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Quicklime vs. Hydrated Lime: What's the Difference?

Edited by Aimie Carlson || By Janet White || Published on December 10, 2023
Quicklime is calcium oxide (CaO), made by heating limestone; hydrated lime is calcium hydroxide (Ca(OH)₂), made by adding water to quicklime.

Key Differences

Quicklime, chemically known as calcium oxide, is a caustic alkaline substance produced by heating limestone in a kiln. Hydrated lime, or calcium hydroxide, is created when water is added to quicklime, leading to a less caustic but still alkaline substance.
Quicklime has a high melting point and is used in industrial processes like steel making and waste treatment. Hydrated lime, being more stable and less reactive, is used in building, agriculture, and water treatment.
In construction, quicklime is used for soil stabilization and as a component in cement. Hydrated lime, due to its stability and plasticity, is preferred in plaster, mortar, and whitewash.
Quicklime reacts vigorously with water, releasing a significant amount of heat, making it hazardous to handle without proper safety measures. Hydrated lime, though safer to handle, still requires caution as it can cause skin and eye irritation.
Quicklime is more caustic and has a higher pH than hydrated lime, making it more effective in certain industrial applications. Hydrated lime, with a lower pH, is more suitable for environmental and agricultural uses.

Comparison Chart

Chemical Formula



Produced by heating limestone
Created by adding water to quicklime


Steel making, soil stabilization
Plaster, mortar, agriculture


Highly reactive with water
Less reactive, safer to handle

PH Level

Higher pH, more caustic
Lower pH, less caustic

Quicklime and Hydrated Lime Definitions


A compound used for environmental applications like waste treatment.
Quicklime helped neutralize the acidic industrial waste.

Hydrated Lime

Calcium hydroxide, commonly used in building materials.
The masons used hydrated lime for the new mortar mix.


A material used in building for soil stabilization.
Quicklime was essential in the road construction project.

Hydrated Lime

A less reactive form of lime used in environmental applications.
Hydrated lime was utilized in the water purification process.


A white, caustic, alkaline substance consisting of calcium oxide.
Quicklime was used to improve the soil's pH balance.

Hydrated Lime

A dry, colorless crystalline powder used in various applications.
Hydrated lime was added to the paint to enhance its durability.


Calcium oxide formed by calcining limestone.
The kiln produced quicklime for industrial applications.

Hydrated Lime

An alkaline material used in construction and manufacturing.
Hydrated lime was chosen for plastering the historic building.


A reactive chemical used in construction and industry.
Quicklime's heat generation is crucial in metal processing.

Hydrated Lime

A compound with a variety of uses in agriculture and water treatment.
Hydrated lime proved effective in adjusting the soil acidity.


See calcium oxide.


Calcium oxide, which is produced by heating (calcining) limestone and gives slaked lime on treatment with water.


(transitive) To treat with quicklime.


Calcium oxide; unslacked lime; - so called because when wet it develops great heat. See 4th Lime, 2.


A white crystalline oxide used in the production of calcium hydroxide


What are the main uses of quicklime?

Quicklime is used in steel making, soil stabilization, and waste treatment.

Is hydrated lime safer than quicklime?

Yes, it’s less caustic and reactive, though still requires caution.

Why is hydrated lime used in construction?

Its stability and plasticity make it suitable for plaster and mortar.

How is hydrated lime made?

Hydrated lime is made by adding water to quicklime, forming calcium hydroxide.

Can hydrated lime be used in agriculture?

Yes, it's used to adjust soil pH and improve soil quality.

Does quicklime have environmental uses?

Yes, it's used in environmental cleanup and waste treatment.

Can quicklime be used in water treatment?

Yes, but it's more common to use hydrated lime due to safety and control.

What is quicklime?

Quicklime is calcium oxide, a caustic substance produced by heating limestone.

Is quicklime dangerous to handle?

Yes, it reacts vigorously with water and can be hazardous.

What safety measures are needed for handling quicklime?

Protective gear, including gloves and eye protection, is necessary.

Is quicklime used in agriculture?

It can be, but hydrated lime is more commonly used due to its safety.

Can hydrated lime be used in food processing?

Yes, it's used in some food processing applications.

What industries use quicklime?

Steel, construction, and environmental management industries use quicklime.

How does hydrated lime affect soil?

It increases soil alkalinity, making it more suitable for certain crops.

How is quicklime stored?

It should be stored in a dry, airtight container to prevent reaction with moisture.

Why is hydrated lime used in water purification?

It helps in removing impurities and adjusting the pH of water.

What's the difference in pH between quicklime and hydrated lime?

Quicklime has a higher pH and is more caustic compared to hydrated lime.

Can quicklime be converted into hydrated lime?

Yes, by adding water to quicklime, it becomes hydrated lime.

Are there any health risks associated with hydrated lime?

It can cause skin and eye irritation, so proper handling is important.

Can both quicklime and hydrated lime be used in the same applications?

Sometimes, but they have different properties and safety considerations.
About Author
Written by
Janet White
Janet White has been an esteemed writer and blogger for Difference Wiki. Holding a Master's degree in Science and Medical Journalism from the prestigious Boston University, she has consistently demonstrated her expertise and passion for her field. When she's not immersed in her work, Janet relishes her time exercising, delving into a good book, and cherishing moments with friends and family.
Edited by
Aimie Carlson
Aimie Carlson, holding a master's degree in English literature, is a fervent English language enthusiast. She lends her writing talents to Difference Wiki, a prominent website that specializes in comparisons, offering readers insightful analyses that both captivate and inform.

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