Artificial stone

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Reduced, detailed replicas of Swedish rune stones made of artificial stone
The base, cross and body of the Wichert Court Cross in Ibbenbüren , erected in 1927, were cast from artificial stone.

As artificial stone (also alabastrite, cast marble, Marmorit, poly-Nature, Polyresin or Polystone; formerly also Pisésteine / earth stones; Art sandstone) are mineral- cement or resin-bonded denotes materials that with pictures of gravel , sand and rock powder are prepared. Artificial stones are used for window sills , stairs and floor coverings as well as wall tiles and floor tiles in the building industry.

Quartz composite materials for sinks , kitchen countertops and the like are not attributed to artificial stones by stonemasons, but are generally referred to as quartz composite or quartz material or with the respective trade name. In international trade, the quartz composite materials are called engineered stone .

Because artificial stone can be cast and the mixture can be adapted to requirements, objects can be produced that would cost many times over from other materials. A large number of the ornamental objects offered today such as sculptures, busts and garden figures are made of artificial stone. Artificial stone made from hydraulic binder has been around since 1000 BC. Known and found under the term Opus caementicium use. With the development of cement in the 19th century, the artificial stone industry, which was emerging in Germany, gave rise to the idea of ​​working stone from mortar. Models were England and France, where cement-bound building elements were already being experimented with at the beginning of the 19th century.

If artificial stones get their final shape through archetypes , they are not counted among the stone .

Demarcation

Artificial stone does not mean that it is an artistic work is, but that the stone artificially produced, and thus, in contrast to traditionally used stone from natural stone is.

Usually not referred to as artificial stones:

history

Artificial stone has been known since ancient times. From the middle of the 19th century, artificial stone was an inexpensive alternative to the natural stone product range. In the 19th century, the establishment of cement works was the basis for the manufacture of artificial stone. In Germany, the Ulm pharmacist Gustav Ernst Leube founded the first cement factory in 1838, which in 1840 produced floor slabs from so-called novel cement for the Ulm Minster . In the 1860s it was used to describe pisé stones (earth stones). Because of the poor quality of the early cements and insufficient knowledge of their processing, artificial stone outdoors quickly showed signs of cracks and weathering. In the 1860s / 70s, so-called Portland cement with good weather resistance prevailed. Joseph Aspdin received a patent for this in 1824 by mixing clay and lime as a binder and then heating them together.

Eugen Dyckerhoff , partner of the "Cementwaarenfabrik Lang 6 Cie." Since 1866, created further innovations with a new manufacturing process in which earth-moist concrete was compacted by ramming. Depending on the facing mortar, the hardened artificial stones had the appearance of natural stone. Often, weather-resistant limestone or marble stones, crushed to the size of sandstone, were used for the facing mortar. This made it possible to approximate the appearance of natural stone, especially since the artificial stone could be worked by stonemasons in the hardened state like natural stone. From the 1870s, the term artificial stone was mainly used for artificial sandstone. At the turn of the century, the term artificial stone became popular in construction. Artificial stone was also recognized because of the uniformity of the material. In contrast to natural stone, the material was characterized by its resistance to weathering and fire. Steel inserts made it possible to increase the load-bearing strength. From the Art Nouveau period , mineral-bound artificial stone was used on a larger scale as a substitute for natural stone for window and door frames, cornices, building ornaments and tombstones. In 1913 the stone, originally called artificial or cement artificial stone, was named "concrete stone" by the art committee of the German Concrete Association. Ulm is the actual center of German artificial stone production. From there, Steinfabrik Ulm AG also delivered to France and Belgium. Architects erected representative buildings with facade elements made of cast stone, often in reinforced concrete skeleton construction.

After the Second World War , artificial stone was produced on a large scale in the GDR until it was dissolved due to a lack of natural stones. In the Federal Republic of Germany, minerally bound artificial stone was poured in blocks using the vibration method and marketed. However, at the beginning of the 1970s, the demand for natural stone products rose continuously because natural stone became cheaper through imports and thus replaced artificial stone. Recently, there has been a slight increase in demand for artificial stone as a quartz composite material. At present, DIN 18 500 defines both cement-bound stones with a processed surface and those with an unprocessed surface, the visible surfaces of which are specially designed by the formwork as "concrete blocks".

Cement bond

Cement-bound artificial stones are and were made from two differently composed mineral mixtures. A mixture is made with stone chippings, the binding agent cement and cement paints with the addition of water. This mass is poured into prepared molds made of metal, wood or plaster and then tamped or shaken. A second mixture of concrete (cement and gravel) is produced plastically, introduced over the first mixture and, if this is expected, reinforced by the inlay of structural steel against static loads. After hardening, the visible surfaces are either scratched or sanded or, after the sanding process, filled against open pores. These artificial stones were and are used in the building industry as floor and stair coverings or for grave monuments, whereby the face of gravestones partly consisted of inlaid plates made of natural stone. The production of the cement-bound artificial stones took place in small batches.

In the 1960s there was an industrial process for the production of so-called slabs made of artificial stone (known under the trade mark Reko-Marmor). Artificial stone blocks were poured, which were formatted to the respective plate thickness by stone saws or gates . These plates were not reinforced and were mainly used for the base or edging of the grave.

Resin bond

Agglo marble and quartz material are trade names for artificial stones in which mineral binders such as cement are replaced by synthetic resins such as acrylates and epoxy resins . One also speaks of composite materials .

The artificial stone is created by combining ground rock powder and synthetic resin. This material is characterized by the low manufacturing costs, yet high quality and relative breaking strength. Artificial stone is widely used in the manufacture of decorations or fish hiding places for aquariums, in model making, for example, in miniature replicas of buildings, and in handicrafts in the manufacture of sculptures, statues, caskets, vases, souvenirs, advertising and fan articles, etc. Some mixtures are made also known as cold cast porcelain because they feel and behave similar to porcelain.

Due to the simplified processing and shaping compared to natural stone, wash basins and sinks and kitchen work surfaces are increasingly being made from composite materials. In particular with rather light and rather dark surfaces, discoloration can occur due to wear and tear of the surface as well as contact with coloring food and the like. make it visually noticeable. The synthetic resin can also be discolored through contact with hot pan bottoms, trays and the like.

Agglo marble

Marbles or limestones of different sizes and color pigments are usually used as aggregates for agglo-marble . It is initially produced by compacting by means of vibration, in which raw blocks of different sizes, such as 3.05 × 1.40 × 0.88 m, are cast and compacted. In this process, which the Italian company Breton developed in 1968, marble grains of different sizes and marble fragments are poured into a mold. The blocks then harden, and after hardening, the blocks are cut into raw panels with stone saws and processed like natural stones . The raw panels are primarily sawn to the appropriate dimensions to form floor panels. In addition, window sills and stairs are made of agglo-marble. In 1977 the Breton company patented a process for producing slabs from stone particles, polyester resins and pigments, which no longer required sawing into slabs.

The installation is carried out by stonemasons or tilers and using mortar technology. Due to the drop in prices of imported natural stones , which has persisted for years , the demand for this artificial stone has decreased. Agglo-marbles can imitate marbles deceptively real.

Quartz composite

According to the manufacturers, the aggregates for the quartz material developed in 1985 are up to 93 percent quartz powder plus color pigments and resin. Furthermore, pieces of glass and glittering particles can be mixed in. During production, the mass is poured into a form lined with paper and then compacted in a vacuum using a vibration seal process using massive presses. Finally, the mold is heated to 100 ° C in an oven for half an hour. In this process, the mixed mass polymerizes . Panels up to a size of 3.30 × 1.65 m can be produced. After cooling to ambient temperature, the quartz material can be ground and polished like natural stone with tools for hard stone. Usual panel thicknesses are 12, 20 and 30 mm.

Today, quartz material is mainly used for kitchen sinks and countertops. The material has a wear hardness that comes close to that of hard stone. In addition, individual colors and visual effects, such as partially glittering surfaces, can be produced according to customer requirements. Internationally positioned companies such as Cosentino from Spain, Quarella from Italy and Caesarstone from Israel, whose sheet material smaller companies offer their customers, are active on the market.

Application limits

Synthetic resin-bound artificial stone is sensitive to solvents and temperature. Hot pans must not be placed on kitchen worktops, as these damage the surfaces. In the case of light colors, discoloration can occur from food such as strongly coloring vegetables, which can be removed with bleach. In addition, no alkaline cleaning agents with a pH value above 12 may be used. The synthetic resin-bound building materials do not meet the values ​​of building material class A1 . To avoid damage, the care instructions of the manufacturer must be strictly observed when cleaning.

Depending on the ingredients, resin-bound natural stone can be polished. However, the polish is lost when the surfaces are stressed.

The influence of UV radiation can cause color changes in the polymers used.

Agglo-marble and quartz materials are artificial stones for which there is no valid DIN or EU standard. As a guide, the DIN for may cast stone are used, but only applies to cement-based artificial stone.

Today's difficulties with artificial stones

There is the problem of recognizing artificial stone at all, especially since natural and artificial stone were sometimes used in historical buildings. More than a hundred years after the building boom of the Wilhelminian era, facade elements made of artificial stone show damage in need of restoration. A systematic preoccupation with the existence and the possibilities of the preservation is largely missing.

literature

  • Geraldine Buchenau: Concrete and its growing role in the preservation of monuments. Early precast concrete parts for artificial stone facades in Baden-Würtemberg , Heidelberg 2018, ISSN 0342-0027
  • Hans Issel: artificial stone u. Mortar industry. Your latest products by machine production on floor and wall panels, bricks, hollow blocks, steps, roof tiles, pipes and posts. The mortar mix ratios as well as the type of regenerative aggregates; in addition, the mortar calculation according to mass and cost expenditure. , Published by Bernhard Friedrich Voigt, Leipzig 1922.
  • Sigmund Lehner: The artificial stones. A description of the representation of artificial stone masses, the raw materials, devices and machines . A. Hartleben's publishing house, Vienna / Leipzig 1927.
  • Karl Müller: Artificial stone construction, silent teacher for the entire artificial stone industry . Gommern 1905. New edition, Reprint-Verlag-Leipzig, Holzminden 2003, ISBN 3-8262-1314-9 .

Web links

Commons : Kunstein  - collection of images, videos and audio files

Individual evidence

  1. ↑ earth stones . In: Meyers Konversations-Lexikon 1885-1892, Volume 5, Pages 771-772
    This designation is not actually correct, because Piseesteine, Pisésteine, or rammed earth stones are artificial stones made from loamy earth by pressing or tamping.
  2. ↑ Engineered Stone , on natural stone magazine . Accessed July 31, 2019
  3. ↑ There are few exceptions: For example, around 1400, a number of sculptures were made from a so-called “cast stone mass”, in which rough blocks were cast and then sculpted. If artists use cement-bound masses to pour model forms, they speak of casts and not of sculptural work.
  4. ↑ earth stones . In: Meyers Konversations-Lexikon 1885-1892, Volume 5, Pages 771-772
    This designation is not actually correct, because Piseesteine, Pisésteine, or rammed earth stones are artificial stones made from loamy earth by pressing or tamping.
  5. ↑ Despite the dense consistency, care should be taken to ensure that delicate elements (e.g. arms and legs in statues) could easily break.
  6. ↑ Naturstein 2/2008, p. 22
  7. ↑ FRT guidelines for mineral floor coverings - cleaning methods and methods - cleaning, care and value retention , p. 17, European Research Association for Cleaning and Hygiene Technology eV, August 31, 2012