Stone materials¶
They are the materials that come from the stones or sands of nature.
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Stone properties¶
- Mechanical properties of stones
- They are hard materials, relatively brittle, and with sufficient mechanical resistance to be very practical in the construction of buildings and other similar structures.
- Density
In general, it is greater than that of water and varies from 1.5 kg/liter for sand to 2.8 kg/liter for slate, marble or granite.
Pumice or diatomite are exceptions with a very low density, less than that of water, as they are very porous.
- Response to light
Most stone materials are opaque and have very good resistance to solar radiation.
Some stones such as glass used in windows, quartz or sapphire used in watch faces are very transparent.
Other stone like porcelain are translucent.
- Stone manufacturing properties
Natural stones are not malleable or ductile, nor do they melt easily. They can be cut and polished to produce sheets and blocks.
Binders such as cement are liquid when mixed with water and can be easily molded before they harden.
Ceramic materials have a paste consistency that is very malleable but not very ductile. They can be easily shaped before firing.
Glass can be easily melted and acts like a very malleable and very ductile plastic material while hot. It can form very fine threads that serve as reinforcement to other materials (fiberglass).
- Stone conductivity
- Stone materials have very little thermal and electrical conductivity and resist high stresses and temperatures well. For this reason, glass and ceramics are used as electrical separators in high voltage lines and as refractory material in furnaces.
- Chemical properties of stones
The stone ones are very stable and resist well to acids and caustics and to oxidation and solar radiation.
The exception to this are limestone rocks and marble that are attacked by acids and gradually break down with the acid rain generated by pollution.
- Ecological properties of the stones
Stone materials are usually not very recyclable, except for glass, which can be recycled many times without loss of quality.
They are not toxic in nature, although the manufacture of cement produces many greenhouse gases. It is estimated that 8% of all CO2 emissions come from its manufacture.
Asbestos is highly carcinogenic, which is why its use and manufacture has been prohibited for years in Western countries.
Granite produces a radioactive and carcinogenic gas called radon. Inhabited areas that contain a lot of granite in the surroundings should take this into account in construction and use good ventilation systems.
Natural stones¶
- Marble
It has been used since ancient times to build buildings or carve sculptures. Today it is still used in construction to cover floors or walls with a luxurious appearance.
Marble is made of crystallized limestone, so it is not resistant to acids, which break it down.
Lysippos CC BY-SA 2.0 DE via Wikimedia Commons.¶
- Granite
It has been used since prehistoric times for construction and is highly valued for its great resistance to erosion and corrosion.
It has been widely used as a coating on public buildings and monuments. It is also used in everyday objects such as kitchen countertops.
As acid rain increases, granite is replacing marble in outdoor constructions.
Rojinegro81 CC BY-SA 3.0 via Wikimedia commons.¶
- Board
It is made up of flat and thin slabs or sheets that make it suitable for making flat panels used to cover roofs and, formerly, to write with chalk.
Dontworry CC BY-SA 3.0 via Wikimedia Commons.¶
- Limestone
It has been used since ancient times as a building element. Burgos Cathedral is built with limestone.
When burned in a kiln it produces lime, a fundamental component of gray cement.
Acid rain dissolves.
Great Pyramid of Giza. Completely covered with limestone.¶
Berthold Werner CC BY-SA 3.0 via Wikimedia Commons.- Sandstone
It is the most common sedimentary rock. It is composed of quartz grains and other particles joined by a natural cement (calcium carbonate or others).
It is used as a building material and in sharpening stones.
Sarranpa CC BY-SA 4.0 via Wikimedia Commons.¶
- Gravel and sands
- They are rocks of a small size. They are used together with cement to form concrete.
Clumping stones¶
They are industrially produced technical materials. They come in the form of a powder that, mixed with water, produces a paste that can be molded. Shortly after mixing with water, they harden and take on a stony consistency.
- And so
It is a white binder.
It has been used since prehistoric times to join and seal building stones. It is also used for lining and decorating walls and ceilings.
The finest grained plaster is called plaster.
- Cement
It is made up of limestone and calcined clays in an oven to which plaster is added to improve its properties. It is generally grey in color.
It is estimated that the annual production is more than 4000 million tons. Its main use is the production of concrete.
- Concrete
It is made up of cement mixed with sand and gravel.
Reinforced concrete has an internal structure of steel bars to improve its resistance.
It is used to make pillars and floors in buildings, roads, bridges, dams, ports, etc.
Dafran CC BY-SA 4.0 via Wikimedia Commons.¶
Ceramic stones¶
They are composed of a fine powder mixed with water, with a pasty appearance. Once modeled, it is baked to join the fine particles together by fusion.
- Clay
It is a sedimentary rock formed by very fine grains, less than 0.004mm.
It was the first ceramic made by humans and is still one of the cheapest and most widely used materials today.
It is used to make bricks, tiles, containers and to produce cement.
Siim Sepp CC BY-SA 3.0 via Wikimedia Commons.¶
- Crockery
It is made with clay mixed with sand. It is a porous material just like clay, so it is usually covered with an external varnish, the glaze, which crystallizes during firing, making the piece waterproof.
It is used to make tableware.
Lourdes Cardenal CC BY-SA 3.0 via Wikimedia Commons.¶
- Stoneware
It is a mixture of clay with materials such as silica that provide greater mechanical and firing resistance (tempering agents).
It is a very hard and waterproof material. It is mainly used in the manufacture of floor tiles.
- Porcelain
It is a ceramic material that is generally white, hard, impermeable, translucent, highly resistant to corrosion, thermal shock and a poor conductor of electricity.
Formed by kaolin powder, quartz and feldspar, it is the finest ceramic material and similar to glass.
It is used to make tableware, vases, electrical insulators, toilets, sinks, etc.
Glass¶
It is a material that is obtained by melting silica sand, limestone and sodium carbonate.
It is used to make tableware, bottles, window coverings, windshields, mirrors, lenses, laboratory equipment, etc.
Other materials (plaster sheets, plastic resins, etc.) can be reinforced with glass fibers so that they acquire greater mechanical resistance.
Questionnaires¶
Multiple choice questionnaire on stone materials.