Terrazzo
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Terrazzo is a composite material, poured in place or precast, which is used for floor and wall treatments. It consists of chips of
marble Marble is a metamorphic rock composed of recrystallized carbonate minerals, most commonly calcite or dolomite. Marble is typically not foliated (layered), although there are exceptions. In geology, the term ''marble'' refers to metamorphose ...
,
quartz Quartz is a hard, crystalline mineral composed of silica ( silicon dioxide). The atoms are linked in a continuous framework of SiO4 silicon-oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical ...
,
granite Granite () is a coarse-grained ( phaneritic) intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly cools and solidifies under ...
,
glass Glass is a non-crystalline, often transparent, amorphous solid that has widespread practical, technological, and decorative use in, for example, window panes, tableware, and optics. Glass is most often formed by rapid cooling ( quenching ...
, or other suitable material, poured with a
cementitious A cement is a binder, a chemical substance used for construction that sets, hardens, and adheres to other materials to bind them together. Cement is seldom used on its own, but rather to bind sand and gravel ( aggregate) together. Cement mi ...
binder (for chemical binding),
polymer A polymer (; Greek '' poly-'', "many" + ''-mer'', "part") is a substance or material consisting of very large molecules called macromolecules, composed of many repeating subunits. Due to their broad spectrum of properties, both synthetic a ...
ic (for physical binding), or a combination of both. Metal strips often divide sections, or changes in color or material in a pattern. Additional chips may be sprinkled atop the mix before it sets. After it is cured it is ground and polished smooth or otherwise finished to produce a uniformly textured surface. "Terrazzo" is also often used to describe any pattern similar to the original terrazzo floors.


History


Terrazzo proper

Although the history of terrazzo can be traced back to the ancient
mosaic A mosaic is a pattern or image made of small regular or irregular pieces of colored stone, glass or ceramic, held in place by plaster/mortar, and covering a surface. Mosaics are often used as floor and wall decoration, and were particularly pop ...
s of Egypt, its more recent predecessors come from Italy. The form of terrazzo used today derives partly from the 18th century ''pavimento alla Veneziana'' ( Venetian pavement) and the cheaper ''seminato.'' ''Pavimento alla Veneziana'' had workers place marble fragments next to each other in a mortar base. Terrazzo is also related to the technique ''seminato'' for which workers tossed larger marble chips into the cement that was then ground and polished. Together, these methods create the generic form of terrazzo that involves pieces of stone that are bonded to a cement bed. Terrazzo was first introduced in the United States in the late 1890s, but did not achieve popularity until the 1920s. Until then it was hand polished with a long handled tool called a ''galera''. Due to its likelihood of cracking, terrazzo was used at a small scale in comparison to the large expanses we see today. Two inventions resulted in its rise in popularity: divider strips and the electric grinding machine. The invention of divider strips by L. Del Turco and Bros. in 1924 contained the cracking of terrazzo by allowing the material greater space to expand and shrink after installation. This invention made terrazzo a durable and reliable material in addition to allowing for further design work within the floor. Installers use the dividing strips as guides when they work with different colored terrazzo. The electric grinding machine and mechanization of the production process cut down on costs and time making terrazzo an affordable flooring option.
Art Deco Art Deco, short for the French ''Arts Décoratifs'', and sometimes just called Deco, is a style of visual arts, architecture, and product design, that first appeared in France in the 1910s (just before World War I), and flourished in the Unite ...
and Moderne styles from the 1920s to 1940s favored terrazzo with the dividers allowing for straight or curved lines that increased the decorative potential. The popularity of terrazzo led to an increase in installers in the 1920s. The National Terrazzo and Mosaic Organization was formed in 1931 to further professionalize the practice of terrazzo installation. One of the best-known examples of terrazzo is the Hollywood Walk of Fame. Created in 1958, the walk honors celebrities in the form of a terrazzo star that displays their name.


Archaeological use of the term

Archaeologists have adopted the term ''terrazzo'' to describe the floors of early
Neolithic The Neolithic period, or New Stone Age, is an Old World archaeological period and the final division of the Stone Age. It saw the Neolithic Revolution, a wide-ranging set of developments that appear to have arisen independently in several p ...
buildings (
PPNA Pre-Pottery Neolithic A (PPNA) denotes the first stage of the Pre-Pottery Neolithic, in early Levantine and Anatolian Neolithic culture, dating to years ago, that is, 10,000–8,800 BCE. Archaeological remains are located in the Levantine and U ...
and
PPNB Pre-Pottery Neolithic B (PPNB) is part of the Pre-Pottery Neolithic, a Neolithic culture centered in upper Mesopotamia and the Levant, dating to years ago, that is, 8800–6500 BC. It was typed by British archaeologist Kathleen Kenyon duri ...
, ca. 9,000–8,000 BC) in
Western Asia Western Asia, West Asia, or Southwest Asia, is the westernmost subregion of the larger geographical region of Asia, as defined by some academics, UN bodies and other institutions. It is almost entirely a part of the Middle East, and includes Ana ...
constructed of burnt
lime Lime commonly refers to: * Lime (fruit), a green citrus fruit * Lime (material), inorganic materials containing calcium, usually calcium oxide or calcium hydroxide * Lime (color), a color between yellow and green Lime may also refer to: Botany ...
and clay, colored red with ochre and polished. The embedded crushed limestone gives it a slightly mottled appearance. The use of fire to produce burnt lime, which was also used for the
hafting Hafting is a process by which an artifact, often bone, stone, or metal is attached to a ''haft'' (handle or strap). This makes the artifact more useful by allowing it to be shot (arrow), thrown by hand (spear), or used with more effective levera ...
of implements, predates production of fired pottery by almost a thousand years. In the early Neolithic settlement of
Çayönü Çayönü Tepesi is a Neolithic settlement in southeastern Turkey which prospered from circa 8,630 to 6,800 BC. It is located forty kilometres north-west of Diyarbakır, at the foot of the Taurus mountains. It lies near the Boğazçay, a trib ...
in eastern
Turkey Turkey ( tr, Türkiye ), officially the Republic of Türkiye ( tr, Türkiye Cumhuriyeti, links=no ), is a list of transcontinental countries, transcontinental country located mainly on the Anatolia, Anatolian Peninsula in Western Asia, with ...
about of terrazzo floors have been uncovered. The floors of the PPN B settlement of
Nevalı Çori Nevalı Çori ( tr, Nevali Çori, ku, Newala Çorî) was an early Neolithic settlement on the middle Euphrates, in Şanlıurfa Province, Southeastern Anatolia, Turkey. The site is known for having some of the world's oldest known temples and mon ...
measure about . They are thick, and contain about 10–15% lime. These floors are almost impenetrable to moisture and very durable, but their construction involved a high input of energy. Gourdin and Kingery (1975) estimate that the production of any given amount of lime requires about five times that amount of wood. Recent experiments by Affonso and Pernicka have shown that only twice the amount is needed, but that would still amount to 4.5 metric tonnes of dry wood for the floors in Çayönü. Other sites with terrazzo floors include Nevalı Çori,
Göbekli Tepe Göbekli Tepe (, "Potbelly Hill"; known as ''Girê Mirazan'' or ''Xirabreşkê'' in Kurdish) is a Neolithic archaeological site in the Southeastern Anatolia Region of Turkey. Dated to the Pre-Pottery Neolithic, between 9500 and 8000 BCE, the ...
,
Jericho Jericho ( ; ar, أريحا ; he, יְרִיחוֹ ) is a Palestinian city in the West Bank. It is located in the Jordan Valley, with the Jordan River to the east and Jerusalem to the west. It is the administrative seat of the Jericho Gove ...
, and
Kastros Kastros is an early Neolithic settlement in Cyprus. Location It lies at the north-easternmost tip of the Karpasia Peninsula ( Cape Apostolos Andreas), about 4 km north of Apostolos Andreas Monastery. The settlement is situated on a little p ...
(
Cyprus Cyprus ; tr, Kıbrıs (), officially the Republic of Cyprus,, , lit: Republic of Cyprus is an island country located south of the Anatolian Peninsula in the eastern Mediterranean Sea. Its continental position is disputed; while it is ge ...
).


Production

Terrazzo artisans create walls, floors,
patio A patio (, from es, patio ; "courtyard", "forecourt", "yard", "little garden") is an outdoor space generally used for dining or recreation that adjoins a structure and is typically paved. In Australia the term is expanded to include roofed str ...
s, and panels by exposing marble chips and other fine aggregates on the surface of finished
concrete Concrete is a composite material composed of fine and coarse aggregate bonded together with a fluid cement (cement paste) that hardens (cures) over time. Concrete is the second-most-used substance in the world after water, and is the most wid ...
or
epoxy Epoxy is the family of basic components or cured end products of epoxy resins. Epoxy resins, also known as polyepoxides, are a class of reactive prepolymers and polymers which contain epoxide groups. The epoxide functional group is also coll ...
-resin. Much of the preliminary work of terrazzo workers is similar to that of cement masons. Marble-chip, cementitious terrazzo requires three layers of materials. First, cement masons or terrazzo workers build a solid, level concrete foundation that is deep. After the forms are removed from the foundation, workers add a layer of sandy concrete. Before this layer sets, terrazzo workers partially embed metal divider strips in the concrete wherever there is to be a joint or change of color in the terrazzo. For the final layer, terrazzo workers blend and place into each of the panels a fine marble chip mixture that may be color-pigmented. While the mixture is still wet, workers toss additional marble chips of various colors into each panel and roll a weighted roller () over the entire surface. In the 1970s,
polymer A polymer (; Greek '' poly-'', "many" + ''-mer'', "part") is a substance or material consisting of very large molecules called macromolecules, composed of many repeating subunits. Due to their broad spectrum of properties, both synthetic a ...
-based terrazzo was introduced and is called thin-set terrazzo. Initially polyester and
vinyl ester left, 144px, Vinyl acetate is a commercially important monomer that is classified as a vinyl ester (i.e. an ester of vinyl alcohol). Vinyl ester refers to esters formerly derived from vinyl alcohol. Commercially important examples of these mono ...
resins were used as the binder resin. Today, most of the terrazzo installed is epoxy terrazzo. The advantages of this material over cementitious terrazzo include a wider selection of colors, installation thickness, lighter weight, faster installation, impermeable finish, higher strength, and less susceptibility to cracking. The disadvantage of epoxy resin–based terrazzo is that it can only be used for interior, not exterior, applications. Epoxy-based terrazzo will lose its color and slightly peel when used outdoors, whereas cement-based terrazzo will not. In addition to marble aggregate blends, other aggregates have been used, such as
mother of pearl Nacre ( , ), also known as mother of pearl, is an organicinorganic composite material produced by some molluscs as an inner shell layer; it is also the material of which pearls are composed. It is strong, resilient, and iridescent. Nacre is f ...
and abalone shell. Recycled aggregates include: glass, porcelain, concrete, and metal. Shapes and medallions can be fabricated on site by bending divider strips, or off site by water-jet cutting. When the terrazzo is thoroughly cured, helpers grind it with a terrazzo grinder, which is somewhat like a
floor polisher A floor scrubber is a floor cleaning device. It can be a simple tool such as a floor mop or floor brush, or in the form of a walk-behind or a ride-on machine to clean larger areas by injecting water with cleaning solution, scrubbing, and lifting ...
, only much heavier. Slight depressions left by the grinding are filled with a matching grout material and hand-troweled for a smooth, uniform surface; it is then cleaned, polished, and sealed.


Types and systems

Terrazzo installation includes both bonded and unbonded methods. Bonded systems include: bonded underbed, monolithic, chemically bonded, and the most recent, thin set method (
epoxy Epoxy is the family of basic components or cured end products of epoxy resins. Epoxy resins, also known as polyepoxides, are a class of reactive prepolymers and polymers which contain epoxide groups. The epoxide functional group is also coll ...
resin). Bonded terrazzo is applied over a sand-cement mortar underbed which sits on top of a concrete slab. The sand-cement layer allows for variations in the finished concrete slab that it sits on. Monolithic terrazzo is applied directly over an extremely flat and high quality concrete sub-floor. Thin-set terrazzo does not require a concrete sub-floor. Instead, a flexible membrane can be installed so that cracks do not appear on the surface. Unbonded includes the sand cushion method which uses wire reinforcing, an isolation sheet, and sand dusting that absorbs any movement from the concrete slab.


Relation to mosaics

Although terrazzo derives from the mosaic artform, it does not place individual pieces in a decorative pattern. Instead, small pieces are thrown into the mortar base creating a more uniform surface appearance. Decorative patterns are created by using dividers which creates lines between different colored terrazzo mixtures.


Deterioration

Cracking is the most common form of failure and is typically caused by the structural system that supports the terrazzo topping rather than the material itself. Contact with alkalis or acids can deteriorate the bonding agents used in terrazzo. As the aggregates are often marble dust which is calcium carbonate, strong acid can also cause deterioration to the aggregates. When partial replacement is necessary, a "bracketing" system mixing and matching different chips is used to create potential matches. Aged terrazzo can be resurfaced to restore its original look by re-polishing.


See also

* Engineered stone *
Mosaic A mosaic is a pattern or image made of small regular or irregular pieces of colored stone, glass or ceramic, held in place by plaster/mortar, and covering a surface. Mosaics are often used as floor and wall decoration, and were particularly pop ...
*
Polished concrete Polished concrete is a multi-step process where a concrete floor is mechanically ground, honed and polished with bonded abrasives in order to cut a concrete floor's surface. It is then refined with each cut in order to achieve a specified level o ...
*
Portuguese pavement Portuguese may refer to: * anything of, from, or related to the country and nation of Portugal ** Portuguese cuisine, traditional foods ** Portuguese language, a Romance language *** Portuguese dialects, variants of the Portuguese language ** Portu ...


References


External links

* {{Authority control Decorative arts Floors Pre-Pottery Neolithic