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Asbestos

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Info about Asbestos sheets and temperoary construction

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Asbestos

  1. 1. NAR-502 CONSTRUCTION AND MATERIALS-V Asbestos Products Temporary Construction
  2. 2. CONTENTS  ASBESTOS PRODUCTS • INTRODUCTION • TYPES OF ASBESTOS AND PRODUCTS • PROPERTIES • MANUFACTURING PROCESS  TEMPEROARY CONSTRUCTION • Introduction • Types of temporary construction • Shoring • Raking • Flying • Needle • 4. Reference
  3. 3. • ASBESTOS : • A highly heat- resistant fibrous silicate mineral that can be woven into fabrics, and is used in brake linings and in fire-resistance and insulating materials. • It was woven into fabric, and mixed with cement. • Its heat resistance, tensile strength and insulating properties. • ASBESTOS CEMENT: Asbestos cement is primarily a cement based product where about 10-15% W/W of asbestos fibers to reinforce cement.
  4. 4. Types of asbestos: There are six types of asbestos minerals, according to the Environmental Protection Agency (EPA): Chrysotile, Amosite, Crocidolite, Tremolite, Anthophyllite and Actinolite.  Chrysotile: •Approximately 90 percent of the asbestos used commercially in the world is chrysotile. •Its fibers are curly and longer than other asbestos types. Products: •Gasket •Cement •Insulation •Roofing material
  5. 5.  Amosite: • Amosite asbestos is primarily sourced in South Africa. • It often appears brown in color and its fibers are shorter and straighter than chrysotile fibers.  Products: • Cement sheets • Thermal Insulation • Roofing Products  Crocidilite: • This form of asbestos was used less commonly than other types of asbestos because it isn't as resistant to heat. • Commonly called blue asbestos. • It is considered the most harmful type of asbestos.  Products: • Ceiling tile • Fire protection • Insulation boards
  6. 6. • Tremolite : • Termolite is an amphibole. • Termolite fibers have been useful for commercial products. • They are strong, flexible, heat-resistant, and can be spun and woven into cloth.  Products: • Paints • Sealants • Insulation • Roofing materials • Actinolite :This mineral has straight-shaped fibers and is normally dark in color. • Actinolite was commonly combined with vermiculite to make insulation. It was also used in construction materials such as drywall and paint.
  7. 7. • Products: • Insulation Material • Gardening • Concrete materials used in construction • Structural fire-proofing  Anthophyllite: • Deposits are less common than other asbestos deposits. • Less of this mineral was used when compared to other forms of asbestos.
  8. 8. PROPERTIES OF ASBESTOS CEMENT PRODUCTS • Its tensile Strength surpass that of steel. • It has tremendous thermal stability, thermal and electrical resistance. • It is weather proof. • It absorbs moisture.
  9. 9. MANUFACTURING PROCESS • The products are processes in wet mode technically known as “Hatschek Process”. • Pressure packed polythene bags of chrysotile are opened by semi-automatic machine. • The binding material( cement and fly-ash) mixed with water to make slurry, which is fed to the Cylinder Vat through the Homogeniser feeding cone. • Cylinder rotates leaving thin film of stock deposited at its surface and film was transferred on to endless felt, which remains in contact with the top cover of the sieve cylinder. • Excess water was being removed from the felt by means of vacumn boxes placed under thee felt as it travels towards sheet formation drum in continuous operation until the sheet prepared to build up the desired thickness. • The sheets are then knifed along groove in the sheet formation drum roll and peeled to a moving rubber conveyor built, which collect the sheet clear from the machine.
  10. 10. • In the sheet corrugation and de moulding section, the wet plain sheets are corrugated by means of template. • The corrugated wet sheets stacked on a trolley and allowed for initially maturity of 15-18 hours • Finally at curing section, these sheet are stacked vertically and water poured on them here, sheets covers 25-28 days to develop optimum strength before being dispatched.

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