Air in concrete - Revision history

Editor at 07:34, 23 June 2023

2023-06-23T07:34:03Z

← Older revision		Revision as of 07:34, 23 June 2023
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	* Aerated cellular concrete (ACC)		* Aerated cellular concrete (ACC)
	* Aerated lightweight concrete (ALC)		* Aerated lightweight concrete (ALC)
−	* Foamed concrete	+	* Foamed concrete.
−	* Lightweight blocks	+	* Lightweight blocks.
−	* Thermal blocks	+	* Thermal blocks.
−	* Breeze blocks	+	* Breeze blocks.
−	* Insulation blocks	+	* Insulation blocks.
−	* Aircrete	+	* Aircrete.

	= Why trap air in concrete? =		= Why trap air in concrete? =

Editor at 07:19, 23 June 2023

2023-06-23T07:19:09Z

← Older revision		Revision as of 07:19, 23 June 2023
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	* Autoclaved aerated concrete (AAC)		* Autoclaved aerated concrete (AAC)
	* Reinforced autoclaved aerated concrete (RAAC)		* Reinforced autoclaved aerated concrete (RAAC)
−	* ~~cellular~~ concrete (CC)	+	* Cellular concrete (CC)
−	* ~~aerated~~ cellular concrete (ACC)	+	* Aerated cellular concrete (ACC)
−	* ~~aerated~~ lightweight concrete (ALC)	+	* Aerated lightweight concrete (ALC)
−	* ~~foamed~~ concrete	+	* Foamed concrete
−	* ~~lightweight~~ blocks	+	* Lightweight blocks
−	* ~~thermal~~ blocks	+	* Thermal blocks
−	* ~~breeze~~ blocks	+	* Breeze blocks
−	* ~~insulation~~ blocks	+	* Insulation blocks
−	* ~~aircrete~~	+	* Aircrete

	= Why trap air in concrete? =		= Why trap air in concrete? =

Editor at 07:17, 23 June 2023

2023-06-23T07:17:23Z

← Older revision		Revision as of 07:17, 23 June 2023
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	There are many different concrete products that contain air, these vary in the formulas used, how the products are processed, how much air and how it is arranged. There are many terms, sometimes describing the same or similar products as well as variations designed to achieve different performance criteria, and some are given below;		There are many different concrete products that contain air, these vary in the formulas used, how the products are processed, how much air and how it is arranged. There are many terms, sometimes describing the same or similar products as well as variations designed to achieve different performance criteria, and some are given below;

−	* ~~standard~~ concrete	+	* Standard concrete
−	* ~~aerated~~ concrete (AC) or non-autoclaved aerated concrete (NAAC)	+	* Aerated concrete (AC) or non-autoclaved aerated concrete (NAAC)
−	* ~~autoclaved~~ aerated concrete (AAC)	+	* Autoclaved aerated concrete (AAC)
−	* ~~reinforced~~ autoclaved aerated concrete (RAAC)	+	* Reinforced autoclaved aerated concrete (RAAC)
	* cellular concrete (CC)		* cellular concrete (CC)
	* aerated cellular concrete (ACC)		* aerated cellular concrete (ACC)

Designing Buildings at 06:30, 23 June 2023

2023-06-23T06:30:37Z

← Older revision		Revision as of 06:30, 23 June 2023
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	= What types of concrete products contain air? =		= What types of concrete products contain air? =

−	There are many different concrete products that contain air, these vary in the formulas used, how the products are processed, how much air and how it is arranged. There are many terms, sometimes describing the same or similar products as well as variations designed to achieve different performance criteria, some are given ~~here~~;	+	There are many different concrete products that contain air, these vary in the formulas used, how the products are processed, how much air and how it is arranged. There are many terms, sometimes describing the same or similar products as well as variations designed to achieve different performance criteria, and some are given below;

	* standard concrete		* standard concrete
Line 18:		Line 18:
	* insulation blocks		* insulation blocks
	* aircrete		* aircrete
−
−	~~to name a few.~~

	= Why trap air in concrete? =		= Why trap air in concrete? =
Line 25:		Line 23:
	== Standard concrete ==		== Standard concrete ==

−	Concrete compaction is an important part of pouring concrete, using tools such as a concrete vibrator helps agitate the mix in order to release excess trapped air. A general rule of thumb for a standard concrete mix is that strength ~~will for the material~~ will reduce by 6% for every 1% increase in trapped air. Despite agitation a standard concrete pour will normally contain around 1% ~~which is made up of~~ air.	+	Concrete compaction is an important part of pouring concrete, using tools such as a concrete vibrator helps agitate the mix in order to release excess trapped air. A general rule of thumb for a standard concrete mix is that strength will reduce by 6% for every 1% increase in trapped air. Despite agitation a standard concrete pour will normally contain around 1% air.

	== Entrapped air ==		== Entrapped air ==
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	== Entrained air ==		== Entrained air ==

−	Concrete that contains uniformly distributed microscopic bubbles of less than 1% throughout, can~~, on the other hand,~~ be beneficial to the final product. This type of trapped air is called air entrainment and usually makes up between 3%-8% by volume of a standard finished concrete product, that may also contain aggregates This entrained ~~air is~~ air can can help improve the performance of concrete in a number of ways.	+	Concrete that contains uniformly distributed microscopic bubbles of less than 1% throughout, can be beneficial to the final product. This type of trapped air is called air entrainment and usually makes up between 3%-8% by volume of a standard finished concrete product, that may also contain aggregates This entrained air can can help improve the performance of concrete in a number of ways.

	=== Even distribution ===		=== Even distribution ===

−	A certain amount of regular bubbles within a concrete mix increases the surface area of concrete (within the pour) which can help maintain a distribution moisture more evenly throughout the concrete, which reduces amount and the impacts of what is known as bleeding. Bleeding is where water within a concrete pour slowly rises to the surface, because it is the lightest of the materials (compared to sand, cement and aggregate)~~, this creates a pour that has a higher cement to water ratio at the surface~~. The higher the amount of bleeding the less evenly distributed the water is through out the pour and the less consistent the final product will be, increasing the surface area of concrete throughout the mix with entrained air reduces the bleed and keeps water evenly distributed throughout the mix so it dries more evenly and results in a more consistent final product.	+	A certain amount of regular bubbles within a concrete mix increases the surface area of concrete (within the pour) which can help maintain the distribution of moisture more evenly throughout the concrete, which reduces the amount and the impacts of what is known as bleeding. Bleeding is where water within a concrete pour slowly rises to the surface, because it is the lightest of the materials (compared to sand, cement and aggregate). The higher the amount of bleeding the less evenly distributed the water is through out the pour and the less consistent the final product will be, increasing the surface area of concrete throughout the mix with entrained air reduces the bleed and keeps water evenly distributed throughout the mix so it dries more evenly and results in a more consistent final product.

	=== Freeze thaw ===		=== Freeze thaw ===

−	Concrete installations in climates that at certain times of the year are prone to freeze may suffer from the freeze thaw effect as with other natural stones or rocks, which can over time lead to failure. Air entrainment can be beneficial in these climates because the tiny air bubbles distributed evenly throughout the concrete can act as expansion vessels during freezing temperatures when moisture ~~absorb~~ during wet periods expands ~~due to freezing conditions~~. Freeze thaw is a natural phenomenon that under normal conditions gradually ~~over time~~ creates cracks, splits and fault lines in natural rocks as water freezes, expands and then ~~defrosts~~, the same applies to concrete. The impacts of this can be significantly reduced through air entrainment thus improving the performance of concrete over time ~~through improved durability~~.	+	Concrete installations in climates that at certain times of the year are prone to freeze may suffer from the freeze thaw effect as with other natural stones or rocks, which can over time lead to failure. Air entrainment can be beneficial in these climates because the tiny air bubbles distributed evenly throughout the concrete can act as expansion vessels during freezing temperatures when moisture absorbed during wet periods expands. Freeze thaw is a natural phenomenon that under normal conditions gradually creates cracks, splits and fault lines in natural rocks as water freezes, expands and then thaws, the same applies to concrete. The impacts of this can be significantly reduced through air entrainment thus improving the performance of concrete over time.

	=== Workability ===		=== Workability ===

−	Finally because entrained air creates a more regular, even distribution of air throughout a mix the slurry is said to be more workable~~, especially is thicker and spread using hand trowels~~. It is also worth noting agitation is also required for entrained air concrete as it is poured as ready mixed products can contain higher percentages of air, particular in transportation. ~~Further more~~ changes in temperature can also impact the air content of a pre-prepared or ready mixed cement slurries with indications being that an increase of 30 degrees might decrease air content by up to 25%, whilst temperature drops of the same ~~acn~~ increase the air volume by up to 40%. These levels might then be reduced or balanced by agitation as the cement is poured in its final location.	+	Finally because entrained air creates a more regular, even distribution of air throughout a mix the slurry is said to be more workable. It is also worth noting agitation is also required for entrained air concrete as it is poured as ready mixed products can contain higher percentages of air, particular in transportation. Furthermore changes in temperature can also impact the air content of a pre-prepared or ready mixed cement slurries with indications being that an increase of 30 degrees might decrease air content by up to 25%, whilst temperature drops of the same can increase the air volume by up to 40%. These levels might then be reduced or balanced by agitation as the cement is poured in its final location.

	== Cellular air ==		== Cellular air ==

−	When the air trapped within cement increases significantly, with mixes containing anything above 25% and up to around 85% air by volume, the strength of concrete is reduced but other characteristics develop, which can be advantageous. This type of concrete is usually referred to as cellular or aerated concrete, and can be formed ~~in to~~ lightweight, insulative, thermal or fire blocking products such as blocks or panels, but also used on bespoke ~~form work~~. Importantly the ingredients of this type of concrete differ from standard concrete, and it does not contain aggregate or only fine aggregates such as fine sand. The main advantages of higher levels of trapped air in concrete mixes ~~might be~~ described ~~asc being;~~	+	When the air trapped within cement increases significantly, with mixes containing anything above 25% and up to around 85% air by volume, the strength of concrete is reduced but other characteristics develop, which can be advantageous. This type of concrete is usually referred to as cellular or aerated concrete, and can be formed into lightweight, insulative, thermal or fire blocking products such as blocks or panels, but also used on bespoke formwork. Importantly the ingredients of this type of concrete differ from standard concrete, and it does not contain aggregate or only fine aggregates such as fine sand. The main advantages of higher levels of trapped air in concrete mixes are described below.

	=== Material efficiency ===		=== Material efficiency ===
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	=== Thermal performance ===		=== Thermal performance ===

−	The air cells within the concrete improve the thermal resistance of concrete, so much so that they have some insulative properties. The thermal performance increases as the air percentage increases, which will also impact the strength of the block which will decrease. One other advantage is that such concrete products can retain certain levels of thermal mass as well as insulative qualities which can help regulate the temperature of internal environments.	+	The air cells within the concrete improve the thermal resistance of concrete, so much that they have some insulative properties. The thermal performance increases as the air percentage increases, which will also impact the strength of the block which will decrease. One other advantage is that such concrete products can retain certain levels of thermal mass as well as having insulative qualities which can help regulate the temperature of internal environments.

	=== Weight and use ===		=== Weight and use ===

−	As cellular concrete is lighter it can reduce transport costs as well as having site safety benefits in being easier to work with. There is also some evidence to show that because of the lighter weight, buildings constructed in seismic areas will perform better under earthquake conditions as seismic transmission is reduce because of the weight difference. Because of the weight larger ~~block~~ or panels can be used, which speeds the building process up.	+	As cellular concrete is lighter it can reduce transport costs as well as having site safety benefits in being easier to work with. There is also some evidence to show that because of the lighter weight, buildings constructed in seismic areas will perform better under earthquake conditions as seismic transmission is reduce because of the weight difference. Because of the weight, larger blocks or panels can be used, which speeds the building process up.

	=== Acoustic performance ===		=== Acoustic performance ===
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	=== Permeability ===		=== Permeability ===

−	Because of the many independent small bubbles or pores, are closed, water absorption and moisture conduction are generally slow, whilst the finish faces can easily be plastered, ~~pained~~ or tiled to act as a further seal.	+	Because the many independent small bubbles or pores, are closed, water absorption and moisture conduction are generally slow, whilst the finish faces can easily be plastered, painted or tiled to act as a further seal.

	= How is the air trapped into the concrete ? =		= How is the air trapped into the concrete ? =

−	Admixtures are ingredients that are are added to a concrete mixture whilst it is being prepared and before pouring, as opposed to additives which are added to the cement when it is being manufactured. There are many different admixtures used in the concrete industry to perform different tasks for example	+	Admixtures are ingredients that are are added to a concrete mixture whilst it is being prepared and before pouring, as opposed to additives which are added to the cement when it is being manufactured. There are many different admixtures used in the concrete industry to perform different tasks, for example:

	* Water reducing admixtures come as standard, mid-range plasticisers (Calcium, sodium and ammonium lignosulphonates) and super plasticisers (poly carboxylate, multicarbovylatethers), reduce the water demand by 10% to 30%.		* Water reducing admixtures come as standard, mid-range plasticisers (Calcium, sodium and ammonium lignosulphonates) and super plasticisers (poly carboxylate, multicarbovylatethers), reduce the water demand by 10% to 30%.
	* Retarding admixtures (or retarding plasticicers) slow down the rate of hydration such as calcium sulphate, gypsum, starch, cellulose, common sugars, and salts of acids.		* Retarding admixtures (or retarding plasticicers) slow down the rate of hydration such as calcium sulphate, gypsum, starch, cellulose, common sugars, and salts of acids.
−	* Accelerating ~~Admixtures~~ speed up the setting time of concrete, calcium chloride ~~bis~~ one of the most common but they also include triethenolamine, calcium formate, silica fume, fine silica gels.	+	* Accelerating admixtures speed up the setting time of concrete, calcium chloride is one of the most common but they also include triethenolamine, calcium formate, silica fume, fine silica gels.
−	* Pozzolanic admixtures are sometimes used to reduce cementitious material in concrete and can help reduce risks associated with certain unwanted chemical reactions such as sulfate attack, leaching and alkali aggregate reactions. Such admixtures can be ~~man-made~~ (fly ash, blast furnace slag, silica fume and rice husk ashes) or naturally occurring (clays, shale, volcanic tuffs, pumicite).	+	* Pozzolanic admixtures are sometimes used to reduce cementitious material in concrete and can help reduce risks associated with certain unwanted chemical reactions such as sulfate attack, leaching and alkali aggregate reactions. Such admixtures can be artificial (fly ash, blast furnace slag, silica fume and rice husk ashes) or naturally occurring (clays, shale, volcanic tuffs, pumicite).

−	The admixtures above also tend to increase the air content within concrete as a by effect, except for accelerators and pozzolans. There is a long list of other admixtures used for damp proofing, colour adjustment and to combat specific durability issues and attacks including fungal growth, pests and corrosion, as well as to improve bonding. Air detraining additives are designed to help remove excess air from concrete, such as water insoluble alcohols, phosphate and silicones.	+	The admixtures above also tend to increase the air content within concrete as a side effect, except for accelerators and pozzolans. There is a long list of other admixtures used for damp proofing, colour adjustment and to combat specific durability issues and attacks including fungal growth, pests and corrosion, as well as to improve bonding. Air detraining additives are designed to help remove excess air from concrete, such as water insoluble alcohols, phosphate and silicones.

	== Air entraining agents ==		== Air entraining agents ==

−	~~Finally air~~ entraining admixtures help to increase air content, many of which are referred to as surfactants, which stands for surface active agents, and have a water repelling or hydrophobic chain (non-polar hydrocarbon) and water attractive or hydrophilic chain (anionic polar). Formally there are two main classifications of air-entraining admixtures which are wood-derived acid salts (vinsol resins and wood rosins) and synthetic resins (such as foam). Essentially these are either added to the initial mix and create gas pockets through the chemical reactions that occur as water is added and the concrete hardens, known as air entraining agents or the prepared slurry is mixed with them to introduce air pockets which might be called foaming agents (although some air entraining agents are also referred to as foaming agents!).	+	Air entraining admixtures help to increase air content, many of which are referred to as surfactants, which stands for surface active agents, and have a water repelling or hydrophobic chain (non-polar hydrocarbon) and water attractive or hydrophilic chain (anionic polar). Formally there are two main classifications of air-entraining admixtures which are wood-derived acid salts (vinsol resins and wood rosins) and synthetic resins (such as foam). Essentially these are either added to the initial mix and create gas pockets through the chemical reactions that occur as water is added and the concrete hardens, known as air entraining agents or the prepared slurry is mixed with them to introduce air pockets which might be called foaming agents (although some air entraining agents are also referred to as foaming agents).

	One example of a foaming agent added to the initial mix is aluminium powder, it reacts with the calcium hydroxide formed on the hydration of cement to produce hydrogen gas bubbles. The agent is mixed with a fine aggregate (usually sand or fly ash), cement, lime, gypsum, and water and reacts on hydration creating air pockets. These types of air entrained concretes are normally referred to as cellular concrete or aerated concrete (AC). Variation on these types of products include autoclaved aerated concrete (AAC) which is essentially the same but once poured and setting, it is placed in an autoclave which applies steam and pressure, this speeds up the curing process and creates a stronger product. Another variation is reinforced autoclaved aerated concrete (AAC) which includes some form of reinforcement to improve the tensile strength of the product and always larger unit sizes to be formed.		One example of a foaming agent added to the initial mix is aluminium powder, it reacts with the calcium hydroxide formed on the hydration of cement to produce hydrogen gas bubbles. The agent is mixed with a fine aggregate (usually sand or fly ash), cement, lime, gypsum, and water and reacts on hydration creating air pockets. These types of air entrained concretes are normally referred to as cellular concrete or aerated concrete (AC). Variation on these types of products include autoclaved aerated concrete (AAC) which is essentially the same but once poured and setting, it is placed in an autoclave which applies steam and pressure, this speeds up the curing process and creates a stronger product. Another variation is reinforced autoclaved aerated concrete (AAC) which includes some form of reinforcement to improve the tensile strength of the product and always larger unit sizes to be formed.

Editor at 04:33, 23 June 2023

2023-06-23T04:33:16Z

← Older revision		Revision as of 04:33, 23 June 2023
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	[[File:Concrete_round_bubbles_1000.jpg\|link=File:Concrete_round_bubbles_1000.jpg]]		[[File:Concrete_round_bubbles_1000.jpg\|link=File:Concrete_round_bubbles_1000.jpg]]

−	= What types of concrete products contain air ? =	+	= What types of concrete products contain air? =

	There are many different concrete products that contain air, these vary in the formulas used, how the products are processed, how much air and how it is arranged. There are many terms, sometimes describing the same or similar products as well as variations designed to achieve different performance criteria, some are given here;		There are many different concrete products that contain air, these vary in the formulas used, how the products are processed, how much air and how it is arranged. There are many terms, sometimes describing the same or similar products as well as variations designed to achieve different performance criteria, some are given here;
Line 25:		Line 25:
	== Standard concrete ==		== Standard concrete ==

−	Concrete compaction is an important part of pouring concrete, using tools such as a concrete vibrator helps ~~agitates~~ the mix in order to release excess trapped air. A general rule of thumb for a standard concrete mix is that strength will for the material will reduce by 6% for every 1% increase in trapped air. Despite agitation a standard concrete pour will normally contain around 1% which is made up of air.	+	Concrete compaction is an important part of pouring concrete, using tools such as a concrete vibrator helps agitate the mix in order to release excess trapped air. A general rule of thumb for a standard concrete mix is that strength will for the material will reduce by 6% for every 1% increase in trapped air. Despite agitation a standard concrete pour will normally contain around 1% which is made up of air.

	== Entrapped air ==		== Entrapped air ==

−	When the air content within concrete is about 1.5% - 3% bubbles are relatively large in size, over around 1mm and randomly located throughout the mix. This is referred to as entrapped air, in most cases an unintended consequence of mixing concrete, with higher percentages resulting from insufficient agitation when the mix is poured. So if the strength of concrete decreases with air, why would a contractor or manufacturers want to trap air ?	+	When the air content within concrete is about 1% - 3% bubbles are relatively large in size, over around 1mm and randomly located throughout the mix. This is referred to as entrapped air, in most cases an unintended consequence of mixing concrete, with higher percentages resulting from insufficient agitation when the mix is poured. So if the strength of concrete decreases with air, why would a contractor or manufacturers want to trap air?

	== Entrained air ==		== Entrained air ==

−	Concrete that contains uniformly distributed microscopic bubbles of less than 1% throughout can, on the other hand, be beneficial to the final product. This type of trapped air is called air entrainment and usually makes up between 3%-8% by volume of ~~the~~ finished product. This entrained air can can help improve the performance of concrete in a number of ways.	+	Concrete that contains uniformly distributed microscopic bubbles of less than 1% throughout, can, on the other hand, be beneficial to the final product. This type of trapped air is called air entrainment and usually makes up between 3%-8% by volume of a standard finished concrete product, that may also contain aggregates This entrained air is air can can help improve the performance of concrete in a number of ways.

	=== Even distribution ===		=== Even distribution ===
Line 49:		Line 49:
	== Cellular air ==		== Cellular air ==

−	When the air trapped within cement increases significantly as with mixes containing anything above 25% and up to around 85% air by volume the strength of concrete is reduced but other characteristics develop, which can be advantageous. This type of concrete is usually referred to as cellular or aerated concrete, and can be formed in to lightweight, insulative, thermal or fire blocking products such as blocks or panels, but also used on bespoke form work. The main advantages of higher levels of trapped air in concrete mixes might be described as;	+	When the air trapped within cement increases significantly, with mixes containing anything above 25% and up to around 85% air by volume, the strength of concrete is reduced but other characteristics develop, which can be advantageous. This type of concrete is usually referred to as cellular or aerated concrete, and can be formed in to lightweight, insulative, thermal or fire blocking products such as blocks or panels, but also used on bespoke form work. Importantly the ingredients of this type of concrete differ from standard concrete, and it does not contain aggregate or only fine aggregates such as fine sand. The main advantages of higher levels of trapped air in concrete mixes might be described asc being;

	=== Material efficiency ===		=== Material efficiency ===
Line 90:		Line 90:
	Finally air entraining admixtures help to increase air content, many of which are referred to as surfactants, which stands for surface active agents, and have a water repelling or hydrophobic chain (non-polar hydrocarbon) and water attractive or hydrophilic chain (anionic polar). Formally there are two main classifications of air-entraining admixtures which are wood-derived acid salts (vinsol resins and wood rosins) and synthetic resins (such as foam). Essentially these are either added to the initial mix and create gas pockets through the chemical reactions that occur as water is added and the concrete hardens, known as air entraining agents or the prepared slurry is mixed with them to introduce air pockets which might be called foaming agents (although some air entraining agents are also referred to as foaming agents!).		Finally air entraining admixtures help to increase air content, many of which are referred to as surfactants, which stands for surface active agents, and have a water repelling or hydrophobic chain (non-polar hydrocarbon) and water attractive or hydrophilic chain (anionic polar). Formally there are two main classifications of air-entraining admixtures which are wood-derived acid salts (vinsol resins and wood rosins) and synthetic resins (such as foam). Essentially these are either added to the initial mix and create gas pockets through the chemical reactions that occur as water is added and the concrete hardens, known as air entraining agents or the prepared slurry is mixed with them to introduce air pockets which might be called foaming agents (although some air entraining agents are also referred to as foaming agents!).

−	One example of a foaming agent added to the initial mix is aluminium powder, it reacts with the calcium hydroxide formed on hydration of cement to produce hydrogen gas bubbles. The agent is mixed with ~~the~~ a fine aggregate (usually sand or fly ash), cement, lime, gypsum, and water and reacts on hydration creating pockets. These types of air entrained concretes are normally referred to as cellular concrete or aerated concrete (AC). Variation on these types of products include autoclaved aerated concrete (AAC) which is essentially the same but once poured and setting is placed in an autoclave which applies steam and pressure, this speeds up the curing process and creates a stronger product. Another variation is reinforced autoclaved aerated concrete (AAC) which includes some form of reinforcement to improve the tensile strength of the product.	+	One example of a foaming agent added to the initial mix is aluminium powder, it reacts with the calcium hydroxide formed on the hydration of cement to produce hydrogen gas bubbles. The agent is mixed with a fine aggregate (usually sand or fly ash), cement, lime, gypsum, and water and reacts on hydration creating air pockets. These types of air entrained concretes are normally referred to as cellular concrete or aerated concrete (AC). Variation on these types of products include autoclaved aerated concrete (AAC) which is essentially the same but once poured and setting, it is placed in an autoclave which applies steam and pressure, this speeds up the curing process and creates a stronger product. Another variation is reinforced autoclaved aerated concrete (AAC) which includes some form of reinforcement to improve the tensile strength of the product and always larger unit sizes to be formed.

	== Foaming agents ==		== Foaming agents ==

Editor at 22:13, 22 June 2023

2023-06-22T22:13:34Z

← Older revision		Revision as of 22:13, 22 June 2023
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	* autoclaved aerated concrete (AAC)		* autoclaved aerated concrete (AAC)
	* reinforced autoclaved aerated concrete (RAAC)		* reinforced autoclaved aerated concrete (RAAC)
		+	* cellular concrete (CC)
	* aerated cellular concrete (ACC)		* aerated cellular concrete (ACC)
	* aerated lightweight concrete (ALC)		* aerated lightweight concrete (ALC)

Editor at 21:43, 22 June 2023

2023-06-22T21:43:31Z

← Older revision		Revision as of 21:43, 22 June 2023
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	= What types of concrete products contain air ? =		= What types of concrete products contain air ? =

−	There are many different concrete products that contain air, these vary in the formulas used, how the products are processed, how much air and how it is arranged. There are many terms, sometimes describing the same or similar products as well as variations designed to achieve different performance criteria ~~such as~~;	+	There are many different concrete products that contain air, these vary in the formulas used, how the products are processed, how much air and how it is arranged. There are many terms, sometimes describing the same or similar products as well as variations designed to achieve different performance criteria, some are given here;

	* standard concrete		* standard concrete
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	== Cellular air ==		== Cellular air ==

−	When the air trapped within cement increases significantly as with mixes containing anything above 25% air by volume the strength of concrete is reduced but other characteristics develop, which can be advantageous. This type of concrete is usually referred to as cellular or aerated concrete, ~~which~~ can be formed in to lightweight, insulative, thermal or fire blocking products such as blocks or panels. The main advantages of higher levels of trapped air in concrete mixes ~~are~~;	+	When the air trapped within cement increases significantly as with mixes containing anything above 25% and up to around 85% air by volume the strength of concrete is reduced but other characteristics develop, which can be advantageous. This type of concrete is usually referred to as cellular or aerated concrete, and can be formed in to lightweight, insulative, thermal or fire blocking products such as blocks or panels, but also used on bespoke form work. The main advantages of higher levels of trapped air in concrete mixes might be described as;

	=== Material efficiency ===		=== Material efficiency ===
Line 78:		Line 78:
	Admixtures are ingredients that are are added to a concrete mixture whilst it is being prepared and before pouring, as opposed to additives which are added to the cement when it is being manufactured. There are many different admixtures used in the concrete industry to perform different tasks for example		Admixtures are ingredients that are are added to a concrete mixture whilst it is being prepared and before pouring, as opposed to additives which are added to the cement when it is being manufactured. There are many different admixtures used in the concrete industry to perform different tasks for example

−	* Water reducing ~~ddmixtures~~ come as standard, mid-range plasticisers (Calcium, sodium and ammonium lignosulphonates) and super ~~plasticicers~~ (poly carboxylate, multicarbovylatethers), reduce the water demand by 10% to 30%.	+	* Water reducing admixtures come as standard, mid-range plasticisers (Calcium, sodium and ammonium lignosulphonates) and super plasticisers (poly carboxylate, multicarbovylatethers), reduce the water demand by 10% to 30%.
	* Retarding admixtures (or retarding plasticicers) slow down the rate of hydration such as calcium sulphate, gypsum, starch, cellulose, common sugars, and salts of acids.		* Retarding admixtures (or retarding plasticicers) slow down the rate of hydration such as calcium sulphate, gypsum, starch, cellulose, common sugars, and salts of acids.
	* Accelerating Admixtures speed up the setting time of concrete, calcium chloride bis one of the most common but they also include triethenolamine, calcium formate, silica fume, fine silica gels.		* Accelerating Admixtures speed up the setting time of concrete, calcium chloride bis one of the most common but they also include triethenolamine, calcium formate, silica fume, fine silica gels.
−	* Pozzolanic admixtures are sometimes used to reduce cementitious material in concrete and can help reduce risks associated with certain unwanted chemical ~~reations~~ such as sulfate attack, leaching and alkali aggregate reactions. Such admixtures can be man-made (fly ash, blast furnace slag, silica fume and rice husk ashes) or naturally occurring (clays, shale, volcanic tuffs, pumicite).	+	* Pozzolanic admixtures are sometimes used to reduce cementitious material in concrete and can help reduce risks associated with certain unwanted chemical reactions such as sulfate attack, leaching and alkali aggregate reactions. Such admixtures can be man-made (fly ash, blast furnace slag, silica fume and rice husk ashes) or naturally occurring (clays, shale, volcanic tuffs, pumicite).

	The admixtures above also tend to increase the air content within concrete as a by effect, except for accelerators and pozzolans. There is a long list of other admixtures used for damp proofing, colour adjustment and to combat specific durability issues and attacks including fungal growth, pests and corrosion, as well as to improve bonding. Air detraining additives are designed to help remove excess air from concrete, such as water insoluble alcohols, phosphate and silicones.		The admixtures above also tend to increase the air content within concrete as a by effect, except for accelerators and pozzolans. There is a long list of other admixtures used for damp proofing, colour adjustment and to combat specific durability issues and attacks including fungal growth, pests and corrosion, as well as to improve bonding. Air detraining additives are designed to help remove excess air from concrete, such as water insoluble alcohols, phosphate and silicones.
−
−	~~= Air entraining agents =~~
−
−	Finally air entraining admixtures help to increase air content, many of which are referred to as surfactants, which stands for surface active agents, and have a water repelling or hydrophobic chain (non-polar hydrocarbon) and water attractive or hydrophilic chain (anionic polar). Formally there are two main classifications of air-entraining admixtures which are wood-derived acid salts (vinsol resins and wood rosins) and synthetic resins (such as foam). Essentially these are either added to the initial mix and create gas pockets through the chemical reactions occurring as water is added and the concrete hardens, known as air entraining agents or the prepared slurry is mixed with them to introduce air pockets which might be called foaming agents (although some air entraining agents are referred to as foaming agents!). In many way it relates to how and at what stage the pockets of air are introduced.

	== Air entraining agents ==		== Air entraining agents ==

−	~~One example~~ of ~~a foaming agent~~ which ~~is is aluminium powder~~, which is a ~~foaming agent that reacts with the calcium hydroxide formed on hydration of cement to produce hydrogen gas bubbles. The agent is mixed with the a fine aggregate~~ (~~usually sand or fly ash~~)~~, cement, lime, gypsum,~~ and water ~~and reacts on hydration creating air~~. ~~There~~ are two main classifications of air-entraining admixtures which ~~used to trap air in concrete these~~ are wood-derived acid salts (vinsol resins and wood rosins) and synthetic resins (such as foam).	+	Finally air entraining admixtures help to increase air content, many of which are referred to as surfactants, which stands for surface active agents, and have a water repelling or hydrophobic chain (non-polar hydrocarbon) and water attractive or hydrophilic chain (anionic polar). Formally there are two main classifications of air-entraining admixtures which are wood-derived acid salts (vinsol resins and wood rosins) and synthetic resins (such as foam). Essentially these are either added to the initial mix and create gas pockets through the chemical reactions that occur as water is added and the concrete hardens, known as air entraining agents or the prepared slurry is mixed with them to introduce air pockets which might be called foaming agents (although some air entraining agents are also referred to as foaming agents!).

−	~~tall oil fatty acids~~, ~~gum~~ and ~~wood rosins~~, and ~~sulfonated hydrocarbons~~	+	One example of a foaming agent added to the initial mix is aluminium powder, it reacts with the calcium hydroxide formed on hydration of cement to produce hydrogen gas bubbles. The agent is mixed with the a fine aggregate (usually sand or fly ash), cement, lime, gypsum, and water and reacts on hydration creating pockets. These types of air entrained concretes are normally referred to as cellular concrete or aerated concrete (AC). Variation on these types of products include autoclaved aerated concrete (AAC) which is essentially the same but once poured and setting is placed in an autoclave which applies steam and pressure, this speeds up the curing process and creates a stronger product. Another variation is reinforced autoclaved aerated concrete (AAC) which includes some form of reinforcement to improve the tensile strength of the product.

−	Foaming agents	+	== Foaming agents ==
		+
		+	Whilst some foaming agents are used at the initial stages of the mix and create air pockets through chemical reactions during curing, foaming agents that produce foamed concrete (also called aircrete) tend to refer to a slightly different process. In many ways simpler but perhaps less controlled this process involves making a slurry with all the normal ingredients (minus larger aggregates) and then creating a stable foam separately containing air pockets, these two elements ae then mixed to create a foamed slurry mix. when this mix sets evenly the pockets of air incorporated into the foam become part of the concrete. Such products can be made with industrial foaming agents and foam tools but they can also be made with standard household foam liquids such as detergents and washing up liquid.

	= Related articles on Designing Buildings =		= Related articles on Designing Buildings =

−	[[Category:~~Articles_needing_more_work~~]]	+	* Aircrete.
		+	* Aircrete blocks.
		+	* Alkali-activated binder.
		+	* Alkali-aggregate reaction (AAR).
		+	* Applications, performance characteristics and environmental benefits of alkali-activated binder concretes.
		+	* Blockwork.
		+	* Cellular concrete.
		+	* Fly ash.
		+	* Formwork.
		+	* Precast concrete.
		+	* Self-compacting concrete.
		+	* Smart concrete.
		+	* Types of concrete.
		+	* Types of concrete specification.
		+
		+	[[Category:DCN_Commentary]] [[Category:DCN_Definition]] [[Category:DCN_Product_Knowledge]] [[Category:DCN_Specification]] [[Category:Definitions]] [[Category:Standards_/_measurements]] [[Category:Sustainability]] [[Category:Products_/_components]]

Editor at 20:57, 22 June 2023

2023-06-22T20:57:39Z

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	The admixtures above also tend to increase the air content within concrete as a by effect, except for accelerators and pozzolans. There is a long list of other admixtures used for damp proofing, colour adjustment and to combat specific durability issues and attacks including fungal growth, pests and corrosion, as well as to improve bonding. Air detraining additives are designed to help remove excess air from concrete, such as water insoluble alcohols, phosphate and silicones.		The admixtures above also tend to increase the air content within concrete as a by effect, except for accelerators and pozzolans. There is a long list of other admixtures used for damp proofing, colour adjustment and to combat specific durability issues and attacks including fungal growth, pests and corrosion, as well as to improve bonding. Air detraining additives are designed to help remove excess air from concrete, such as water insoluble alcohols, phosphate and silicones.

−	~~Finally air~~ entraining ~~admixtures help to increase air content, many of which are refered to as surfactants, which stands for surface active~~ agents, and have a water repelling or hydrophobic chain (non-polar hydrocarbon) and water attractive or hydrophilic chain (anionic polar). Formally there are two main classifications of air-entraining admixtures which are wood-derived acid salts (vinsol resins and wood rosins) and synthetic resins (such as foam).	+	= Air entraining agents =

−	~~== Air~~ entraining agents ==	+	Finally air entraining admixtures help to increase air content, many of which are referred to as surfactants, which stands for surface active agents, and have a water repelling or hydrophobic chain (non-polar hydrocarbon) and water attractive or hydrophilic chain (anionic polar). Formally there are two main classifications of air-entraining admixtures which are wood-derived acid salts (vinsol resins and wood rosins) and synthetic resins (such as foam). Essentially these are either added to the initial mix and create gas pockets through the chemical reactions occurring as water is added and the concrete hardens, known as air entraining agents or the prepared slurry is mixed with them to introduce air pockets which might be called foaming agents (although some air entraining agents are referred to as foaming agents!). In many way it relates to how and at what stage the pockets of air are introduced.

−	~~Differing products contain different ingredients and vary the processes, however in general the two main basic approaches that are used. The first approach makes use of an air-~~entraining agents (AEA) are ingredients that are added to a dry mix and via a chemical reaction with the concrete process create tiny pockets of gas throughout the finished product. Th The second might be referred to as foaming agents which	+	== Air entraining agents ==

−	One ~~such~~ example is aluminium powder, which is a foaming agent that reacts with the calcium hydroxide formed on hydration of cement to produce hydrogen gas bubbles. The agent is mixed with the a fine aggregate (usually sand or fly ash), cement, lime, gypsum, and water and reacts on hydration creating air. There are two main classifications of air-entraining admixtures which used to trap air in concrete these are wood-derived acid salts (vinsol resins and wood rosins) and synthetic resins (such as foam).	+	One example of a foaming agent which is is aluminium powder, which is a foaming agent that reacts with the calcium hydroxide formed on hydration of cement to produce hydrogen gas bubbles. The agent is mixed with the a fine aggregate (usually sand or fly ash), cement, lime, gypsum, and water and reacts on hydration creating air. There are two main classifications of air-entraining admixtures which used to trap air in concrete these are wood-derived acid salts (vinsol resins and wood rosins) and synthetic resins (such as foam).

	tall oil fatty acids, gum and wood rosins, and sulfonated hydrocarbons		tall oil fatty acids, gum and wood rosins, and sulfonated hydrocarbons

Editor at 20:48, 22 June 2023

2023-06-22T20:48:05Z

← Older revision		Revision as of 20:48, 22 June 2023
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	Admixtures are ingredients that are are added to a concrete mixture whilst it is being prepared and before pouring, as opposed to additives which are added to the cement when it is being manufactured. There are many different admixtures used in the concrete industry to perform different tasks for example		Admixtures are ingredients that are are added to a concrete mixture whilst it is being prepared and before pouring, as opposed to additives which are added to the cement when it is being manufactured. There are many different admixtures used in the concrete industry to perform different tasks for example

−	Water ~~Reducing Admixtures -~~ standard, mid-range ~~plasticizers~~ (Calcium, sodium and ammonium lignosulphonates) and super ~~plasticizers~~ (poly carboxylate, multicarbovylatethers), reduce the water demand by 10% to 30%.	+	* Water reducing ddmixtures come as standard, mid-range plasticisers (Calcium, sodium and ammonium lignosulphonates) and super plasticicers (poly carboxylate, multicarbovylatethers), reduce the water demand by 10% to 30%.
		+	* Retarding admixtures (or retarding plasticicers) slow down the rate of hydration such as calcium sulphate, gypsum, starch, cellulose, common sugars, and salts of acids.
		+	* Accelerating Admixtures speed up the setting time of concrete, calcium chloride bis one of the most common but they also include triethenolamine, calcium formate, silica fume, fine silica gels.
		+	* Pozzolanic admixtures are sometimes used to reduce cementitious material in concrete and can help reduce risks associated with certain unwanted chemical reations such as sulfate attack, leaching and alkali aggregate reactions. Such admixtures can be man-made (fly ash, blast furnace slag, silica fume and rice husk ashes) or naturally occurring (clays, shale, volcanic tuffs, pumicite).

−	~~Retarding~~ admixtures ~~(or retarding plasticizers) slow down~~ the ~~rate of hydration such~~ as ~~calcium sulphate~~, ~~gypsum~~, ~~starch~~, ~~cellulose~~, ~~common sugars~~, and ~~salts of acids~~.	+	The admixtures above also tend to increase the air content within concrete as a by effect, except for accelerators and pozzolans. There is a long list of other admixtures used for damp proofing, colour adjustment and to combat specific durability issues and attacks including fungal growth, pests and corrosion, as well as to improve bonding. Air detraining additives are designed to help remove excess air from concrete, such as water insoluble alcohols, phosphate and silicones.

−	~~Accelerating Admixtures~~	+	Finally air entraining admixtures help to increase air content, many of which are refered to as surfactants, which stands for surface active agents, and have a water repelling or hydrophobic chain (non-polar hydrocarbon) and water attractive or hydrophilic chain (anionic polar). Formally there are two main classifications of air-entraining admixtures which are wood-derived acid salts (vinsol resins and wood rosins) and synthetic resins (such as foam).
−		+
−	~~Most products use~~ admixtures to ~~trap~~ air ~~into the products~~, ~~the admixtures used~~ are ~~called~~ surfactants which stands for surface active agents, ~~these~~ have water repelling or a hydrophobic chain (non-polar hydrocarbon) and water attractive or hydrophilic chain (anionic polar). Formally there are two main classifications of air-entraining admixtures which are wood-derived acid salts (vinsol resins and wood rosins) and synthetic resins (such as foam).	+

	== Air entraining agents ==		== Air entraining agents ==

−	Differing products contain different ingredients and vary the processes, however in general the two main basic approaches used~~, which are often named differently~~. The first approach makes use of an air-entraining agents (AEA) ~~which is spread evenly throughout the~~ mix and ~~through~~ a chemical reaction ~~creates~~ tiny pockets of ~~air spread~~ throughout the ~~mixture~~. One such example is aluminium powder, which is a foaming agent that reacts with the calcium hydroxide formed on hydration of cement to produce hydrogen gas bubbles. The agent is mixed with the a fine aggregate (usually sand or fly ash), cement, lime, gypsum, and water and reacts on hydration creating air. There are two main classifications of air-entraining admixtures which used to trap air in concrete these are wood-derived acid salts (vinsol resins and wood rosins) and synthetic resins (such as foam).	+	Differing products contain different ingredients and vary the processes, however in general the two main basic approaches that are used. The first approach makes use of an air-entraining agents (AEA) are ingredients that are added to a dry mix and via a chemical reaction with the concrete process create tiny pockets of gas throughout the finished product. Th The second might be referred to as foaming agents which
		+
		+	One such example is aluminium powder, which is a foaming agent that reacts with the calcium hydroxide formed on hydration of cement to produce hydrogen gas bubbles. The agent is mixed with the a fine aggregate (usually sand or fly ash), cement, lime, gypsum, and water and reacts on hydration creating air. There are two main classifications of air-entraining admixtures which used to trap air in concrete these are wood-derived acid salts (vinsol resins and wood rosins) and synthetic resins (such as foam).

	tall oil fatty acids, gum and wood rosins, and sulfonated hydrocarbons		tall oil fatty acids, gum and wood rosins, and sulfonated hydrocarbons

Editor at 18:29, 22 June 2023

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← Older revision		Revision as of 18:29, 22 June 2023
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	* standard concrete		* standard concrete
−	* aerated concrete (AC)	+	* aerated concrete (AC) or non-autoclaved aerated concrete (NAAC)
	* autoclaved aerated concrete (AAC)		* autoclaved aerated concrete (AAC)
−	* non-autoclaved aerated concrete (NAAC)
	* reinforced autoclaved aerated concrete (RAAC)		* reinforced autoclaved aerated concrete (RAAC)
	* aerated cellular concrete (ACC)		* aerated cellular concrete (ACC)