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Questions and Answers
Is gypsum a hydraulic binder?
False
Pure gypsum is a hard crystalline mineral that cannot be scratched by a fingernail.
False
Low burning type of gypsum is manufactured at a temperature of about 160°C.
True
Extra strong gypsum is used for the manufacture of moulds.
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Gypsum is heated to a temperature up to 200°C during the manufacturing process.
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Describe the unique property of gypsum when heated and the subsequent behavior when water is added to the powder.
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How is low burning type gypsum manufactured and at what temperature?
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What is the classification of gypsum binders based on burning and their respective manufacturing processes?
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How is extra strong gypsum manufactured and what is its specific use?
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What are the initial steps in the manufacture of gypsum?
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Pure gypsum is a ______ crystalline mineral and is very soft that it can be scratched by a finger nail.
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Gypsum has a unique property of ______. When heated it loses the combined water and easily turns into powder. When adding water to the powder it can easily be shaped and moulded, and in a short time it hardens.
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Gypsum binders are classified according to burning: 1- Low burning type is manufactured by heating dehydrated gypsum to a temperature of about ______ °C.
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Gypsum may also be classified according to strength: 1- Low strength gypsum — Obtained by heating natural gypsum rock at normal pressure, the resultant gypsum is very hygroscopic (60–65%) and ______ (40%).
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Gypsum manufacture starts with 1- Extracting the raw gypsum material and then grinding into a fine powder. 2- Heated to a temperature up to 200 °C in special furnaces where they can control the temperature, here the ______ has separated in whole or in part of calcium sulphate, which represents the water element basis.
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Study Notes
Properties of Gypsum
- Pure gypsum is a hard crystalline mineral that cannot be scratched by a fingernail.
- Pure gypsum is a soft mineral that can be scratched by a fingernail.
Unique Property of Gypsum
- When heated, gypsum loses the combined water and easily turns into powder.
- When water is added to the powder, it can easily be shaped and molded, and in a short time it hardens.
Manufacturing of Low Burning Type Gypsum
- Low burning type gypsum is manufactured by heating dehydrated gypsum to a temperature of about 160°C.
Classification of Gypsum Binders
- Gypsum binders are classified according to burning: Low burning type and Extra strong type.
- Gypsum binders can also be classified according to strength: Low strength gypsum and Extra strong gypsum.
Extra Strong Gypsum
- Extra strong gypsum is used for the manufacture of molds.
- Extra strong gypsum is manufactured by heating gypsum to a temperature up to 200°C.
Initial Steps in Gypsum Manufacture
- Extracting the raw gypsum material.
- Grinding the raw material into a fine powder.
- Heating the powder to a temperature up to 200°C in special furnaces.
- At this stage, the water element (calcium sulphate) is separated in whole or in part.
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Description
Test your knowledge on the definitions and properties of gypsum and lime. Learn about gypsum's unique property of molding and its behavior when heated or mixed with water.
