Stone Materials: Types, Properties, and Uses

STONE MATERIALS: Stone materials are often used for construction because they are strong, durable and very resistant to weather conditions.

1.1. Extracting and processing stone: Stone is extracted from natural deposits. Some types exist as large blocks, such as marble and granite from quarries, which must be cut into smaller pieces. Other materials, such as gravel and sand, are aggregates.

1.2. Natural stone: -Limestone is a porous sedimentary rock. It is often used for sculptures and buildings, as well as for breakwaters in ports. -Limestone is used to produce lime and cement.

-Marble is a hard rock. Marble is cool to the touch and well-known for its resistance to compression and extreme weather conditions. Marble comes in a variety of colors and has a shiny finish when it is polished. It is often used to make sculptures, decorations, columns, floors, walls, and kitchen countertops.

-Granite is very resistant to impacts, compression, and erosion. It is also found in a wide variety of color combinations. Granite is typically used for floors, walls, kitchen countertops, and sculptures.

-Slate is a dark blue or black rock. It is not only hard but also waterproof, due to its dense, compact nature. Slate is traditionally used for roofs and pavements.

-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. In the Canary Islands, traditional architecture often combines tuff with white limestone.

1.3. Stone binders: When water is added to binders, there is an exothermic chemical reaction that leads to a setting process. After stone binders have set, they are hard and resistant.

-Plaster dissolves in water, creating a sticky paste that dries quickly. After it has dried, plaster is resistant to compression and fire. Uses: Lining for walls and ceilings, prefabricated plasterboard for walls and ceilings, prefabricated moldings, and sculptures.

-When lime is mixed with water, it forms a paste that solidifies quite easily. Uses: Whitewashing for walls and in mixtures with other building materials.

-Cement is a mixture of limestone and clay that has been crushed and heated to 1250°C. A small amount of plaster is added to make a gray powder that is mixed with water to form a paste. When the paste dries and sets, it becomes very hard and resistant. Uses: Pipes, bricks and blocks, mortar, and mixtures with other building materials.

-Mortars are various mixtures of binders with sand and water. They can be either hydraulic or non-hydraulic.

-Hydraulic mortars can set underwater, so they are very useful for building.

-Non-hydraulic mortars can only set in the open air. Uses: Binding bricks, foundations, and bridges.

1.4. Artificial stone: -Concrete is a mixture of gravel, sand, water, and cement that sets a rock-like material. Concrete is very resistant to pressure but not to traction. However, when concrete is used for structural purposes, a framework of steel bars (rebar) can be added. The result is a composite material called reinforced concrete, which is resistant to pressure, traction, and torsion. -Fiber cement is composed of fibers covered with mortar. In the past, these fibers were made of asbestos, but that material has now been prohibited because it causes cancer and a disease called asbestosis. Instead of asbestos, we now use fiberglass or cellulose fiber to make fiber cement. -Hempcrete bricks have become a popular substitute for ceramic bricks. Hempcrete is made of hemp fiber and soil, along with lime as a binder. After these ingredients are mixed, the hempcrete is pressed into brick molds and left to dry. As a result, very little energy is needed to make hempcrete bricks. They are strong and resistant. -Terrazzo is the most common artificial stone used in construction. It is made with a mixture of gravel and white cement and is often used for floors. It can be installed as tiles or poured on-site and then polished. A special type of terrazzo is used to make benches, fountains, window ledges, and rain gutters. 2. CERAMIC MATERIALS: 2.1. General properties:

COARSE CERAMICS

Types

Uses

Terracotta is made with ordinary clay that is usually a matte red color. It is hard, rough, and fragile.

Bricks, roof tiles, pottery such as jars, vases, flower pots, and jugs.

Earthenware is made from a mixture of white clay, silica, and feldspar. It is fine and smooth, as well as hard.

Crockery, decorative objects, and bathroom tiles.

Refractory ceramics are made with baked clay and metal oxides. They can resist temperatures up to 3000ºC.

Blast furnace linings, electrical and electronic components.

FINE CERAMICS

TYPES

USES

Stoneware, which is made from refractory clay, has a glass-like appearance. It is very compactable and hard enough to scratch glass.

Tiles (azulejos).

Porcelain is made with a special white clay. It is transparent, translucent, compact, acid-resistant, and hard enough to scratch glass.

Tableware, decorative objects, bathroom fixtures, laboratory materials for the chemical industry.

3. GLASS

Glass is a transparent or translucent material that can take on different colors. It is hard and smooth but also fragile.

3.1. Glass forming techniques

Glass is made with a mixture of sand, quartz, lime, and soda. This mixture is melted in a kiln at temperatures of more than 1400ºC. The result is a soft, hot paste that can be shaped with a variety of techniques.

-Automatic blow molding: Hot glass is poured into a hollow mold with the required shape. The mold is closed, and then compressed air is used to push the glass against the sides of the mold. After the glass has cooled, the mold is opened, and the glass object is taken out. Uses: Bottles, jars, bulbs, and glasses.

-Glass casting: Hot glass is poured into a mold and allowed to cool until it solidifies. Hollow objects are made by using two molds and joining them afterward. For this reason, glass objects made by casting have seams where two parts were joined together. Uses: Ashtrays, containers, and glass bricks for construction.

-Floating: Hot glass is poured into a tank that contains liquid metal, such as tin. The glass floats and spreads out in a thin sheet because the metal is denser than the glass. Then the sheet of glass is moved into an annealing kiln by a system of rollers. Finally, the glass is heated again and allowed to cool slowly. Uses: Plate glass between 3mm and 18mm thick (the same as stretching).

-Calendering and lamination: Hot glass goes through a system of rollers which have either a textured or a smooth surface. This compression process is called calendaring. Uses: safety glass.