Moisture content MC - Revision history

Editor: moved Moisture content to Moisture content MC

2022-10-07T10:11:41Z

moved Moisture content to Moisture content MC

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Revision as of 10:11, 7 October 2022

Editor at 12:36, 18 August 2022

2022-08-18T12:36:59Z

← Older revision		Revision as of 12:36, 18 August 2022
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	With soils, moisture content can be estimated by satellites using microwave remote sensing. This is achieved by contrasting the difference between the dielectric properties of wet and dry soil. Microwave radiation is largely unaffected by the atmosphere and so can penetrate cloud cover. It can also penetrate vegetation through to the ground surface.		With soils, moisture content can be estimated by satellites using microwave remote sensing. This is achieved by contrasting the difference between the dielectric properties of wet and dry soil. Microwave radiation is largely unaffected by the atmosphere and so can penetrate cloud cover. It can also penetrate vegetation through to the ground surface.

−	= Related articles on Designing Buildings ~~Wiki~~ =	+	= Related articles on Designing Buildings =

	* Cavity wall insulation.		* Cavity wall insulation.

Designing Buildings at 07:45, 15 January 2021

2021-01-15T07:45:56Z

← Older revision		Revision as of 07:45, 15 January 2021
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	* Water vapour.		* Water vapour.

−	[[Category:~~Theory~~]] [[Category:~~Design~~]] [[Category:~~Products_/_components~~]] [[Category:~~DCN_Product_Knowledge~~]]	+	[[Category:DCN_Definition]] [[Category:DCN_Guidance]] [[Category:DCN_Product_Knowledge]] [[Category:Theory]] [[Category:Design]] [[Category:Products_/_components]]

Designing Buildings at 11:27, 9 July 2019

2019-07-09T11:27:16Z

← Older revision		Revision as of 11:27, 9 July 2019
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	High moisture content can cause problems, especially when allied with changes in temperature. Saturated brickwork under freezing conditions causes a phenomenon called ‘spalling’ where the face of the brickwork is badly damaged, usually requiring rebuilding or refacing. The mechanism responsible is freezing which causes expansion of the water present in the pores of the material, thereby exerting pressure on the front surface of the brick.		High moisture content can cause problems, especially when allied with changes in temperature. Saturated brickwork under freezing conditions causes a phenomenon called ‘spalling’ where the face of the brickwork is badly damaged, usually requiring rebuilding or refacing. The mechanism responsible is freezing which causes expansion of the water present in the pores of the material, thereby exerting pressure on the front surface of the brick.
		+
		+	Wet rot is a generic name given to a range of conditions that can affect timber where there is the continual presence of moisture, perhaps caused by leaking pipework, poor ventilation (resulting in condensation), rising or penetrating damp and so on. For more information see: Wet rot.
		+
		+	Most moulds require relatively high levels of moisture in order to grow. The majority require an equivalent of at least 70% relative humidity to thrive and most large mould outbreaks in buildings, occur where porous, cellulose-type materials contain persistent liquid water or condensation. For more information see: Mould growth in buildings.
		+
		+	Soils can also change with moisture content. For example, ground heave is the upward movement of the ground usually associated with the expansion of clay soils which swell when wet. As the soil generally cannot expand downwards or sideways, the result is that the exposed upper surface of the soil rises up. For more information see: Ground heave.

	With soils, moisture content can be estimated by satellites using microwave remote sensing. This is achieved by contrasting the difference between the dielectric properties of wet and dry soil. Microwave radiation is largely unaffected by the atmosphere and so can penetrate cloud cover. It can also penetrate vegetation through to the ground surface.		With soils, moisture content can be estimated by satellites using microwave remote sensing. This is achieved by contrasting the difference between the dielectric properties of wet and dry soil. Microwave radiation is largely unaffected by the atmosphere and so can penetrate cloud cover. It can also penetrate vegetation through to the ground surface.
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	* Water vapour.		* Water vapour.

−	[[Category:Theory]] [[Category:Design]] [[Category:Products_/_components]]	+	[[Category:Theory]] [[Category:Design]] [[Category:Products_/_components]] [[Category:DCN_Product_Knowledge]]

Designing Buildings at 11:22, 9 July 2019

2019-07-09T11:22:38Z

Editor at 16:02, 24 June 2019

2019-06-24T16:02:46Z

← Older revision		Revision as of 16:02, 24 June 2019
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	To arrive at the moisture content of a material, the following formula can be used:		To arrive at the moisture content of a material, the following formula can be used:

−	Moisture content (%) = wet mass – dry mass	+	* Moisture content (%) = (wet mass – dry mass) / dry mass
−		+
−	~~Dry~~ mass	+

	Moisture content can also be expressed as a ratio that can range from 0 (completely dry) to a material’s saturation value. Equilibrium moisture content (EMC) is the point where a material neither gains nor loses moisture.		Moisture content can also be expressed as a ratio that can range from 0 (completely dry) to a material’s saturation value. Equilibrium moisture content (EMC) is the point where a material neither gains nor loses moisture.

Editor: Created page with "Moisture content (or water content) is the amount of water or water vapour that is contained in the pores (voids) of a material. It is the percentage by mass of the water present..."

2019-06-24T16:01:53Z

Created page with "Moisture content (or water content) is the amount of water or water vapour that is contained in the pores (voids) of a material. It is the percentage by mass of the water present..."

New page

Moisture content (or water content) is the amount of water or water vapour that is contained in the pores (voids) of a material. It is the percentage by mass of the water present. Moisture content is usually expressed as a percentage of the material’s dry weight and may also be referred to as its porosity. Knowledge of a material’s moisture content is used in various technical and scientific areas. Understanding the moisture content of materials is useful, especially for common materials such as wood, ceramics, soil and rock.

= Calculating moisture content =

To arrive at the moisture content of a material, the following formula can be used:

Moisture content (%) = wet mass – dry mass

Dry mass

Moisture content can also be expressed as a ratio that can range from 0 (completely dry) to a material’s saturation value. Equilibrium moisture content (EMC) is the point where a material neither gains nor loses moisture.

The calculation above is usually used after a sample of the material in question is dried. In most substances, the amount of water present will vary due to weather variables such as relative humidity and temperature. For example, in most cases, including wood, as the humidity increases, so does the moisture content, while a decrease in humidity leads to a decrease in moisture content.

Acceptable moisture levels in wood are typically:

* Wood flooring 6-8%
* Furniture 6-9%
* Construction 9-14%

Materials such as glass, most plastics and steel have no pores and so have almost zero porosity. This means they are literally devoid of having an internal surface area into which moisture can penetrate, be absorbed or be transmitted through.

= Reversible and irreversible moisture content =

Variations in the moisture content of materials can cause movement in buildings. In porous building materials, moisture content changes can cause reversible or irreversible movement.

Irreversible moisture movement is seen, for example, in bricks that have just been manufactured: just out of the kiln, clay bricks will be very dry and will start to absorb moisture immediately causing irreversible expansion. In contract, calcium silicate bricks are cured by an autoclave process using heat and steam; they will be more saturated than normal bricks and, as their moisture content drops to achieve an equilibrium with that of the atmosphere, they will immediately shrink. Both these examples illustrate why some building materials should not be used immediately for building.

Reversible moisture expansion is seen in materials that are part of a building structure. They generally expand when wet and shrink when dry. In doing so, they can have dramatic and unfortunate consequences on a building if their behaviours are not understood and accounted for. They therefore require thoughtful and intelligent detailing e.g movement joints, to maximise the life – and aesthetics – of the construction.

High moisture content can cause problems, especially when allied with large changes in temperature. Saturated brickwork under freezing conditions causes a phenomenon called ‘spalling’ where the face of the brickwork is badly damaged, usually requiring rebuilding or refacing. The mechanism responsible is that freezing causes expansion of the water present in the pores of the material, thereby exerting great pressure behind the front surface of the brick.

With soils, moisture content can be estimated by satellites using microwave remote sensing. This is achieved by contrasting the difference between the dielectric properties of wet and dry soil. Microwave radiation is largely unaffected by the atmosphere and so can penetrate cloud cover. It can also penetrate vegetation through to the ground surface.

= Related articles on Designing Buildings Wiki =

* Cavity wall insulation.
* Condensation.
* Damp.
* Damp proofing.
* Dew point.
* Humidity.
* Insulation.
* Mould growth.
* Types of water.
* Ventilation.
* Wall insulation and moisture risk.
* Water.
* Water vapour.

[[Category:Theory]] [[Category:Design]] [[Category:Products_/_components]]

← Older revision		Revision as of 11:22, 9 July 2019
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−	~~Moisture~~ content (or water content) is the amount of water ~~or water vapour~~ that is contained in the pores (voids) of a material. It is the percentage by mass of the water present~~. Moisture content is usually expressed as a percentage of~~ the material’s dry weight ~~and may also be referred to as its porosity. Knowledge of a material’s moisture content is used in various technical and scientific areas~~. Understanding ~~the~~ moisture content ~~of materials is~~ useful~~, especially~~ for common materials such as wood, ceramics, soil and ~~rock~~.	+	= Introduction =
		+
		+	The term 'moisture content' (or water content) refers to the amount of water that is contained in the pores (voids) of a material. It is usually expressed as the percentage by mass of the water present relative to the material’s dry weight. Understanding moisture content can be useful for a number of common materials such as wood, ceramics, soil and so on.

	= Calculating moisture content =		= Calculating moisture content =
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	* Moisture content (%) = (wet mass – dry mass) / dry mass		* Moisture content (%) = (wet mass – dry mass) / dry mass

−	Moisture content can also be expressed as a ratio that can range from 0 (completely dry) to a material’s saturation value. Equilibrium moisture content (EMC) is the point ~~where~~ a material neither gains nor loses moisture.	+	Moisture content can also be expressed as a ratio that can range from 0 (completely dry) to a material’s saturation value. Equilibrium moisture content (EMC) is the point at which a material neither gains nor loses more moisture.

−	~~The calculation above is usually used after a sample of the material in question is dried.~~ In most substances, the amount of water present will vary due to ~~weather variables~~ such as relative humidity and temperature. For example, in most cases, including wood, as the humidity increases, so does the moisture content, while a decrease in humidity leads to a decrease in moisture content.	+	In most substances, the amount of water present will vary due to conditions such as relative humidity and temperature. For example, in most cases, including wood, as the humidity increases, so does the moisture content, while a decrease in humidity leads to a decrease in moisture content.

	Acceptable moisture levels in wood are typically:		Acceptable moisture levels in wood are typically:
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	Variations in the moisture content of materials can cause movement in buildings. In porous building materials, moisture content changes can cause reversible or irreversible movement.		Variations in the moisture content of materials can cause movement in buildings. In porous building materials, moisture content changes can cause reversible or irreversible movement.

−	Irreversible moisture movement is seen, for example, in bricks that have just been manufactured: just out of the kiln, clay bricks will be very dry and will start to absorb moisture immediately causing irreversible expansion. In ~~contract~~, calcium silicate bricks are cured by an autoclave process using heat and steam; they will be more saturated than normal bricks and, as their moisture content drops to achieve an equilibrium with that of the atmosphere, they will ~~immediately~~ shrink. Both these examples illustrate why some building materials should not be used immediately for building.	+	Irreversible moisture movement is seen, for example, in bricks that have just been manufactured: just out of the kiln, clay bricks will be very dry and will start to absorb moisture immediately causing irreversible expansion. In contrast, calcium silicate bricks are cured by an autoclave process using heat and steam; they will be more saturated than normal bricks and, as their moisture content drops to achieve an equilibrium with that of the atmosphere, they will shrink. Both these examples illustrate why some building materials should not be used immediately for building.

−	Reversible moisture expansion is seen in materials that are part of a building structure. They generally expand when wet and shrink when dry. In doing so, they can have dramatic and unfortunate consequences on a building if their behaviours are not understood and accounted for. They therefore require thoughtful and intelligent detailing e.g movement joints, to maximise the life – and aesthetics – of the construction.	+	Reversible moisture expansion is seen in some materials that are part of a building structure. They generally expand when wet and shrink when dry. In doing so, they can have dramatic and unfortunate consequences on a building if their behaviours are not understood and accounted for. They therefore require thoughtful and intelligent detailing e.g movement joints, to maximise the life – and aesthetics – of the construction.

−	High moisture content can cause problems, especially when allied with ~~large~~ changes in temperature. Saturated brickwork under freezing conditions causes a phenomenon called ‘spalling’ where the face of the brickwork is badly damaged, usually requiring rebuilding or refacing. The mechanism responsible is ~~that~~ freezing causes expansion of the water present in the pores of the material, thereby exerting ~~great~~ pressure ~~behind~~ the front surface of the brick.	+	High moisture content can cause problems, especially when allied with changes in temperature. Saturated brickwork under freezing conditions causes a phenomenon called ‘spalling’ where the face of the brickwork is badly damaged, usually requiring rebuilding or refacing. The mechanism responsible is freezing which causes expansion of the water present in the pores of the material, thereby exerting pressure on the front surface of the brick.

	With soils, moisture content can be estimated by satellites using microwave remote sensing. This is achieved by contrasting the difference between the dielectric properties of wet and dry soil. Microwave radiation is largely unaffected by the atmosphere and so can penetrate cloud cover. It can also penetrate vegetation through to the ground surface.		With soils, moisture content can be estimated by satellites using microwave remote sensing. This is achieved by contrasting the difference between the dielectric properties of wet and dry soil. Microwave radiation is largely unaffected by the atmosphere and so can penetrate cloud cover. It can also penetrate vegetation through to the ground surface.