Cast stone
Encyclopedia
Cast stone is defined as “a refined architectural concrete
building unit manufactured to simulate natural cut stone, used in unit masonry applications”. In the UK and Europe cast stone is defined as “any material manufactured with aggregate and cementitious binder, intended to resemble in appearance, and which may be used in a similar way to, natural stone”. Cast stone is a masonry
product, used as an architectural feature, trim, ornament or facing for buildings or other structures. Cast stone can be made from white and/or grey cements, manufactured or natural sands, carefully selected crushed stone
or well graded natural gravels and mineral coloring pigments to achieve the desired color and appearance while maintaining durable physical properties which exceed most natural cut building stones. Cast stone is an excellent replacement for natural cut limestone
, brownstone
, sandstone
, bluestone
, granite
, slate
, coral
rock, travertine
and other natural building stones.
Cast stone has been a prime building material for hundreds of years. The earliest known use of Cast stone dates about to the year 1138 and was seen at Carcassonne
, France, the city which contains the finest remains of medieval fortification in Europe. Cast stone was first used extensively in London in the 19th century and gained widespread acceptance in America in 1920.
Some researchers have even speculated that the Egyptian pyramids
were formed using a form of cast stone, rather than from cut blocks.
One of the earliest developments in the industry was Coade stone
, a fired ceramic, but most artificial stone consists of fine cement concrete placed to set in wooden, rubber lined fiberglass or iron moulds. It was cheaper and more uniform than natural stone, and widely used. In engineering projects, it had the advantage that transporting the bulk materials and casting them near the place of use was cheaper than transporting very large pieces of stone.
The first recorded commercial production of a cement based cast stone material in the format we know today, was in the late 1820s when Felix Austin went into business making artificial stone in New Road (now Euston Road), London, England. His material was not the same as the ceramic body used by Mrs. Coade, (although he is known to have copied old Coade stone
designs), but made from 'Portland cement
, broken natural stone, pounded marble and coarse sand' ('The Builder', 1868, now Building (magazine)
). Around 1840 Austin entered into partnership with John Seeley. Seeley had trained at the Royal Academy
Schools and also made an artificial stone, which he called ' artificial limestone ', before entering into partnership with Austin. In 1841 Austin and Seeley published their first catalogue, 'Collection of Ornaments at Austin & Seeley's Artificial Stone Works for Gardens, Parks and Pleasure Grounds'. The firm continued in production until about 1872.
Another well-known variety was Victoria stone, which is composed of finely crushed Mount Sorrel (Leicestershire) granite and Portland cement
, carefully mixed by machinery in the proportions of three to one, and filled into moulds of the required shape. When the blocks are set hard the moulds are loosened and the blocks placed in a solution of silicate of soda for about two weeks for the purpose of indurating and hardening them.
Many manufacturers turn out a material that is practically non-porous and is able effectually to resist the corroding influence of sea air or the impure atmosphere of large towns.
-based architectural precast concrete
product manufactured using high quality fine and coarse aggregate as its primary constituents. The use of a high percentage of fine aggregate creates a very smooth, consistent texture for the building elements being cast, resembling natural cut stone. Other ingredients such as chemical admixtures, pozzolan
s, and pigment
s also may be added.
Cast stone frequently is produced with a low water-to-cement ratio mixture with a "dry" (or "earth moist") consistency. The mixture is consolidated into a mould using an air-driven, or electric, tamping device
or vibration
under pressure
, which is much like the formation of natural sedimentary rock
. Products manufactured in this manner are referred to as vibrant-dry-tamped (VDT) cast stone. For cast stone mixtures produced with a slumpable consistency mixture, the concrete typically is consolidated using internal or external vibration applied to the production mould.
Over the last decade, new types of admixtures have been developed for VDT concrete products. These new admixtures do not normally work with "wet cast" concrete. These new plasticizer
s are more efficient than using air-entraining agents to increase compaction in VDT concrete. Some plasticizers have chemical properties that react with the cement to increase ultimate strengths of semi-dry concrete. Another important type of admixture for VDT concrete is integral waterproofing
formulas. Tests have shown that some of these integral waterproofing admixtures have improved strength by as much as 20% while reducing the absorption by 40%. The increased strength and reduced absorption results in improved freeze/thaw durability.
On recent commercial testing laboratory results the freeze-thaw for VDT concrete using integral waterproofing admixtures was 0.23% weight loss after 300 cycles. Air entraining agents have been the salvation of wet cast concrete as it pertains to its durability. Wet cast concrete with 4% to 6% entrained air normally can withstand numerous freeze-thaw cycles without failing. Other types of admixtures such as water-reducers, super plasticizers and the new self-compacting additives can add to improving the strength and durability of wet cast concrete products. Cast stone products manufactured by the wet cast method are required to meet the same standards as VDT cast products.
Today, the Industry Standard for physical properties and raw materials constituents is ASTM C 1364, the Standard Specification for Architectural Cast Stone. Membership in ASTM International
(founded in 1898 as the American Chapter of the International Association for Testing and Materials and most recently known as the American Society for Testing and Materials) exceeds 30,000 technical experts from more than 100 countries who comprise a worldwide standards forum. The ASTM method of developing standards has been based on consensus of both users and producers of all kinds of materials. The ASTM process ensures that interested individuals and organizations representing industry, academia, consumers, and governments alike, all have an equal vote in determining a standard's content.
In the UK and Europe it is more normal to use the Standard “BS 1217 Cast stone - Specification” from the BSI Group
, and the European Commission
's “Construction Products Regulations” legislation states that by mid 2013, all cast stone sold in Europe must be certified to this standard.
Concrete
Concrete is a composite construction material, composed of cement and other cementitious materials such as fly ash and slag cement, aggregate , water and chemical admixtures.The word concrete comes from the Latin word...
building unit manufactured to simulate natural cut stone, used in unit masonry applications”. In the UK and Europe cast stone is defined as “any material manufactured with aggregate and cementitious binder, intended to resemble in appearance, and which may be used in a similar way to, natural stone”. Cast stone is a masonry
Masonry
Masonry is the building of structures from individual units laid in and bound together by mortar; the term masonry can also refer to the units themselves. The common materials of masonry construction are brick, stone, marble, granite, travertine, limestone; concrete block, glass block, stucco, and...
product, used as an architectural feature, trim, ornament or facing for buildings or other structures. Cast stone can be made from white and/or grey cements, manufactured or natural sands, carefully selected crushed stone
Crushed stone
Crushed stone or angular rock is a form of construction aggregate, typically produced by mining a suitable rock deposit and breaking the removed rock down to the desired size using crushers...
or well graded natural gravels and mineral coloring pigments to achieve the desired color and appearance while maintaining durable physical properties which exceed most natural cut building stones. Cast stone is an excellent replacement for natural cut limestone
Limestone
Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....
, brownstone
Brownstone
Brownstone is a brown Triassic or Jurassic sandstone which was once a popular building material. The term is also used in the United States to refer to a terraced house clad in this material.-Types:-Apostle Island brownstone:...
, sandstone
Sandstone
Sandstone is a sedimentary rock composed mainly of sand-sized minerals or rock grains.Most sandstone is composed of quartz and/or feldspar because these are the most common minerals in the Earth's crust. Like sand, sandstone may be any colour, but the most common colours are tan, brown, yellow,...
, bluestone
Bluestone
Bluestone is a cultural or commercial name for a number of dimension or building stone varieties, including:*a feldspathic sandstone in the U.S. and Canada;*limestone in the Shenandoah Valley in the U.S...
, granite
Granite
Granite is a common and widely occurring type of intrusive, felsic, igneous rock. Granite usually has a medium- to coarse-grained texture. Occasionally some individual crystals are larger than the groundmass, in which case the texture is known as porphyritic. A granitic rock with a porphyritic...
, slate
Slate
Slate is a fine-grained, foliated, homogeneous metamorphic rock derived from an original shale-type sedimentary rock composed of clay or volcanic ash through low-grade regional metamorphism. The result is a foliated rock in which the foliation may not correspond to the original sedimentary layering...
, coral
Coral
Corals are marine animals in class Anthozoa of phylum Cnidaria typically living in compact colonies of many identical individual "polyps". The group includes the important reef builders that inhabit tropical oceans and secrete calcium carbonate to form a hard skeleton.A coral "head" is a colony of...
rock, travertine
Travertine
Travertine is a form of limestone deposited by mineral springs, especially hot springs. Travertine often has a fibrous or concentric appearance and exists in white, tan, and cream-colored varieties. It is formed by a process of rapid precipitation of calcium carbonate, often at the mouth of a hot...
and other natural building stones.
History
Carcassonne
Carcassonne is a fortified French town in the Aude department, of which it is the prefecture, in the former province of Languedoc.It is divided into the fortified Cité de Carcassonne and the more expansive lower city, the ville basse. Carcassone was founded by the Visigoths in the fifth century,...
, France, the city which contains the finest remains of medieval fortification in Europe. Cast stone was first used extensively in London in the 19th century and gained widespread acceptance in America in 1920.
Some researchers have even speculated that the Egyptian pyramids
Egyptian pyramids
The Egyptian pyramids are ancient pyramid-shaped masonry structures located in Egypt.There are 138 pyramids discovered in Egypt as of 2008. Most were built as tombs for the country's Pharaohs and their consorts during the Old and Middle Kingdom periods.The earliest known Egyptian pyramids are found...
were formed using a form of cast stone, rather than from cut blocks.
One of the earliest developments in the industry was Coade stone
Coade stone
Lithodipyra , or Coade stone, was ceramic stoneware that was often described as an artificial stone in the late 18th and early 19th centuries. It was used for moulding Neoclassical statues, architectural decorations and garden ornaments that were both of the highest quality and remain virtually...
, a fired ceramic, but most artificial stone consists of fine cement concrete placed to set in wooden, rubber lined fiberglass or iron moulds. It was cheaper and more uniform than natural stone, and widely used. In engineering projects, it had the advantage that transporting the bulk materials and casting them near the place of use was cheaper than transporting very large pieces of stone.
The first recorded commercial production of a cement based cast stone material in the format we know today, was in the late 1820s when Felix Austin went into business making artificial stone in New Road (now Euston Road), London, England. His material was not the same as the ceramic body used by Mrs. Coade, (although he is known to have copied old Coade stone
Coade stone
Lithodipyra , or Coade stone, was ceramic stoneware that was often described as an artificial stone in the late 18th and early 19th centuries. It was used for moulding Neoclassical statues, architectural decorations and garden ornaments that were both of the highest quality and remain virtually...
designs), but made from 'Portland cement
Portland cement
Portland cement is the most common type of cement in general use around the world because it is a basic ingredient of concrete, mortar, stucco and most non-specialty grout...
, broken natural stone, pounded marble and coarse sand' ('The Builder', 1868, now Building (magazine)
Building (magazine)
Building is one of the United Kingdom’s oldest business-to-business magazines, launched as The Builder in 1843 by Joseph Aloysius Hansom – architect of Birmingham Town Hall and designer of the Hansom Cab. The journal was renamed Building in 1966 as it is still known today. Building is the only UK...
). Around 1840 Austin entered into partnership with John Seeley. Seeley had trained at the Royal Academy
Royal Academy
The Royal Academy of Arts is an art institution based in Burlington House on Piccadilly, London. The Royal Academy of Arts has a unique position in being an independent, privately funded institution led by eminent artists and architects whose purpose is to promote the creation, enjoyment and...
Schools and also made an artificial stone, which he called ' artificial limestone ', before entering into partnership with Austin. In 1841 Austin and Seeley published their first catalogue, 'Collection of Ornaments at Austin & Seeley's Artificial Stone Works for Gardens, Parks and Pleasure Grounds'. The firm continued in production until about 1872.
Another well-known variety was Victoria stone, which is composed of finely crushed Mount Sorrel (Leicestershire) granite and Portland cement
Portland cement
Portland cement is the most common type of cement in general use around the world because it is a basic ingredient of concrete, mortar, stucco and most non-specialty grout...
, carefully mixed by machinery in the proportions of three to one, and filled into moulds of the required shape. When the blocks are set hard the moulds are loosened and the blocks placed in a solution of silicate of soda for about two weeks for the purpose of indurating and hardening them.
Many manufacturers turn out a material that is practically non-porous and is able effectually to resist the corroding influence of sea air or the impure atmosphere of large towns.
Physical properties
Today, cast stone is a Portland cementPortland cement
Portland cement is the most common type of cement in general use around the world because it is a basic ingredient of concrete, mortar, stucco and most non-specialty grout...
-based architectural precast concrete
Precast concrete
By producing precast concrete in a controlled environment , the precast concrete is afforded the opportunity to properly cure and be closely monitored by plant employees. Utilizing a Precast Concrete system offers many potential advantages over site casting of concrete...
product manufactured using high quality fine and coarse aggregate as its primary constituents. The use of a high percentage of fine aggregate creates a very smooth, consistent texture for the building elements being cast, resembling natural cut stone. Other ingredients such as chemical admixtures, pozzolan
Pozzolan
A pozzolan is a material which, when combined with calcium hydroxide, exhibits cementitious properties. Pozzolans are commonly used as an addition to Portland cement concrete mixtures to increase the long-term strength and other material properties of Portland cement concrete, and in some cases...
s, and pigment
Pigment
A pigment is a material that changes the color of reflected or transmitted light as the result of wavelength-selective absorption. This physical process differs from fluorescence, phosphorescence, and other forms of luminescence, in which a material emits light.Many materials selectively absorb...
s also may be added.
Cast stone frequently is produced with a low water-to-cement ratio mixture with a "dry" (or "earth moist") consistency. The mixture is consolidated into a mould using an air-driven, or electric, tamping device
Tamp
A tamp is a device used to compact or flatten an aggregate or other powdered or granular material, typically to make it resistant to further compression or simply to increase density....
or vibration
Vibration
Vibration refers to mechanical oscillations about an equilibrium point. The oscillations may be periodic such as the motion of a pendulum or random such as the movement of a tire on a gravel road.Vibration is occasionally "desirable"...
under pressure
Pressure
Pressure is the force per unit area applied in a direction perpendicular to the surface of an object. Gauge pressure is the pressure relative to the local atmospheric or ambient pressure.- Definition :...
, which is much like the formation of natural sedimentary rock
Sedimentary rock
Sedimentary rock are types of rock that are formed by the deposition of material at the Earth's surface and within bodies of water. Sedimentation is the collective name for processes that cause mineral and/or organic particles to settle and accumulate or minerals to precipitate from a solution....
. Products manufactured in this manner are referred to as vibrant-dry-tamped (VDT) cast stone. For cast stone mixtures produced with a slumpable consistency mixture, the concrete typically is consolidated using internal or external vibration applied to the production mould.
Over the last decade, new types of admixtures have been developed for VDT concrete products. These new admixtures do not normally work with "wet cast" concrete. These new plasticizer
Plasticizer
Plasticizers or dispersants are additives that increase the plasticity or fluidity of the material to which they are added; these include plastics, cement, concrete, wallboard, and clay. Although the same compounds are often used for both plastics and concretes the desired effects and results are...
s are more efficient than using air-entraining agents to increase compaction in VDT concrete. Some plasticizers have chemical properties that react with the cement to increase ultimate strengths of semi-dry concrete. Another important type of admixture for VDT concrete is integral waterproofing
Waterproofing
Waterproof or water-resistant describes objects relatively unaffected by water or resisting the ingress of water under specified conditions. Such items may be used in wet environments or under water to specified depths...
formulas. Tests have shown that some of these integral waterproofing admixtures have improved strength by as much as 20% while reducing the absorption by 40%. The increased strength and reduced absorption results in improved freeze/thaw durability.
On recent commercial testing laboratory results the freeze-thaw for VDT concrete using integral waterproofing admixtures was 0.23% weight loss after 300 cycles. Air entraining agents have been the salvation of wet cast concrete as it pertains to its durability. Wet cast concrete with 4% to 6% entrained air normally can withstand numerous freeze-thaw cycles without failing. Other types of admixtures such as water-reducers, super plasticizers and the new self-compacting additives can add to improving the strength and durability of wet cast concrete products. Cast stone products manufactured by the wet cast method are required to meet the same standards as VDT cast products.
Today, the Industry Standard for physical properties and raw materials constituents is ASTM C 1364, the Standard Specification for Architectural Cast Stone. Membership in ASTM International
ASTM International
ASTM International, known until 2001 as the American Society for Testing and Materials , is an international standards organization that develops and publishes voluntary consensus technical standards for a wide range of materials, products, systems, and services...
(founded in 1898 as the American Chapter of the International Association for Testing and Materials and most recently known as the American Society for Testing and Materials) exceeds 30,000 technical experts from more than 100 countries who comprise a worldwide standards forum. The ASTM method of developing standards has been based on consensus of both users and producers of all kinds of materials. The ASTM process ensures that interested individuals and organizations representing industry, academia, consumers, and governments alike, all have an equal vote in determining a standard's content.
In the UK and Europe it is more normal to use the Standard “BS 1217 Cast stone - Specification” from the BSI Group
BSI Group
BSI Group, also known in its home market as the British Standards Institution , is a multinational business services provider whose principal activity is the production of standards and the supply of standards-related services.- History :...
, and the European Commission
European Commission
The European Commission is the executive body of the European Union. The body is responsible for proposing legislation, implementing decisions, upholding the Union's treaties and the general day-to-day running of the Union....
's “Construction Products Regulations” legislation states that by mid 2013, all cast stone sold in Europe must be certified to this standard.