Terrazzo

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A uniform terrazzo floor in a German church Rettenbach 8.jpg
A uniform terrazzo floor in a German church
One of the most well known examples of terrazzo flooring is the Hollywood Walk of Fame. Hollywood Walk of Fame (7960322318).jpg
One of the most well known examples of terrazzo flooring is the Hollywood Walk of Fame.

Terrazzo is a composite material, poured in place or precast, which is used for floor and wall treatments. It consists of chips of marble, quartz, granite, glass, or other suitable material, poured with a cementitious binder (for chemical binding), polymeric (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. [1]

Contents

History

Terrazzo proper

Although the history of terrazzo can be traced back to the ancient mosaics 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. [2] Until then it was hand polished with a long handled tool called a galera. [2] 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. [3] 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 and Moderne styles from the 1920s to 1940s favored terrazzo with the dividers allowing for straight or curved lines that increased the decorative potential. [4] 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. [5] One of the most well 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. [6]

Archaeological use of the term

Archaeologists have adopted the term terrazzo to describe the floors of early Neolithic buildings (PPNA and PPNB, ca. 9,000–8,000 BC) in Western Asia constructed of burnt lime 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 of implements, predates production of fired pottery by almost a thousand years.[ citation needed ] In the early Neolithic settlement of Çayönü in eastern Turkey about 90 m2 (970 sq ft) of terrazzo floors have been uncovered. The floors of the PPN B settlement of Nevalı Çori measure about 80 m2 (860 sq ft). They are 15 cm (5.9 in) 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. [7] [ clarification needed ] Recent experiments by Affonso and Pernicka [8] 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, Jericho, and Kastros (Cyprus).

Production

Terrazzo with stylized Native-American design at the Hoover Dam Pima1.jpg
Terrazzo with stylized Native-American design at the Hoover Dam
Terrazzo wall at the Gamla stan metro station, Stockholm Gamla stan tunnelbana terrazzo 070330.JPG
Terrazzo wall at the Gamla stan metro station, Stockholm

Terrazzo artisans create walls, floors, patios, and panels by exposing marble chips and other fine aggregates on the surface of finished concrete or epoxy-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 3 to 4 inches (76 to 102 mm) deep. After the forms are removed from the foundation, workers add a 1 inch (25 mm) 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 (100–125 pounds (45–57 kg)) over the entire surface.

In the 1970s, polymer-based terrazzo was introduced and is called thin-set terrazzo. Initially polyester and vinyl ester 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, 14 to 38 inch (6.4 to 9.5 mm) 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 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, 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. [9]

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 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. [10] Unbonded includes the sand cushion method which uses wire reinforcing, an isolation sheet, and sand dusting that absorbs any movement from the concrete slab. [11]

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. [11] Aged terrazzo can be resurfaced to restore its original look by re-polishing. [12]

See also

Related Research Articles

Concrete Composite construction material

Concrete is a composite material composed of fine and coarse aggregate bonded together with a fluid cement that hardens (cures) over time. Concrete is the second-most-used substance in the world after water, and is the most widely used building material. Its usage worldwide, ton for ton, is twice that of steel, wood, plastics, and aluminum combined. Globally, the ready-mix concrete industry, the largest segment of the concrete market, is projected to exceed $600 billion in revenue by 2025. This widespread use results in a number of environmental impacts. Most notably, the production process for cement produces large volumes of greenhouse gas emissions, leading to net 8% of global emissions. Other environmental concerns include widespread illegal sand mining, impacts on the surrounding environment such as increased surface runoff or urban heat island effect, and potential public health implications from toxic ingredients. Significant research and development is being done to try to reduce the emissions or make concrete a source of carbon sequestration, and increase recycled and secondary raw materials content into the mix to achieve a circular economy. Concrete is expected to be a key material for structures resilient to climate disasters, as well as a solution to mitigate the pollution of other industries, capturing wastes such as coal fly ash or bauxite tailings and residue.

Flooring is the general term for a permanent covering of a floor, or for the work of installing such a floor covering. Floor covering is a term to generically describe any finish material applied over a floor structure to provide a walking surface. Both terms are used interchangeably but floor covering refers more to loose-laid materials.

Road surface Road covered with durable surface material

A road surface, or pavement, is the durable surface material laid down on an area intended to sustain vehicular or foot traffic, such as a road or walkway. In the past, gravel road surfaces, cobblestone and granite setts were extensively used, but these have mostly been replaced by asphalt or concrete laid on a compacted base course. Asphalt mixtures have been used in pavement construction since the beginning of the 20th century and are of two types: metalled roads and unmetalled roads. Metalled roadways are made to sustain vehicular load and so are usually made on frequently used roads. Unmetalled roads, also known as gravel roads, are rough and can sustain less weight. Road surfaces are frequently marked to guide traffic.

Grinding wheel

A grinding wheel is a wheel used for grinding. Grinding wheels are composed of abrasive compounds and are used for various grinding and abrasive machining operations. Such wheels are used in grinding machines.

Dowel bar retrofit

A dowel bar retrofit (DBR) is a method of reinforcing cracks in highway pavement by inserting steel dowel bars in slots cut across the cracks. It is a technique which several U.S. states' departments of transportation have successfully used in repairs to address faulting in older jointed plain concrete pavements. The typical approach is to saw cut and jackhammer out the slots for the dowels. Following dowel placement the slots are then typically backfilled with a non-shrink concrete mixture, and the pavement is diamond-ground to restore smoothness.

Countertop

A countertop, also counter top, counter, benchtop, worktop or kitchen bench, is the firm, flat, horizontal surface of a counter. They are built for work in kitchens or other food preparation areas, bathrooms or lavatories, and workrooms in general. The surface is frequently installed upon and supported by cabinets, positioned at an ergonomic height for the user and the particular task for which it is designed. A countertop may be constructed of various materials with different attributes of functionality, durability and aesthetics, and may have built-in appliances, or accessory items relative to the intended application.

Engineered stone

Engineered stone is a composite material made of crushed stone bound together by an adhesive,. This category includes engineered quartz, polymer concrete and engineered marble stone. The application of these products depends on the original stone used. For engineered marbles the most common application is indoor flooring and walls, while the quartz based product is used primarily for kitchen countertops as an alternative to laminate or granite. Related materials include geopolymers and cast stone. Unlike terrazzo, the material is factory made in either blocks or slabs, cut and polished by fabricators, and assembled at the worksite.

Metakaolin is the anhydrous calcined form of the clay mineral kaolinite. Minerals that are rich in kaolinite are known as china clay or kaolin, traditionally used in the manufacture of porcelain. The particle size of metakaolin is smaller than cement particles, but not as fine as silica fume.

Diamond tool

A diamond tool is a cutting tool with diamond grains fixed on the functional parts of the tool via a bonding material or another method. As diamond is a superhard material, diamond tools have many advantages as compared with tools made with common abrasives such as corundum and silicon carbide.

Decorative concrete

Decorative concrete is the use of concrete as not simply a utilitarian medium for construction but as an aesthetic enhancement to a structure, while still serving its function as an integral part of the building itself such as floors, walls, driveways, and patios.

Polymer concrete is a type of concrete that uses polymer to replace lime-type cements as a binder. In some cases the polymer is used in addition to portland cement to form Polymer Cement Concrete (PCC) or Polymer Modified Concrete (PMC). Polymers in concrete have been overseen by Committee 548 of the American Concrete Institute since 1971.

Granolithic

Granolithic screed, also known as granolithic paving and granolithic concrete, is a type of construction material composed of cement and fine aggregate such as granite or other hard-wearing rock. It is generally used as flooring, or as paving. It has a similar appearance to concrete, and is used to provide a durable surface where texture and appearance are usually not important. It is commonly laid as a screed. Screeds are a type of flooring laid on top of the structural element to provide a level surface on which the "wearing flooring" is laid. A screed can also be laid bare, as it provides a long-lasting surface.

Cement render

Cement rendering is the application of a premixed layer of sand and cement to brick, concrete, stone, or mud brick. It is often textured, colored, or painted after application. It is generally used on exterior walls but can be used to feature an interior wall.

Polished concrete Concrete which has been mechanically ground, honed, and polished

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 of appearance.

Concrete sealers are applied to concrete to protect it from surface damage, corrosion, and staining. They either block the pores in the concrete to reduce absorption of water and salts or form an impermeable layer which prevents such materials from passing.

Types of concrete concrete technology used in building construction

Concrete is produced in a variety of compositions, finishes and performance characteristics to meet a wide range of needs.

Concrete degradation Concrete corrosion

Concrete degradation may have various causes. Concrete can be damaged by fire, aggregate expansion, sea water effects, bacterial corrosion, calcium leaching, physical damage and chemical damage. This process adversely affects concrete exposed to these damaging stimuli.

Concrete has relatively high compressive strength, but significantly lower tensile strength. The compressive strength is typically controlled with the ratio of water to cement when forming the concrete, and tensile strength is increased by additives, typically steel, to create reinforced concrete. In other words we can say concrete is made up of sand ,ballast, cement and water.

Diamond grinding cup wheel

A diamond grinding cup wheel is a metal-bonded diamond tool with diamond segments welded or cold-pressed on a steel wheel body, which usually looks like a cup. Diamond grinding cup wheels are usually mounted on concrete grinders to grind abrasive building materials like concrete, granite and marble.

Flexible stone veneer

Flexible stone veneer is a veneer with a layer of stone 1 to 5 mm thick. Flexible stone veneers should not be confused with traditional stone veneer. It is used for both interior and exterior and especially where bending to a curved surface is required. Flexible stone veneers are made from various types of slate, schist, or marble.

References

  1. Brooke, Eliza (15 October 2019). "Terrazzo used to be kitschy. Now it's on everything from Spalding basketballs to Madewell dresses". Vox . Retrieved 15 October 2019.
  2. 1 2 Johnson, Walter (1995). Twentieth Century Materials: History and Conservation. New York: McGraw Hill. p. 203.
  3. Del Turco, L., and Bros., Inc. (1924). Modern Mosaic and Terrazzo Floors; a Handbook on the Improvement of Laying Terrazzo Floors with Metal Dividers. Harrison, NJ: Del Turco, L., and Bros., Inc. pp. 6–7.
  4. Jester, Thomas (1995). Twentieth Century Materials: History and Conservation. New York: McGraw Hill. p. 204.
  5. Jester, Thomas (1995). Twentieth Century Materials: History and Conservation. New York: McGraw Hill. p. 205.
  6. "Hollywood Chamber of Commerce".
  7. Gourdin, W. H.; Kingery, W. D. (1975). "The Beginnings of Pyrotechnology: Neolithic and Egyptian Lime Plaster". Journal of Field Archaeology. 2 (1–2): 133–150. doi:10.1179/009346975791491277.
  8. Affonso, Maria Thais Crepaldi; Pernicka, Ernst (2001). "Neolithic Lime Plasters and Pozzolanic Reactions: Are They Occasional Occurrences?". In Boehmer, Rainer Michael; Maran, Joseph (eds.). Lux orientis: Archäologie Zwischen Asien und Europa. Festschrift für Harald Hauptmann zum 65. Geburtstag. Internationale Archäologie: Studia honoraria Volume 12. Rahden/Westfallen, Germany: Verlag Marie Leidorf. pp. 9–13. ISBN   9783896463920. OCLC   646779465 . Retrieved 15 June 2013.
  9. "Cement Masons and Terrazzo Workers". Occupational Outlook Handbook, 2012–13 Edition. Bureau of Labor Statistics, U.S. Department of Labor. 29 March 2012. Retrieved 15 June 2013.
  10. "Flooring - Terrazzo - archtoolbox.com". archtoolbox.com. Retrieved 2017-12-05.
  11. 1 2 Jester, Thomas (1995). Twentieth Century Materials: History and Conservation. New York: McGraw Hill. p. 207.
  12. "Regrinding Terrazzo Floors".