1.
Freemasonry
–
The degrees of freemasonry retain the three grades of medieval craft guilds, those of Apprentice, Journeyman or fellow, and Master Mason. These are the degrees offered by Craft Freemasonry, members of these organisations are known as Freemasons or Masons. There are additional degrees, which vary with locality and jurisdiction, the basic, local organisational unit of Freemasonry is the Lodge. The Lodges are usually supervised and governed at the level by a Grand Lodge or Grand Orient. There is no international, worldwide Grand Lodge that supervises all of Freemasonry, each Grand Lodge is independent, modern Freemasonry broadly consists of two main recognition groups. Continental Freemasonry is now the term for the liberal jurisdictions who have removed some, or all. The Masonic Lodge is the organisational unit of Freemasonry. The Lodge meets regularly to conduct the formal business of any small organisation. In addition to business, the meeting may perform a ceremony to confer a Masonic degree or receive a lecture, at the conclusion of the meeting, the Lodge might adjourn for a formal dinner, or festive board, sometimes involving toasting and song. The bulk of Masonic ritual consists of degree ceremonies, candidates for Freemasonry are progressively initiated into Freemasonry, first in the degree of Entered Apprentice. Some time later, in a ceremony, they will be passed to the degree of Fellowcraft. In all of ceremonies, the candidate is entrusted with passwords, signs. Another ceremony is the installation of the Master and officers of the Lodge. In some jurisdictions Installed Master is valued as a separate rank, in other jurisdictions, the grade is not recognised, and no inner ceremony conveys new secrets during the installation of a new Master of the Lodge. Most Lodges have some sort of calendar, allowing Masons. Often coupled with events is the obligation placed on every Mason to contribute to charity. This occurs at both Lodge and Grand Lodge level, Masonic charities contribute to many fields from education to disaster relief. These private local Lodges form the backbone of Freemasonry, and a Freemason will necessarily have been initiated into one of these, there also exist specialist Lodges where Masons meet to celebrate anything from sport to Masonic research
2.
Mortar (masonry)
–
In its broadest sense mortar includes pitch, asphalt, and soft mud or clay, such as used between mud bricks. Mortar comes from Latin mortarium meaning crushed, mortars are typically made from a mixture of sand, a binder, and water. The most common binder since the early 20th century is Portland cement, there are several types of cement mortars and additives. The first mortars were made of mud and clay, because of a lack of stone and an abundance of clay, Babylonian constructions were of baked brick, using lime or pitch for mortar. According to Roman Ghirshman, the first evidence of using a form of mortar was at the Mehrgarh of Baluchistan in Pakistan. The ancient sites of Harappan civilization of third millennium BCE are built with kiln-fired bricks, gypsum mortar, also called plaster of Paris, was used in the construction of the Egyptian pyramids and many other ancient structures. It is made from gypsum, which requires a firing temperature. It is therefore easier to make lime mortar and sets up much faster which may be a reason it was used as the typical mortar in ancient, brick arch. Gypsum mortar is not as durable as other mortars in damp conditions, in early Egyptian pyramids, which were constructed during the Old Kingdom, the limestone blocks were bound by mortar of mud and clay, or clay and sand. In later Egyptian pyramids, the mortar was made of gypsum or lime. Gypsum mortar was essentially a mixture of plaster and sand and was quite soft, in the Indian subcontinent, multiple cement types have been observed in the sites of the Indus Valley Civilization, such as the Mohenjo-daro city-settlement that dates to earlier than 2600 BCE. Bitumen mortar was used at a lower-frequency, including in the Great Bath at Mohenjo-daro. Historically, building with concrete and mortar next appeared in Greece, the excavation of the underground aqueduct of Megara revealed that a reservoir was coated with a pozzolanic mortar 12 mm thick. This aqueduct dates back to c.500 BCE, pozzolanic mortar is a lime based mortar, but is made with an additive of volcanic ash that allows it to be hardened underwater, thus it is known as hydraulic cement. The Greeks obtained the volcanic ash from the Greek islands Thira and Nisiros, or from the then Greek colony of Dicaearchia near Naples, the Romans later improved the use and methods of making what became known as pozzolanic mortar and cement. Even later, the Romans used a mortar without pozzolana using crushed terra cotta, introducing aluminum oxide and this mortar was not as strong as pozzolanic mortar, but, because it was denser, it better resisted penetration by water. Hydraulic mortar was not available in ancient China, possibly due to a lack of volcanic ash, around 500 CE, sticky rice soup was mixed with slaked lime to make an inorganic−organic composite mortar that had more strength and water resistance than lime mortar. It is not understood how the art of making hydraulic mortar and cement, during the Middle Ages when the Gothic cathedrals were being built, the only active ingredient in the mortar was lime
3.
Brick
–
A brick is building material used to make walls, pavements and other elements in masonry construction. Traditionally, the term referred to a unit composed of clay. A brick can be composed of clay-bearing soil, sand, and lime, Bricks are produced in numerous classes, types, materials, and sizes which vary with region and time period, and are produced in bulk quantities. Two basic categories of bricks are fired and non-fired bricks, block is a similar term referring to a rectangular building unit composed of similar materials, but is usually larger than a brick. Lightweight bricks are made from expanded clay aggregate, fired bricks are one of the longest-lasting and strongest building materials, sometimes referred to as artificial stone, and have been used since circa 5000 BC. Air-dried bricks, also known as mudbricks, have an older than fired bricks. Bricks are laid in courses and numerous patterns known as bonds, collectively known as brickwork, the earliest bricks were dried brick, meaning that they were formed from clay-bearing earth or mud and dried until they were strong enough for use. The oldest discovered bricks, originally made from shaped mud and dating before 7500 BC, were found at Tell Aswad, in the upper Tigris region, ceramic, or fired brick was used as early as 3000 BC in early Indus Valley cities. In pre-modern China, bricks were being used from the 2nd millennium BCE at a site near Xian, the carpenters manual Yingzao Fashi, published in 1103 at the time of the Song dynasty described the brick making process and glazing techniques then in use. He also had to know when to quench the kiln with water so as to produce the surface glaze, Early civilisations around the Mediterranean adopted the use of fired bricks, including the Ancient Greeks and Romans. The Roman legions operated mobile kilns, and built large brick structures throughout the Roman Empire, during the Early Middle Ages the use of bricks in construction became popular in Northern Europe, after being introduced there from Northern-Western Italy. An independent style of architecture, known as brick Gothic flourished in places that lacked indigenous sources of rocks. Examples of this style can be found in modern-day Denmark, Germany, Poland. A clear distinction between the two styles developed at the transition to Baroque architecture. In Lübeck, for example, Brick Renaissance is clearly recognisable in buildings equipped with terracotta reliefs by the artist Statius von Düren, production of bricks increased massively with the onset of the Industrial Revolution and the rise in factory building in England. For reasons of speed and economy, bricks were increasingly preferred as building material to stone and it was at this time in London, that bright red brick was chosen for construction to make the buildings more visible in the heavy fog and to help prevent traffic accidents. The transition from the method of production known as hand-moulding to a mechanised form of mass-production slowly took place during the first half of the nineteenth century. His mechanical apparatus soon achieved widespread attention after it was adopted for use by the South Eastern Railway Company for brick-making at their factory near Folkestone, the Bradley & Craven Ltd ‘Stiff-Plastic Brickmaking Machine’ was patented in 1853, apparently predating Clayton
4.
Rock (geology)
–
Rock or stone is a natural substance, a solid aggregate of one or more minerals or mineraloids. For example, granite, a rock, is a combination of the minerals quartz, feldspar. The Earths outer solid layer, the lithosphere, is made of rock, rock has been used by mankind throughout history. The minerals and metals found in rocks have been essential to human civilization, three major groups of rocks are defined, igneous, sedimentary, and metamorphic. The scientific study of rocks is called petrology, which is a component of geology. At a granular level, rocks are composed of grains of minerals, the aggregate minerals forming the rock are held together by chemical bonds. The types and abundance of minerals in a rock are determined by the manner in which the rock was formed, many rocks contain silica, a compound of silicon and oxygen that forms 74. 3% of the Earths crust. This material forms crystals with other compounds in the rock, the proportion of silica in rocks and minerals is a major factor in determining their name and properties. Rocks are geologically classified according to such as mineral and chemical composition, permeability, the texture of the constituent particles. These physical properties are the end result of the processes that formed the rocks, over the course of time, rocks can transform from one type into another, as described by the geological model called the rock cycle. These events produce three general classes of rock, igneous, sedimentary, and metamorphic, the three classes of rocks are subdivided into many groups. However, there are no hard and fast boundaries between allied rocks, hence the definitions adopted in establishing rock nomenclature merely correspond to more or less arbitrary selected points in a continuously graduated series. Igneous rock forms through the cooling and solidification of magma or lava and this magma can be derived from partial melts of pre-existing rocks in either a planets mantle or crust. Typically, the melting of rocks is caused by one or more of three processes, an increase in temperature, a decrease in pressure, or a change in composition, igneous rocks are divided into two main categories, plutonic rock and volcanic. Plutonic or intrusive rocks result when magma cools and crystallizes slowly within the Earths crust, a common example of this type is granite. Volcanic or extrusive rocks result from magma reaching the surface either as lava or fragmental ejecta, the chemical abundance and the rate of cooling of magma typically forms a sequence known as Bowens reaction series. Most major igneous rocks are found along this scale, about 64. 7% of the Earths crust by volume consists of igneous rocks, making it the most plentiful category. Of these, 66% are basalts and gabbros, 16% are granite, only 0. 6% are syenites and 0. 3% peridotites and dunites
5.
Marble
–
Marble is a metamorphic rock composed of recrystallized carbonate minerals, most commonly calcite or dolomite. Geologists use the marble to refer to metamorphosed limestone, however. Marble is commonly used for sculpture and as a building material and this stem is also the basis for the English word marmoreal, meaning marble-like. In Hungarian it is called márvány, Marble is a rock resulting from metamorphism of sedimentary carbonate rocks, most commonly limestone or dolomite rock. Metamorphism causes variable recrystallization of the carbonate mineral grains. The resulting marble rock is composed of an interlocking mosaic of carbonate crystals. Primary sedimentary textures and structures of the carbonate rock have typically been modified or destroyed. Pure white marble is the result of metamorphism of a very pure limestone or dolomite protolith, green coloration is often due to serpentine resulting from originally magnesium-rich limestone or dolostone with silica impurities. These various impurities have been mobilized and recrystallized by the intense pressure, examples of historically notable marble varieties and locations, White marble has been prized for its use in sculptures since classical times. This preference has to do with its softness, which made it easier to carve, relative isotropy and homogeneity, construction marble is a stone which is composed of calcite, dolomite or serpentine which is capable of taking a polish. More generally in construction, specifically the dimension stone trade, the marble is used for any crystalline calcitic rock useful as building stone. For example, Tennessee marble is really a dense granular fossiliferous gray to pink to maroon Ordovician limestone that geologists call the Holston Formation. Ashgabat, the city of Turkmenistan, was recorded in the 2013 Guinness Book of Records as having the worlds highest concentration of white marble buildings. According to the United States Geological Survey, U. S. domestic marble production in 2006 was 46,400 tons valued at about $18.1 million, compared to 72,300 tons valued at $18.9 million in 2005. Crushed marble production in 2006 was 11.8 million tons valued at $116 million, of which 6.5 million tons was finely ground calcium carbonate and the rest was construction aggregate. For comparison,2005 crushed marble production was 7.76 million tons valued at $58.7 million, of which 4.8 million tons was finely ground calcium carbonate, U. S. dimension marble demand is about 1.3 million tons. The DSAN World Demand for Marble Index has shown a growth of 12% annually for the 2000–2006 period, the largest dimension marble application is tile. In 1998, marble production was dominated by 4 countries that accounted for almost half of production of marble
6.
Granite
–
Granite is a common type of felsic intrusive igneous rock that is granular and phaneritic in texture. Granites can be white, pink, or gray in color. The word granite comes from the Latin granum, a grain, in reference to the structure of such a holocrystalline rock. By definition, granite is a rock with at least 20% quartz. The term granitic means granite-like and is applied to granite and a group of igneous rocks with similar textures and slight variations in composition. Occasionally some individual crystals are larger than the groundmass, in case the texture is known as porphyritic. A granitic rock with a texture is known as a granite porphyry. Granitoid is a general, descriptive field term for lighter-colored, coarse-grained igneous rocks, petrographic examination is required for identification of specific types of granitoids. The extrusive igneous rock equivalent of granite is rhyolite, Granite is nearly always massive, hard and tough, and therefore it has gained widespread use throughout human history, and more recently as a construction stone. The average density of granite is between 2.65 and 2.75 g/cm3, its compressive strength usually lies above 200 MPa, and its viscosity near STP is 3–6 •1019 Pa·s. The melting temperature of dry granite at ambient pressure is 1215–1260 °C, it is reduced in the presence of water. Granite has poor primary permeability, but strong secondary permeability, true granite according to modern petrologic convention contains both plagioclase and alkali feldspars. When a granitoid is devoid or nearly devoid of plagioclase, the rock is referred to as alkali feldspar granite, when a granitoid contains less than 10% orthoclase, it is called tonalite, pyroxene and amphibole are common in tonalite. A granite containing both muscovite and biotite micas is called a binary or two-mica granite, two-mica granites are typically high in potassium and low in plagioclase, and are usually S-type granites or A-type granites. A worldwide average of the composition of granite, by weight percent, based on 2485 analyses. Much of it was intruded during the Precambrian age, it is the most abundant basement rock that underlies the relatively thin veneer of the continents. Outcrops of granite tend to form tors and rounded massifs, granites sometimes occur in circular depressions surrounded by a range of hills, formed by the metamorphic aureole or hornfels. Granite often occurs as small, less than 100 km² stock masses
7.
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, cream-colored and it is formed by a process of rapid precipitation of calcium carbonate, often at the mouth of a hot spring or in a limestone cave. In the latter, it can form stalactites, stalagmites, and it is frequently used in Italy and elsewhere as a building material. Travertine is a sedimentary rock, formed by the precipitation of carbonate minerals from solution in ground and surface waters. Similar deposits formed from water are known as tufa. The word travertine is derived from the Italian travertino, itself a derivation of the Latin tiburtinus ‘of Tibur’ and its namesake is also the origin of Tivoli, a district near Rome. Modern travertine is formed from geothermally heated supersaturated alkaline waters, with raised pCO2, on emergence, waters degas CO2 due to the lower atmospheric pCO2, resulting in an increase in pH. Since carbonate solubility decreases with increased pH, precipitation is induced, precipitation may be enhanced by factors leading to a reduction in pCO2, for example increased air-water interactions at waterfalls may be important, as may photosynthesis. Precipitation may also be enhanced by evaporation in some springs, both calcite and aragonite are found in hot spring travertines, aragonite is preferentially precipitated when temperatures are hot, while calcite dominates when temperatures are cooler. When pure and fine, travertine is white, but often it is brown to yellow due to impurities, travertine may precipitate out directly onto rock and other inert materials as in Pamukkale or Yellowstone for example. The latter has a historic value, because it was one of the quarries that Gian Lorenzo Bernini selected material from to build the famous Colonnade of St. Peters Square in Rome in 1656-1667. Michaelangelo also chose travertine as the material for the ribs of the dome of St Peters Basilica. Travertine derives its name from the town, known as Tibur in ancient Roman times. The ancient name for the stone was lapis tiburtinus, meaning tibur stone, detailed studies of the Tivoli and Guidonia travertine deposits revealed diurnal and annual rhythmic banding and laminae, which have potential use in geochronology. Cascades of natural lakes formed behind travertine dams can be seen in Pamukkale, Turkey, in Central Europes last post-glacial palaeoclimatic optimum, huge deposits of tufa formed from karst springs. On a smaller scale, these karst processes are still working, travertine has been an important building material since the Middle Ages. Travertine has formed sixteen huge, natural dams in a valley in Croatia known as Plitvice Lakes National Park, clinging to moss and rocks in the water, the travertine has built up over several millennia to form waterfalls up to 70 m in height. In the U. S. the most well-known place for travertine formation is Yellowstone National Park, Oklahoma has two parks dedicated to this natural wonder
8.
Limestone
–
Limestone is a sedimentary rock, composed mainly of skeletal fragments of marine organisms such as coral, forams and molluscs. Its major materials are the minerals calcite and aragonite, which are different crystal forms of calcium carbonate, about 10% of sedimentary rocks are limestones. The solubility of limestone in water and weak acid solutions leads to karst landscapes, most cave systems are through limestone bedrock. The first geologist to distinguish limestone from dolomite was Belsazar Hacquet in 1778, like most other sedimentary rocks, most limestone is composed of grains. Most grains in limestone are skeletal fragments of organisms such as coral or foraminifera. Other carbonate grains comprising limestones are ooids, peloids, intraclasts and these organisms secrete shells made of aragonite or calcite, and leave these shells behind when they die. Limestone often contains variable amounts of silica in the form of chert or siliceous skeletal fragment, some limestones do not consist of grains at all, and are formed completely by the chemical precipitation of calcite or aragonite, i. e. travertine. Secondary calcite may be deposited by supersaturated meteoric waters and this produces speleothems, such as stalagmites and stalactites. Another form taken by calcite is oolitic limestone, which can be recognized by its granular appearance, the primary source of the calcite in limestone is most commonly marine organisms. Some of these organisms can construct mounds of rock known as reefs, below about 3,000 meters, water pressure and temperature conditions cause the dissolution of calcite to increase nonlinearly, so limestone typically does not form in deeper waters. Limestones may also form in lacustrine and evaporite depositional environments, calcite can be dissolved or precipitated by groundwater, depending on several factors, including the water temperature, pH, and dissolved ion concentrations. Calcite exhibits a characteristic called retrograde solubility, in which it becomes less soluble in water as the temperature increases. Impurities will cause limestones to exhibit different colors, especially with weathered surfaces, Limestone may be crystalline, clastic, granular, or massive, depending on the method of formation. Crystals of calcite, quartz, dolomite or barite may line small cavities in the rock, when conditions are right for precipitation, calcite forms mineral coatings that cement the existing rock grains together, or it can fill fractures. Travertine is a banded, compact variety of limestone formed along streams, particularly there are waterfalls. Calcium carbonate is deposited where evaporation of the leaves a solution supersaturated with the chemical constituents of calcite. Tufa, a porous or cellular variety of travertine, is found near waterfalls, coquina is a poorly consolidated limestone composed of pieces of coral or shells. During regional metamorphism that occurs during the building process, limestone recrystallizes into marble
9.
Glass
–
Glass is a non-crystalline amorphous solid that is often transparent and has widespread practical, technological, and decorative usage in, for example, window panes, tableware, and optoelectronics. The most familiar, and historically the oldest, types of glass are silicate glasses based on the chemical compound silica, the primary constituent of sand. The term glass, in usage, is often used to refer only to this type of material. Many applications of silicate glasses derive from their optical transparency, giving rise to their use as window panes. Glass can be coloured by adding metallic salts, and can also be painted and printed with vitreous enamels and these qualities have led to the extensive use of glass in the manufacture of art objects and in particular, stained glass windows. Although brittle, silicate glass is extremely durable, and many examples of glass fragments exist from early glass-making cultures, because glass can be formed or moulded into any shape, it has been traditionally used for vessels, bowls, vases, bottles, jars and drinking glasses. In its most solid forms it has also used for paperweights, marbles. Some objects historically were so commonly made of glass that they are simply called by the name of the material, such as drinking glasses. Porcelains and many polymer thermoplastics familiar from everyday use are glasses and these sorts of glasses can be made of quite different kinds of materials than silica, metallic alloys, ionic melts, aqueous solutions, molecular liquids, and polymers. For many applications, like glass bottles or eyewear, polymer glasses are a lighter alternative than traditional glass, silica is a common fundamental constituent of glass. In nature, vitrification of quartz occurs when lightning strikes sand, forming hollow, fused quartz is a glass made from chemically-pure SiO2. It has excellent resistance to shock, being able to survive immersion in water while red hot. However, its high melting-temperature and viscosity make it difficult to work with, normally, other substances are added to simplify processing. One is sodium carbonate, which lowers the transition temperature. The soda makes the glass water-soluble, which is undesirable, so lime, some magnesium oxide. The resulting glass contains about 70 to 74% silica by weight and is called a soda-lime glass, soda-lime glasses account for about 90% of manufactured glass. Most common glass contains other ingredients to change its properties, lead glass or flint glass is more brilliant because the increased refractive index causes noticeably more specular reflection and increased optical dispersion. Adding barium also increases the refractive index, iron can be incorporated into glass to absorb infrared energy, for example in heat absorbing filters for movie projectors, while cerium oxide can be used for glass that absorbs UV wavelengths
10.
Adobe
–
Adobe is a building material made from earth and often organic material. Adobe is among the earliest building materials, and is used throughout the world, modern methods of construction allow the pouring of whole adobe walls that are reinforced with steel. In dry climates, adobe structures are extremely durable, and account for some of the oldest existing buildings in the world. Adobe buildings offer significant advantages due to their greater thermal mass, cases where adobe structures were widely damaged during earthquakes include the 1976 Guatemala earthquake, the 2003 Bam earthquake and the 2010 Chile earthquake. Puebloan peoples built their structures with handfuls or basketfuls of adobe. Adobe bricks were used in Spain from the Late Bronze and Iron Ages and its wide use can be attributed to its simplicity of design and manufacture, and economics. A distinction is made between the smaller adobes, which are about the size of ordinary baked bricks, and the larger adobines. The word adobe /əˈdoʊbiː/ has existed for around 4000 years with little change in either pronunciation or meaning. The word can be traced from the Middle Egyptian word ɟbt mudbrick, Middle Egyptian evolved into Late Egyptian, Demotic or pre-Coptic, and finally to Coptic, where it appeared as τωωβε tōʾpə. This was borrowed into Arabic as الطوب aṭ-ṭawbu or aṭ-ṭūbu, with the definite article al- attached, tuba, English borrowed the word from Spanish in the early 18th century. In more modern English usage, the adobe has come to include a style of architecture popular in the desert climates of North America. An adobe brick is a material made of earth mixed with water. The soil composition typically contains sand, silt and clay, straw is useful in binding the brick together and allowing the brick to dry evenly, thereby preventing cracking due to uneven shrinkage rates through the brick. The most desirable soil texture for producing the mud of adobe is 15% clay, 10–30% silt, another source quotes 15–25% clay and the remainder sand and coarser particles up to cobbles 50 to 250 mm with no deleterious effect. Modern adobe is stabilized with either emulsified asphalt or Portland cement up to 10% by weight, no more than half the clay content should be expansive clays with the remainder non-expansive illite or kaolinite. Too much expansive clay results in uneven drying through the resulting in cracking. Typically the soils of the Southwest United States, where construction is in use, are an adequate composition. Adobe walls are bearing, i. e. they carry their own weight into the foundation rather than by another structure
11.
Construction worker
–
A construction worker is a tradesperson, labourer, or professional employed in the physical construction of the built environment and its infrastructure. The term construction worker is a term and most construction workers are primarily described by the type of work they perform. Construction workers may also colloquially be referred to as hard hat workers or hard hats, construction workers often work under a construction foreman. The division of labor of construction encompasses a range of skilled. Construction safety is important to ensure a safe environment for the workers. All construction workers need to be educated on safety at each site to minimize injury. In 2008, a Human Rights Watch report described unsafe and unfair working conditions, the International Labour Organization estimated that, at the end of 2006, 90% of the 40 million construction workers in China were migrant workers. Many of the migrant workers turned to work after their farming communities collapsed into poverty. In the United States, illegal immigrant labor is prevalent in the construction industry.20 a day
12.
Rebar
–
Rebars surface is often patterned to form a better bond with the concrete. Rebar has been used in construction since at least the 15th century, more recently, during the 18th century, rebar was used to form the carcass of the Leaning Tower of Nevyansk in Russia, built on the orders of the industrialist Akinfiy Demidov. The cast iron used for the rebar was of high quality, the carcass of the tower was connected to its cast iron tented roof, crowned with one of the first known lightning rods. More recently these techniques have been refined by embedding the steel bars in the concrete, concrete is a material that is very strong in compression, but relatively weak in tension. To compensate for this imbalance in concretes behavior, rebar is cast into it to carry the tensile loads, rebar is also employed to confer resistance to concentrated loads by providing enough localized resistance and stiffness for a load to spread through a wider area. Rebar may also be used to other steel bars in the correct position to accommodate their loads. External steel tie bars can constrain and reinforce masonry structures, as illustrated by the Nevyansk Tower or ancient structures in Rome, masonry structures and the mortar holding them together have similar properties to concrete and also have a limited ability to carry tensile loads. Some standard masonry units like blocks and bricks are made with voids to accommodate rebar and this combination is known as reinforced masonry. Steel has a thermal expansion coefficient nearly equal to that of modern concrete, if this were not so, it would cause problems through additional longitudinal and perpendicular stresses at temperatures different from the temperature of the setting. To prevent such a failure, rebar is either deeply embedded into adjacent structural members, or bent and hooked at the ends to lock it around the concrete and other rebar. This first approach increases the friction locking the bar into place, common rebar is made of unfinished tempered steel, making it susceptible to rusting. Normally the concrete cover is able to provide a pH value higher than 12 avoiding the corrosion reaction, too little concrete cover can compromise this guard through carbonation from the surface, and salt penetration. Too much concrete cover can cause bigger crack widths which also compromises the local guard and this phenomenon is known as oxide jacking. This is a problem where the concrete is exposed to salt water, as in bridges where salt is applied to roadways in winter. Even damaged bars have shown better performance than uncoated reinforcing bars, though issues from debonding of the coating from the bars. These bars are used in over 70,000 bridge decks in the USA, fiber-reinforced polymer rebar is also used in high-corrosion environments. It is available in forms, such as spirals for reinforcing columns, common rods. Most commercially available rebar is made from glass fibre reinforced thermoset resins
