Curing - Revision history

Designing Buildings at 08:03, 27 December 2021

2021-12-27T08:03:52Z

← Older revision		Revision as of 08:03, 27 December 2021
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	* Size and shape of concrete being cast.		* Size and shape of concrete being cast.

−	= Related articles on Designing Buildings ~~Wiki~~ =	+	See also: Carbon dioxide curing.
		+
		+	= Related articles on Designing Buildings =

	* Admixture, additive or agent.		* Admixture, additive or agent.
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	* Alkali-aggregate reaction (AAR).		* Alkali-aggregate reaction (AAR).
	* Alkali-silica reaction (ASR).		* Alkali-silica reaction (ASR).
−	* ~~Cast-in-place concrete~~.	+	* Carbon dioxide curing.
	* Compressive strength.		* Compressive strength.
−	* Floor slab.
	* Laitance.		* Laitance.
	* Portland cement.		* Portland cement.

Editor: Reverted edits by 103.251.19.201 (talk) to last revision by Designing Buildings

2021-07-08T09:28:11Z

Reverted edits by 103.251.19.201 (talk) to last revision by Designing Buildings

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Designing Buildings at 07:04, 4 February 2021

2021-02-04T07:04:22Z

← Older revision		Revision as of 07:04, 4 February 2021
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−	[[File:Reinforcedconcrete.jpg]]	+	[[File:Reinforcedconcrete.jpg\|link=File:Reinforcedconcrete.jpg]]

	= Introduction =		= Introduction =
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	* The properties of concrete.		* The properties of concrete.

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

Designing Buildings at 12:08, 14 January 2020

2020-01-14T12:08:34Z

← Older revision		Revision as of 12:08, 14 January 2020
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		+	[[File:Reinforcedconcrete.jpg]]
		+
	= Introduction =		= Introduction =

−	Curing is a term applied to the chemical process that describes a change in the state of ~~various~~ materials, usually as they turn from liquid (or semi-liquid) to solid. It can apply to cement, concrete, adhesives, plasters, thermosetting plastics and other materials. It usually has important implications for strength development ~~and therefore the construction process~~ and so its effects ~~should~~ be considered carefully~~. One of~~ the ~~materials for which curing is critical is concrete~~.	+	Curing is a term applied to the chemical process that describes a change in the state of materials, usually as they turn from liquid (or semi-liquid) to solid. It can apply to cement, concrete, adhesives, plasters, thermosetting plastics and other materials. It usually has important implications for strength development and so its effects must be considered carefully in the construction industry.

	= Concrete =		= Concrete =

−	The curing time for cast-in-place concrete can be anything from three days to two weeks. The process ~~of concrete setting~~ involves an exothermic reaction, i.e heat is given off ~~which requires proper curing~~. Ensuring the correct conditions for curing requires protecting the concrete from both high and low temperatures.	+	The curing time for cast-in-place concrete can be anything from three days to two weeks. The process involves an exothermic reaction, i.e heat is given off. Ensuring the correct conditions for curing requires protecting the concrete from both high and low temperatures.

	If freshly-poured concrete is not cured properly, it may:		If freshly-poured concrete is not cured properly, it may:
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	* Have an ultimate strength lower than the required design strength.		* Have an ultimate strength lower than the required design strength.

−	Both consequences could be catastrophic as cracks can allow the ingress of humidity and water which can cause corrosion of steel reinforcement; while failing to reach its design strength will mean a weaker concrete than designed with ~~potential catastrophic~~ consequences.	+	Both consequences could be catastrophic as cracks can allow the ingress of humidity and water which can cause corrosion of steel reinforcement or frost damage; while failing to reach its design strength will mean a weaker concrete than designed with potentially serious consequences.

−	= Hydration =	+	== Hydration ==

	The strength of concrete depends on the reactions in its matrix and in particular on the growth of crystals. These are the result of the hydration process – the reaction between water and Portland cement. This process will continue almost indefinitely as long as there is water in the matrix. But a deficiency in water content will mean the crystals will not develop as they should and the concrete will:		The strength of concrete depends on the reactions in its matrix and in particular on the growth of crystals. These are the result of the hydration process – the reaction between water and Portland cement. This process will continue almost indefinitely as long as there is water in the matrix. But a deficiency in water content will mean the crystals will not develop as they should and the concrete will:
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	* May not achieve target durability.		* May not achieve target durability.

−	= Temperature =	+	== Temperature ==

−	Maintaining the correct temperature of the concrete is critical ~~– neither too hot nor too cold~~. It is currently thought that below 10°C sees a slow-down in hydration, while 4°C signals a virtual stop.	+	Maintaining the correct temperature of the concrete is critical. It is currently thought that below 10°C sees a slow-down in hydration, while 4°C signals a virtual stop. In contrast, a temperature that is too high speeds up the exothermic reaction causing temperature differentials within the concrete that can lead to cracking. This causes weaker strength development as the matrix crystals have not developed as they should have.

−	In contrast, a temperature that is too high speeds up the exothermic reaction causing temperature differentials within the concrete that can lead to cracking. This causes weaker strength development as the matrix crystals have not developed as they should have.	+	== Methods of curing concrete ==
−		+
−	= Methods of curing concrete =	+

	Curing aims to control the rapid loss of moisture from the setting concrete, so the aim is to provide a seal to prevent or slow down the rate of water evaporation. However, methods differ according to the type of structure or curing requirement. Some of the more common curing methods include:		Curing aims to control the rapid loss of moisture from the setting concrete, so the aim is to provide a seal to prevent or slow down the rate of water evaporation. However, methods differ according to the type of structure or curing requirement. Some of the more common curing methods include:
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	* Covering with damp sand or damp hessian – applied as soon as the concrete hardens otherwise surface damage may result.		* Covering with damp sand or damp hessian – applied as soon as the concrete hardens otherwise surface damage may result.
	* Sprinkling or spraying.		* Sprinkling or spraying.
−	* Ponding – can be used for horizontal surfaces such as slabs, roads, pavements etc. Involves placing small ponds of clay or sand across the surface which are filled with water. But water can leak out of the ponds and cause staining~~. Impractical~~ for large areas.	+	* Ponding – can be used for horizontal surfaces such as slabs, roads, pavements etc. Involves placing small ponds of clay or sand across the surface which are filled with water. But water can leak out of the ponds and cause staining, and it is impractical for large areas.
	* Steam curing.		* Steam curing.
	* Membrane curing.		* Membrane curing.
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	* Formwork – can provide a degree of protection but this will depend on when it is struck. If it is left in place for four days or more, there may be no need to provide further protection after the formwork is removed. Time will therefore be an important consideration, as will the degree of exposure of the concrete work. Even if formwork is used as a method of protection, the tops of walls and columns will still require curing.		* Formwork – can provide a degree of protection but this will depend on when it is struck. If it is left in place for four days or more, there may be no need to provide further protection after the formwork is removed. Time will therefore be an important consideration, as will the degree of exposure of the concrete work. Even if formwork is used as a method of protection, the tops of walls and columns will still require curing.

−	= Curing time =	+	== Curing time ==
		+
		+	The length of time for proper curing to take place will depend on specific conditions, national codes, etc. Flat concrete (e.g pavements, driveways, car parks etc) and structural concrete (e.g beams, columns, slabs, walls, retaining walls etc) typically require a seven-day curing time when temperatures are above 4°C. This usually allows the concrete to attain 70% of the specified compressive strength.

−	The length of time for proper curing to take place will depend on specific conditions, national codes, etc. Flat concrete (e.g pavements, driveways, car parks etc) and structural concrete (e.g beams, columns, slabs, walls, retaining walls etc) typically require a seven-day curing time when temperatures are above 4°C. This usually allows the concrete to attain 70% of the specified compressive strength. Curing time will depend on:	+	Curing time will depend on:

−	* Ambient weather conditions	+	* Ambient weather conditions.
−	* Mix proportions	+	* Mix proportions.
−	* Specified strength	+	* Specified strength.
−	* Size and shape of concrete being cast	+	* Size and shape of concrete being cast.

	= Related articles on Designing Buildings Wiki =		= Related articles on Designing Buildings Wiki =
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	* The properties of concrete.		* The properties of concrete.

−	[[Category:Construction_techniques]] [[Category:Products_/_components]]	+	[[Category:Construction_techniques]] [[Category:Products_/_components]] [[Category:DCN_Product_Knowledge]]

Editor: Created page with "= Introduction = Curing is a term applied to the chemical process that describes a change in the state of various materials, usually as they turn from liquid (or semi-liquid) to..."

2020-01-13T18:59:40Z

Created page with "= Introduction = Curing is a term applied to the chemical process that describes a change in the state of various materials, usually as they turn from liquid (or semi-liquid) to..."

New page

= Introduction =

Curing is a term applied to the chemical process that describes a change in the state of various materials, usually as they turn from liquid (or semi-liquid) to solid. It can apply to cement, concrete, adhesives, plasters, thermosetting plastics and other materials. It usually has important implications for strength development and therefore the construction process and so its effects should be considered carefully. One of the materials for which curing is critical is concrete.

= Concrete =

The curing time for cast-in-place concrete can be anything from three days to two weeks. The process of concrete setting involves an exothermic reaction, i.e heat is given off which requires proper curing. Ensuring the correct conditions for curing requires protecting the concrete from both high and low temperatures.

If freshly-poured concrete is not cured properly, it may:

* Set incorrectly and suffer fine cracking (‘crazing’) from shrinkage.
* Have an ultimate strength lower than the required design strength.

Both consequences could be catastrophic as cracks can allow the ingress of humidity and water which can cause corrosion of steel reinforcement; while failing to reach its design strength will mean a weaker concrete than designed with potential catastrophic consequences.

= Hydration =

The strength of concrete depends on the reactions in its matrix and in particular on the growth of crystals. These are the result of the hydration process – the reaction between water and Portland cement. This process will continue almost indefinitely as long as there is water in the matrix. But a deficiency in water content will mean the crystals will not develop as they should and the concrete will:

* Not reach its design strength.
* Not achieve volume stability.
* Not be resistant to freeze-thaw cycles.
* Have lower resistance to abrasion and scaling.
* May not achieve target durability.

= Temperature =

Maintaining the correct temperature of the concrete is critical – neither too hot nor too cold. It is currently thought that below 10°C sees a slow-down in hydration, while 4°C signals a virtual stop.

In contrast, a temperature that is too high speeds up the exothermic reaction causing temperature differentials within the concrete that can lead to cracking. This causes weaker strength development as the matrix crystals have not developed as they should have.

= Methods of curing concrete =

Curing aims to control the rapid loss of moisture from the setting concrete, so the aim is to provide a seal to prevent or slow down the rate of water evaporation. However, methods differ according to the type of structure or curing requirement. Some of the more common curing methods include:

* Covering concrete work with polythene sheeting, particularly for vertical elements e.g columns.
* Covering with damp sand or damp hessian – applied as soon as the concrete hardens otherwise surface damage may result.
* Sprinkling or spraying.
* Ponding – can be used for horizontal surfaces such as slabs, roads, pavements etc. Involves placing small ponds of clay or sand across the surface which are filled with water. But water can leak out of the ponds and cause staining. Impractical for large areas.
* Steam curing.
* Membrane curing.
* Spray-on compounds.
* Formwork – can provide a degree of protection but this will depend on when it is struck. If it is left in place for four days or more, there may be no need to provide further protection after the formwork is removed. Time will therefore be an important consideration, as will the degree of exposure of the concrete work. Even if formwork is used as a method of protection, the tops of walls and columns will still require curing.

= Curing time =

The length of time for proper curing to take place will depend on specific conditions, national codes, etc. Flat concrete (e.g pavements, driveways, car parks etc) and structural concrete (e.g beams, columns, slabs, walls, retaining walls etc) typically require a seven-day curing time when temperatures are above 4°C. This usually allows the concrete to attain 70% of the specified compressive strength. Curing time will depend on:

* Ambient weather conditions
* Mix proportions
* Specified strength
* Size and shape of concrete being cast

= Related articles on Designing Buildings Wiki =

* Admixture, additive or agent.
* Admixtures in concrete.
* Alkali-activated binder.
* Alkali-aggregate reaction (AAR).
* Alkali-silica reaction (ASR).
* Cast-in-place concrete.
* Compressive strength.
* Floor slab.
* Laitance.
* Portland cement.
* Precast concrete.
* Reinforced concrete.
* Screed.
* Testing concrete.
* The properties of concrete.

[[Category:Construction_techniques]] [[Category:Products_/_components]]