STONE MATERIALS

STONE MATERIALS

1. EXTRACTING AND PROCESSING STONE

   • Stone is extracted form natural deposits. Other materials, such as gravel and sand, are aggregates and they exist as fragment or grains or various sizes
     • Quarrying: Is a large stone blocks that are removed by the usin of various methods, a diamons wire saw is used to cut snmall pieces of stone to transport a procesing plants.
     • Processing: At the processing plant, the stone is processed as follows:

2. Natural stone

   • Limestone is a porous, off-white sedimentary rock that is usually white and may contain animal fossils.
   • Marble is a hard, dense metamorphic rock which is formed naturally from limestone. Marble is cool to the touch and well-known for its resistance to compression and extreme weather conditions.
   • Granite is an igneous rock that is composed mostly of quartz, feldspar and mica.
   • Slate is a dark blue or black metamorphic rock that is formed by the compression of fine clay.
   • Tuff is a porous rock that is formed by the cooling of volcanic ash and lava. It is a very good thermal insulator, so it is often used to build walls.

3. STONE BINDERS

   • Plaster is made from gypsum rock, which is crushed, heated and dehydrated. Plaster dissolves in water, creating a sticky paste that dries quickly.
   • Lime is produced by heating limestone to 900ºC, a process is called calcination. When lime is mixed with water, it forms a paste which solidifies quite easily.
   • Cement is a mixture of limestone and clay that has been crushed and heated to 1,250ºC. A small amount of plaster is added to make a grey powder that is mixed with water to form a paste.
   • Mortars are various mixtures of binders with sand and water. They can be either hydraulic or non-hydraulic.
   • ARTIFICIAL STONE
     • Concrete is a mixture of gravel, sand, water and cement that sets to form a rock-like material. This material has a uniform grey colour and takes the shape of the formwork that is used to mould it.
     • Fibre cement is composed of fibres covered with mortar. In the past, these fibres were made of asbestos, but that material has now been prohibited because it causes cancer and a disease called asbestosis.
     • Hempcrete bricks have become a popular substitute for ceramic bricks. Hempcrete is made of hemp fibre and soil, along with lime as a binder. After these ingredients are mixed, the hempcrete is pressed into brick moulds and left to dry.
     • Terrazzo is the most common artificial stone used in construction. It is made with a mixture of gravel and white cement and it is often used for floors. It can be installed as tiles or poured on-site and then polished.