は建設後によく見られ、水とブラシで掃除できますが、場合によっては、雨などの自然要因にさらされると石積み表面から塩が浸出するため、白華が再び現れ、時間の経過とともに徐々に減少することがあります。ただし、建設完了後数年経って石積み表面に白華が現れた場合は、新しい水漏れがあることを示しています。このような場合は、水漏れの原因を特定して修復する必要があります。

白華は、可溶性塩が含まれていないことが検証されている石積みを使用し、清潔なモルタル成分を使用することで防止できます。石積み表面への水の浸入を最小限に抑えることも、白華の発生を抑えます。これは、屋根の排水を十分に確保し、可能な限り屋根の張り出し部分を保護することを通じて行われます。また、水蒸気の外方への移動を妨げることなく湿気の浸入を防ぐコーティングを壁に塗布することで、白華の発生を防止します。場合によっては、中空壁構造が固体壁構造よりも適しており、湿気の浸入を更に防げることがあります。

エフロレッセンスは、レンガ、石、またはコンクリートの石積みの表面に、結晶性の粉末パッチとして現れ、多くの場合、色は白です。
水が浸透すると...

Education

JoVE Core

Civil Engineering

土木工学

Unit 1

ユニット1

Masonry

組積造

KEY TERMS AND CONCEPTS

主要用語と概念

stopping white salt crystals on masonry

Efflorescence is the white, fluffy crystal layer that can form on masonry walls. It happens when water-soluble salts in brick, stone, concrete, or mortar are dissolved by water and carried to the surface. When the water evaporates, the salts are left behind as a powdery deposit.

New efflorescence is often seen soon after construction. In many cases, it can be cleaned with water and a brush. It may also fade over time as rain leaches salts out of the masonry surface. If efflorescence appears years after a building is finished, it often points to a new water leak that should be found and repaired.

Efflorescence can be reduced by choosing masonry units that have been tested for low soluble salts and by using clean mortar ingredients. Limiting water intrusion also helps. Good roof drainage, roof overhangs where possible, and wall coatings that block moisture but still let water vapor escape can all lower the risk. In some buildings, cavity wall construction gives extra protection against moisture compared with solid wall construction.

Stopping White Salt Crystals on Masonry

composite masonry walls

Bonding and Materials in Composite Masonry

Composite masonry walls use two or more wythes, or vertical layers, of masonry to form one unified wall. The wythes may use the same material or different masonry materials. They are joined to work together as a single structure. These wythes can be bonded in several ways. Builders may use mortar-filled collar joints, grouted spaces, or rigid metal ties with reinforcement. Masonry header units can also connect the layers, but this method is rare. Metal ties are often preferred because they...

masonry cavity walls

Masonry Cavity Walls and Moisture Control

Masonry cavity walls use two wythes, or layers, with a hollow space between them. The outer and inner wythes are linked only by corrosion-resistant metal ties. This design helps manage water and improve wall performance. When rainwater passes through the outer wythe, it moves down through the cavity. Flashing catches the water and directs it toward weep holes, where it can leave the wall. The inner wythe often has damp-proofing on the cavity side. This layer also works as an air barrier. The...

masonry loadbearing walls

How Masonry Walls Support Buildings

Masonry load-bearing walls support floors and roofs and carry those loads down to the foundation. They are built from brick, stone, or concrete masonry units. These walls rely on compressive strength, which means they can resist pushes from above very well. Masonry walls may be reinforced or unreinforced, depending on the building needs. They carry dead loads and live loads while using working stresses that stay below the materials' ultimate strength. That safety margin helps the structure...

masonry curtain walls

Masonry Curtain Walls and Support Systems

Masonry curtain walls use brick or stone veneer as an exterior cladding system. The veneer is supported by the building structure, so the wall can be both attractive and functional. Two main construction methods are used for these walls. One method builds the masonry units in place through traditional layering. The other uses prefabricated panels that are assembled on the ground and then lifted into position. In traditional construction, steel shelf angles attached to the spandrel beam carry...

posttensioned masonry walls

How Masonry Walls Gain Extra Strength

Post-tensioned masonry walls gain extra strength from high-strength steel rods or flexible tendons. These tensioning elements are anchored to the foundation and run vertically through the wall. In some walls, they sit inside the cores of the masonry units. In others, they are placed between the masonry wythes, or layers. The wall is built first with the tensioning elements already in place. After the mortar cures fully, the wall is tightened. Steel rods are tensioned by turning nuts against...

cavity drainage and flashings in masonry walls

cavity-drainage-and-flashings-in-masonry-walls

Moisture Control in Masonry Cavity Walls

Masonry cavity walls use a gap between two wythes, or wall layers, to help control moisture. The cavity is usually at least 2 inches wide, and it may contain insulation. Even with insulation, a clear space of at least 1 inch is kept so water can drain away. Some walls also use a continuous drainage mat to reduce the needed space while still moving moisture out. Weep holes are another key part of cavity drainage. These openings sit at the base of the cavity and let collected water escape. They...

thermal insulation in masonry walls

Masonry Wall Insulation Options

Masonry wall insulation can be placed on the outside, inside the wall, or on the interior surface. The best choice depends on the climate, the building design, and whether the wall is being built new or retrofitted. In hot, dry climates, masonry can help smooth indoor temperatures by absorbing heat during the day and releasing it at night. In many other climates, extra insulation is needed to improve thermal resistance. One common exterior method is an Exterior Insulation and Finish System, or...

expansion and contraction in masonry walls

expansion-and-contraction-in-masonry-walls

Masonry Wall Joints for Temperature and Moisture

Masonry walls change size slightly as temperature and moisture change. Builders account for this movement so the wall does not crack or shift out of place. Thermal movement is usually easy to measure and plan for. Moisture movement is harder to predict. New clay masonry units often absorb water and expand over time in normal outdoor conditions. New concrete masonry units behave differently. They usually shrink as they lose extra moisture gained during production. These opposite changes make...

movement joints in buildings

How Buildings Handle Structural Movement

Buildings are designed to handle movement from temperature changes, moisture changes, and structural deflection. If these changes are ignored, they can cause visible damage or even unsafe conditions. Movement joints give building materials room to move without creating distress. Working joints are the simplest type. They are placed during construction and help materials cope with change as the building goes up. Shingled roofs and wood bevel siding are common examples because they can move with...

types of building separation joints

Building Joints for Movement and Stability

Building separation joints help large or complex buildings move in a controlled way. They split a structure into smaller, separate units. This reduces stress when the building shifts under different forces. The joints are grouped into three main types: volume-change joints, settlement joints, and seismic separation joints. Volume-change joints handle expansion and contraction caused by temperature changes and moisture changes. They are placed where the building mass has discontinuities,...

efflorescence in masonry

Efflorescence is the white, fluffy crystal layer that can form on masonry walls. It happens when water-soluble salts in brick, stone, concrete, or mortar are dissolved by water and carried to the surface. When the water evaporates, the salts are left behind as a powdery deposit. New efflorescence is often seen soon after construction. In many cases, it can be cleaned with water and a brush. It may also fade over time as rain leaches salts out of the masonry surface. If efflorescence appears...

mortar joint deterioration in masonry

Repairing Damaged Mortar Joints in Masonry

Mortar joints in masonry can break down when water collects in them and freezes. The repeated freezing and thawing makes the water expand and shrink. That process creates cracks in the joints and can spread damage over time. As the mortar worsens, pieces may spall, or break off from the joint surface. Loose masonry units can follow, and the wall becomes weaker. Damaged joints also let moisture move into the wall, which adds to the problem. Good construction helps protect mortar joints. Using...

masonry in cold and hot weather conditions

masonry-in-cold-and-hot-weather-conditions

Protecting Mortar During Weather Changes

Masonry work changes in cold and hot weather because mortar must stay at the right temperature and moisture level. If mortar freezes before it cures, its strength and watertightness can drop. For proper hydration and curing, mortar should stay between 60°F and 80°F. When the weather is below 40°F, the water used for mortar must be heated. The water should not exceed 120°F, because very hot water can reduce compressive strength and bond strength. Masonry units and sand should also stay dry and...

masonry paving

Masonry Paving Materials and Base Layers

Masonry paving uses bricks, stones, and concrete masonry units to create durable walking and driving surfaces. These materials are selected for their shape, color, strength, and resistance to abrasion and weathering. Masonry units can be used in different paving setups depending on the site and the load they must carry. Some paving systems are installed dry on a thin sand layer over a gravel base. Others are set in mortar or asphalt on a concrete slab. For areas with heavy vehicular loads, a...

key terms and concepts

Learn why white salt crystals form on masonry walls, how to clean early efflorescence, and how to prevent it with better drainage and moisture control.

Stopping White Salt Crystals on Masonry | 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

Stopping White Salt Crystals on Masonry

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