A temple is a structure reserved for religious or spiritual rituals and activities such as prayer and sacrifice. It is used for such buildings belonging to all faiths where a more specific term such as church, mosque or synagogue is not used in English; these include Hinduism and Jainism among religions with many modern followers, as well as other ancient religions such as Ancient Egyptian religion. The form and function of temples is thus variable, though they are considered by believers to be in some sense the "house" of one or more deities. Offerings of some sort are made to the deity, other rituals enacted, a special group of clergy maintain, operate the temple; the degree to which the whole population of believers can access the building varies significantly. Temples have a main building and a larger precinct, which may contain many other buildings, or may be a dome shaped structure, much like an igloo; the word comes from Ancient Rome, where a templum constituted a sacred precinct as defined by a priest, or augur.
It has the same root as the word "template", a plan in preparation of the building, marked out on the ground by the augur. Templa became associated with the dwelling places of a god or gods. Despite the specific set of meanings associated with the word, it has now become used to describe a house of worship for any number of religions and is used for time periods prior to the Romans; the temple-building tradition of Mesopotamia derived from the cults of gods and deities in the Mesopotamian religion. It spanned several civilizations; the most common temple architecture of Mesopotamia is the structure of sun-baked bricks called a Ziggurat, having the form of a terraced step pyramid with a flat upper terrace where the shrine or temple stood. Ancient Egyptian temples were meant as places for the deities to reside on earth. Indeed, the term the Egyptians most used to describe the temple building, ḥwt-nṯr, means "mansion of a god". A god's presence in the temple linked the human and divine realms and allowed humans to interact with the god through ritual.
These rituals, it was believed, sustained the god and allowed it to continue to play its proper role in nature. They were therefore a key part of the maintenance of maat, the ideal order of nature and of human society in Egyptian belief. Maintaining maat was the entire purpose of Egyptian religion, thus it was the purpose of a temple as well. Ancient Egyptian temples were of economic significance to Egyptian society; the temples stored and redistributed grain and came to own large portions of the nation's arable land. In addition, many of these Egyptian temples utilized the Tripartite Floor Plan in order to draw visitors to the center room. Though today we call most Greek religious buildings "temples," the ancient Greeks would have referred to a temenos, or sacred precinct, its sacredness connected with a holy grove, was more important than the building itself, as it contained the open air altar on which the sacrifices were made. The building which housed the cult statue in its naos was a rather simple structure, but by the middle of the 6th century BCE had become elaborate.
Greek temple architecture had a profound influence on ancient architectural traditions. The rituals that located and sited Roman temples were performed by an augur through the observation of the flight of birds or other natural phenomenon. Roman temples faced east or toward the rising sun, but the specifics of the orientation are not known today. In ancient Rome only the native deities of Roman mythology had a templum; the Romans referred to a holy place of a pagan religion as fanum. Medieval Latin writers sometimes used the word templum reserved for temples of the ancient Roman religion. In some cases it is hard to determine whether a temple was an outdoor shrine. For temple buildings of the Vikings, the Old Norse term hof is used. A Zoroastrian temple may be called a Dar-e-mehr and a Atashkadeh. A fire temple in Zoroastrianism is the place of worship for Zoroastrians. Zoroastrians revere fire in any form, their temples contains an eternal flame, with Atash Behram as the highest grade of all, as it combines 16 different types of fire gathered in elaborate rituals.
In the Zoroastrian religion, together with clean water, are agents of ritual purity. Clean, white "ash for the purification ceremonies is regarded as the basis of ritual life," which, "are the rites proper to the tending of a domestic fire, for the temple fire is that of the hearth fire raised to a new solemnity". Hindu temples are known by many different names, varying on region and language, including Alayam, Mandira, Gudi, Koil, Kovil, Déul, Devasthana, Deva Mandiraya and Devalaya. A Hindu temple is the seat and dwelling of Hindu gods, it is a structure designed to bring human gods together according to Hindu faith. Inside its Garbhagriha innermost sanctum, a Hindu temple contains a Hindu god's image. Hindu temples are magnificent with a rich history. There is evidence of use of sacred ground as far back as the Bronze Age and during the Indus Valley Civilization. Outside of the Indian subcontinent (India
A morgue or mortuary is used for the storage of human corpses awaiting identification or removal for autopsy or respectful burial, cremation or other method. In modern times corpses have customarily been refrigerated to delay decomposition. Mortuary early 14c. From Anglo-French mortuarie "gift to a parish priest from a deceased parishioner," from Medieval Latin mortuarium, noun use of neuter of Late Latin adjective mortuarius "pertaining to the dead," from Latin mortuus, pp. of mori "to die". Meaning "place where bodies are kept temporarily" first recorded 1865, a euphemism for earlier English term "deadhouse." Morgue from the French morgue, which means'to look at solemnly, to defy'. First used to describe the inner wicket of a prison, where new prisoners were kept so that jailers and turnkeys could recognize them in the future, it took on its modern meaning in fifteenth-century Paris, being used to describe part of the Châtelet used for the storage and identification of unknown corpses. Morgue is predominantly used in North American English, while mortuary is more common in British English, although both terms are used interchangeably.
The euphemisms “Rose Cottage” and “Rainbow’s End” are sometimes used in British hospitals to enable discussion in front of patients, the latter for children. A person responsible for handling and washing bodies is now known as a diener, morgue attendant, or autopsy technician. There are two types of mortuary cold chambers: Positive temperatureBodies are kept between 2 °C and 4 °C. While this is used for keeping bodies for up to several weeks, it does not prevent decomposition, which continues at a slower rate than at room temperature. Negative temperatureBodies are kept at between −10 °C and −50 °C. Used at forensic institutes when a body has not been identified. At these temperatures the body is frozen and decomposition is much reduced. In some countries, the body of the deceased is embalmed before disposal, which makes refrigeration unnecessary. In many countries, the family of the deceased must make the burial within 72 hours of death, but in some other countries it is usual that burial takes place some weeks or months after the death.
This is why some corpses are kept as long in a funeral home. When the family has enough money to organize the ceremony, the corpse is taken from the cold chamber for burial. In some funeral homes, the morgue is in the same room, or directly adjacent to, the specially designed ovens, known as retorts, that are used in funerary cremation; some religions dictate. To honor these religious rites, many funeral homes install a viewing window, which allows the family to watch as the body is inserted into the retort. In this way, the family can honor their customs without entering the morgue. Oversized mortuary fridge spaces have been installed in British hospitals to cope with the increase in obesity. A waiting mortuary is a mortuary building designed for the purpose of confirming that deceased persons are deceased. Prior to the advent of modern methods of verifying death, people feared that they would be buried alive. To alleviate such fears, the deceased were housed for a time in waiting mortuaries, where attendants would watch for signs of life.
The corpses would be allowed to decompose prior to burial. Waiting mortuaries were most popular in 19th-century Germany, were large, ornate halls. A bell was strung to the corpses to alert attendants of any motion. Although there is no documented case of a person being saved from accidental burial in this way, it is sometimes erroneously believed that this was the origin of the phrase “saved by the bell”, whilst in fact, the phrase originates from the sport of boxing. In American English: Morgue is used to refer to the room in which newspaper or magazine publishers keep their back issues and other historical references, as they serve a similar purpose to human morgues. See Morgue file. Morgue is used in some science fiction books as the name for the armory aboard ships, when they contain some form of powered armor. Mortuary can refer to a funeral home. Body bag Diener Pathology Tissue digestion Toe tag Body farm
A rose window or Catherine window is used as a generic term applied to a circular window, but is used for those found in churches of the Gothic architectural style that are divided into segments by stone mullions and tracery. The name "rose window" was not used before the 17th century and according to the Oxford English Dictionary, among other authorities, comes from the English flower name rose; the term "wheel window" is applied to a window divided by simple spokes radiating from a central boss or opening, while the term "rose window" is reserved for those windows, sometimes of a complex design, which can be seen to bear similarity to a multi-petalled rose. Rose windows are called Catherine windows after Saint Catherine of Alexandria, sentenced to be executed on a spiked wheel. A circular window without tracery such as are found in many Italian churches, is referred to as an ocular window or oculus. Rose windows are characteristic of Gothic architecture and may be seen in all the major Gothic Cathedrals of Northern France.
Their origins are much earlier and rose windows may be seen in various forms throughout the Medieval period. Their popularity was revived, with other medieval features, during the Gothic revival of the 19th century so that they are seen in Christian churches all over the world. Oculi: These could be open or blind, could be filled with thin alabaster. During the late Gothic period large ocular windows were common in Italy, being used in preference to traceried windows and being filled with elaborate pictures in stained glass designed by the most accomplished Late Medieval and Early Renaissance designers including Duccio, Donatello and Ghiberti. Wheel Windows: These windows had a simple tracery of spokes radiating either from a central boss or from a central roundel. Popular during the Romanesque period and Gothic Italy, they are found across Europe but Germany and Italy, they occur in Romanesque Revival buildings of the 19th and 20th centuries. Plate Tracery: Rose windows with pierced openings rather than tracery occur in the transition between Romanesque and Gothic in France and most notably at Chartres.
The most notable example in England is the north transept window, known as the "Dean's Eye" in Lincoln Cathedral. These windows are found in 19th-century Revival buildings. Early Gothic: Rose windows with tracery comprising overlapping arcs like flower petals and square shapes; this form occurs in Northern France, notably at Laon Cathedral and England. This style of window is popular in Gothic Revival architecture for the similarity that it has to a flower and is utilised with specific reference to Our Lady of the Rosary. Rayonnant Gothic: The rose windows are divided by mullions radiating from a central roundel, overlapping in a complex design, each light terminating in a pointed arch and interspersed with quatrefoils and other such shapes. Many of the largest rose windows in France are of this type, notably those at Paris and in the transepts of St Denis. An example in England is that in the north transept of Westminster Abbey; this style occurs in Gothic churches and is widely imitated in Gothic Revival buildings.
Flamboyant Gothic: The style is marked by S-curves in the tracery causing each light to take on a flamelike or "flamboyant" shape. Many windows are composed of regularly shaped lights the richness of design dependent on the multiplicity of parts. Good examples are at Paris; some Late Gothic rose windows are of immense complexity of design using elements of the Gothic style in unexpected ways. A magnificent example is that of the façade of Amiens Cathedral. Although the design radiates from a central point, it may not be symmetrical about each axis; this may be seen in the Flamboyant Decorated Gothic window called the "Bishop’s Eye" at Lincoln Cathedral in which the design takes the form of two ears of wheat. Renaissance: The Renaissance made a break with the Gothic style, a return to the Classical. Plain untraceried oculi were sometimes employed, either in Classical pediments or around domes as at the Pazzi Chapel, Florence. Baroque: The Baroque style saw much greater use of ocular windows, which were not always circular, but oval or of a more complex shape.
They were untraceried or crossed by mullions of simple form but were surrounded by ornate carving. The purpose of such windows was the subtle illumination of interior spaces, without resorting to large windows offering external visibility, they form a dominant visual element to either the façade or the interior as do the great Gothic windows. However, there are some notable exceptions, in particular the glorious burst of light which pours through the oval alabaster window depicting the Holy Spirit in the Reredos behind the High Altar of St. Peter’s Basilica, Rome. Modern: Modern circular windows, which are most of a simple ocular type, have an eclectic range of influences which includes abstract art, ship's portholes and the unglazed circular openings of Oriental architecture; the origin of the rose. These large circular openings let in both light and air, the best known being that at the top of the dome of the Pantheon. Windows with stone tracery make their emergence in Antiquity. Geometrical patterns of roses are developed and common in Roman mosaic.
In Early Christian and Byzantine architecture, there are examples of the use of circular oculi. They occur either around the drum of a dome, as at the Church of the Holy Sepulchre, Jerusalem, or high in the end of a gable of low-pitched Classical pediment form, as at Sant'Agnese fuori le mura and Torcello Cathedral. A window of
In the history of Europe, the Middle Ages lasted from the 5th to the 15th century. It began with the fall of the Western Roman Empire and merged into the Renaissance and the Age of Discovery; the Middle Ages is the middle period of the three traditional divisions of Western history: classical antiquity, the medieval period, the modern period. The medieval period is itself subdivided into the Early and Late Middle Ages. Population decline, counterurbanisation, collapse of centralized authority and mass migrations of tribes, which had begun in Late Antiquity, continued in the Early Middle Ages; the large-scale movements of the Migration Period, including various Germanic peoples, formed new kingdoms in what remained of the Western Roman Empire. In the 7th century, North Africa and the Middle East—once part of the Byzantine Empire—came under the rule of the Umayyad Caliphate, an Islamic empire, after conquest by Muhammad's successors. Although there were substantial changes in society and political structures, the break with classical antiquity was not complete.
The still-sizeable Byzantine Empire, Rome's direct continuation, survived in the Eastern Mediterranean and remained a major power. The empire's law code, the Corpus Juris Civilis or "Code of Justinian", was rediscovered in Northern Italy in 1070 and became admired in the Middle Ages. In the West, most kingdoms incorporated the few extant Roman institutions. Monasteries were founded; the Franks, under the Carolingian dynasty established the Carolingian Empire during the 8th and early 9th century. It covered much of Western Europe but succumbed to the pressures of internal civil wars combined with external invasions: Vikings from the north, Magyars from the east, Saracens from the south. During the High Middle Ages, which began after 1000, the population of Europe increased as technological and agricultural innovations allowed trade to flourish and the Medieval Warm Period climate change allowed crop yields to increase. Manorialism, the organisation of peasants into villages that owed rent and labour services to the nobles, feudalism, the political structure whereby knights and lower-status nobles owed military service to their overlords in return for the right to rent from lands and manors, were two of the ways society was organised in the High Middle Ages.
The Crusades, first preached in 1095, were military attempts by Western European Christians to regain control of the Holy Land from Muslims. Kings became the heads of centralised nation-states, reducing crime and violence but making the ideal of a unified Christendom more distant. Intellectual life was marked by scholasticism, a philosophy that emphasised joining faith to reason, by the founding of universities; the theology of Thomas Aquinas, the paintings of Giotto, the poetry of Dante and Chaucer, the travels of Marco Polo, the Gothic architecture of cathedrals such as Chartres are among the outstanding achievements toward the end of this period and into the Late Middle Ages. The Late Middle Ages was marked by difficulties and calamities including famine and war, which diminished the population of Europe. Controversy and the Western Schism within the Catholic Church paralleled the interstate conflict, civil strife, peasant revolts that occurred in the kingdoms. Cultural and technological developments transformed European society, concluding the Late Middle Ages and beginning the early modern period.
The Middle Ages is one of the three major periods in the most enduring scheme for analysing European history: classical civilisation, or Antiquity. The "Middle Ages" first appears in Latin in 1469 as media tempestas or "middle season". In early usage, there were many variants, including medium aevum, or "middle age", first recorded in 1604, media saecula, or "middle ages", first recorded in 1625; the alternative term "medieval" derives from medium aevum. Medieval writers divided history into periods such as the "Six Ages" or the "Four Empires", considered their time to be the last before the end of the world; when referring to their own times, they spoke of them as being "modern". In the 1330s, the humanist and poet Petrarch referred to pre-Christian times as antiqua and to the Christian period as nova. Leonardo Bruni was the first historian to use tripartite periodisation in his History of the Florentine People, with a middle period "between the fall of the Roman Empire and the revival of city life sometime in late eleventh and twelfth centuries".
Tripartite periodisation became standard after the 17th-century German historian Christoph Cellarius divided history into three periods: ancient and modern. The most given starting point for the Middle Ages is around 500, with the date of 476 first used by Bruni. Starting dates are sometimes used in the outer parts of Europe. For Europe as a whole, 1500 is considered to be the end of the Middle Ages, but there is no universally agreed upon end date. Depending on the context, events such as the conquest of Constantinople by the Turks in 1453, Christopher Columbus's first voyage to the Americas in 1492, or the Protestant Reformation in 1517 are sometimes used. English historians use the Battle of Bosworth Field in 1485 to mark the end of the period. For Spain, dates used are the death of King Ferdinand II in 1516, the death of Queen Isabella I of Castile in 1504, or the conquest of Granada in 1492. Historians from Romance-speaking countries tend to divide the Middle Ages into two parts: an earlier "High" and late
A great hall is the main room of a royal palace, nobleman's castle or a large manor house or hall house in the Middle Ages, continued to be built in the country houses of the 16th and early 17th centuries, although by the family used the great chamber for eating and relaxing. At that time the word "great" meant big, had not acquired its modern connotations of excellence. In the medieval period the room would have been referred to as the "hall", unless the building had a secondary hall, but the term "great hall" has been predominant for surviving rooms of this type for several centuries, to distinguish them from the different type of hall found in post-medieval houses. Great halls were found in France and Scotland, but similar rooms were found in some other European countries. A typical great hall was a rectangular room between one and a half and three times as long as it was wide, higher than it was wide, it was entered through a screens passage at one end, had windows on one of the long sides including a large bay window.
There was a minstrels' gallery above the screens passage. At the other end of the hall was the dais where the high table was situated; the lord's family's more private rooms lay beyond the dais end of the hall, the kitchen and pantry were on the opposite side of the screens passage. Royal and noble residences had few living rooms until late in the Middle Ages, a great hall was a multifunctional room, it was used for receiving guests and it was the place where the household would dine together, including the lord of the house, his gentleman attendants and at least some of the servants. At night some members of the household might sleep on the floor of the great hall; the hall would have had a central hearth, with the smoke rising through the hall to a vent in the roof. The hearth was used for heating and for some of the cooking, although for larger structures a medieval kitchen would customarily lie on a lower level for the bulk of cooking; the fireplace would have an elaborate overmantel with stone or wood carvings or plasterwork which might contain coats of arms, heraldic mottoes, caryatids or other adornment.
In the upper halls of French manor houses, the fireplaces were very large and elaborate. The great hall had the most beautiful decorations in it, as well as on the window frame mouldings on the outer wall. Many French manor houses have beautifully decorated external window frames on the large mullioned windows that light the hall; this decoration marked the window as belonging to the lord's private hall. It was. In Scotland, six common furnishings were present in the sixteenth century hall: the high table and principal seat. In western France, the early manor houses were centered on a central ground-floor hall; the hall reserved for the lord and his high-ranking guests was moved up to the first-floor level. This was called upper hall. In some of the larger three-storey manor houses, the upper hall was as high as second storey roof; the smaller ground-floor hall or salle basse remained but was for receiving guests of any social order. It is common to find these two halls superimposed, one on top of the other, in larger manor houses in Normandy and Brittany.
Access from the ground-floor hall to the upper hall was via an external staircase tower. The upper hall contained the lord's bedroom and living quarters off one end; the great hall would have an early listening device system, allowing conversations to be heard in the lord's bedroom above. In Scotland these devices are called a laird's lug. In many French manor houses there are small peep-holes from which the lord could observe what was happening in the hall; this type of hidden peep-hole is called a judas in French. Many great halls survive. Two large surviving royal halls are Westminster Hall and the Vladislav Hall in Prague Castle. Penshurst Place in Kent, England has a little altered 14th century example. Surviving 16th and early 17th century specimens in England and Scotland are numerous, for example those at Longleat, Burghley House, Bodysgallen Hall, Muchalls Castle and Crathes Castle; the greater centralization of power in royal hands meant that men of good social standing were less inclined to enter the service of a lord to obtain his protection, the size of the inner household shrank.
As the social gap between master and servant grew, the family retreated to the 1st floor, to private rooms. In fact, servants were not allowed to use the same staircases as nobles to access the great hall of larger castles in early times; the other living rooms in country houses became more numerous and important, by the late 17th century the halls of many new houses were vestibules, passed through to get to somewhere else, but not lived in. Other great halls like that at Bank Hall in Lancashire were downsized to create two rooms; the domestic model applied to Collegiate institutions du
A groin vault or groined vault is produced by the intersection at right angles of two barrel vaults. The word "groin" refers to the edge between the intersecting vaults. Sometimes the arches of groin vaults are pointed instead of round. In comparison with a barrel vault, a groin vault provides good economies of labour; the thrust is concentrated along the groins or arrises, so the vault need only be abutted at its four corners. Groin vault construction was first exploited by the Romans, but fell into relative obscurity in Europe until the resurgence of quality stone building brought about by Carolingian and Romanesque architecture, it was superseded by the more flexible rib vaults of Gothic architecture in the Middle Ages. Difficult to construct neatly because of the geometry of the cross groins, the groin vault required great skill in cutting stone to form a neat arris; this difficulty, in addition to the formwork required to create such constructions, led to the rib vault superseding the groin vault as the preferred solution for enclosing space in Gothic architecture.
The construction method was common on the basement level, such as at Myres Castle in Scotland, or at the ground floor level for the storerooms as at Muchalls Castle in Scotland. While the barrel vault was more common than the groin vault in early architecture, including Roman and earlier civilizations, the Romans developed the groin vault for applications in a variety of structures, some with significant span widths; the first groin vault in Europe was, constructed in Delphi by King Attalos I of Pergamon some time between 241 and 197 BC, quite in 223 BC. Their application of groin vaults to vast halls like the frigidaria in the Baths of Caracalla and Diocletian became influential in church architecture in the Middle Ages; the aspirations of church building reached its zenith and the groin vault was pursued aggressively for its ability to create strength, without massive buttress formations. 20th-century structural engineers have studied the static stress forces of the groin vault design and validated the Romans' foresight in an efficient design to accomplish the multiple goals of minimum materials use, wide span of construction, ability to achieve lateral illumination, avoidance of lateral stresses.
A seminal modern design is the largest European train station, Hauptbahnhof in Berlin, which features an entrance building with a glass-spanned groin vault design. The construction of a groin vault can be understood most by visualising two barrel vault sections at right angles merging to form a squarish unit; the resulting four ribs convey piers. The more complex groin vault is intrinsically a stronger design compared to the barrel vault, since the barrel vault structure must rest on long walls creating less stable lateral stress, whereas the groin vault design can direct stresses purely vertically on the piers. A common association of vaulting in cathedrals of the Middle Ages involves a nave of barrel vault design with transepts of groined vaulting. Rib vaults resemble groin vaults but introduce structural ribs running along the angles which carry much of the weight, making possible much greater variations of proportion. Baths of Caracalla, Italy, early 3rd century AD 32.9 meter high groined structure Charlemagne's Palatine Chapel in Aachen, Germany Santa Maria Maggiore di Firenze, Italy, 11th-century church Basilica of Sant'Ambrogio, Italy Old Cathedral of Coimbra, Portugal, lateral aisles, 12th century Muchalls Castle, ground floor rooms from the 14th century All early Russian palaces, including the Palace of Facets Church of St. Triphon at Ivan III's suburban estate of Naprudnoe, near Moscow, 1490s Three churches of the Rostov Kremlin, 1670s and 1680s Exchange and Provost, South Carolina, 1771 New Orleans Mint, New Orleans, Louisiana, 1838 Aztec Center San Diego State, San Diego, California, 1968 now demolished.
Basilica Minore de San Sebastián in Quiapo, Philippines. Tower house Architectural vault types Steinmetz solid "Groined Vaulting". New International Encyclopedia. 1905
Mortar is a workable paste used to bind building blocks such as stones and concrete masonry units and seal the irregular gaps between them, sometimes add decorative colors or patterns in masonry walls. In its broadest sense mortar includes pitch and soft mud or clay, such as used between mud bricks. Mortar comes from Latin mortarium meaning crushed. Cement mortar becomes hard. Mortars are made from a mixture of sand, a binder, water; the most common binder since the early 20th century is Portland cement but the ancient binder lime mortar is still used in some new construction. Lime and gypsum in the form of plaster of Paris are used in the repair and repointing of buildings and structures because it is important the repair materials are similar to the original materials; the type and ratio of the repair mortar is determined by a mortar analysis. There are several types of cement additives; the first mortars were made of 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 humans using a form of mortar was at the Mehrgarh of Baluchistan in Pakistan, built of sun-dried bricks in 6500 BCE. The ancient sites of Harappan civilization of third millennium BCE are built with kiln-fired bricks and a gypsum mortar. Gypsum mortar called plaster of Paris, was used in the construction of the Egyptian pyramids and many other ancient structures, it is made from gypsum. It is therefore easier to make than lime mortar and sets up much faster which may be a reason it was used as the typical mortar in ancient, brick arch and vault construction. 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 Egyptian pyramids, the mortar was made of either gypsum or lime. Gypsum mortar was 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.
Gypsum cement, "light grey and contained sand, traces of calcium carbonate, a high percentage of lime" was used in the construction of wells, drains and on the exteriors of "important looking buildings." Bitumen mortar was used at a lower-frequency, including in the Great Bath at Mohenjo-daro. 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; the Greeks obtained the volcanic ash from the Greek islands Thira and Nisiros, or from the Greek colony of Dicaearchia near Naples, Italy. The Romans improved the use and methods of making what became known as pozzolanic mortar and cement; the Romans used a mortar without pozzolana using crushed terra cotta, introducing aluminum oxide and silicon dioxide into the mix.
This mortar was not as strong as pozzolanic mortar, because it was denser, it better resisted penetration by water. Hydraulic mortar was not available in ancient China due to a lack of volcanic ash. Around 500 CE, sticky rice soup was mixed with slaked lime to make an inorganic−organic composite sticky rice mortar that had more strength and water resistance than lime mortar, it is not understood how the art of making hydraulic mortar and cement, perfected and in such widespread use by both the Greeks and Romans, was lost for two millennia. During the Middle Ages when the Gothic cathedrals were being built, the only active ingredient in the mortar was lime. Since cured lime mortar can be degraded by contact with water, many structures suffered from wind blown rain over the centuries. Ordinary Portland cement mortar known as OPC mortar or just cement mortar, is created by mixing powdered Ordinary Portland Cement, fine aggregate and water, it was invented in 1794 by Joseph Aspdin and patented on 18 December 1824 as a result of efforts to develop stronger mortars.
It was made popular during the late nineteenth century, had by 1930 became more popular than lime mortar as construction material. The advantages of Portland cement is that it sets hard and allowing a faster pace of construction. Furthermore, fewer skilled workers are required in building a structure with Portland cement; as a general rule, Portland cement should not be used for the repair or repointing of older buildings built in lime mortar, which require the flexibility and breathability of lime if they are to function correctly. In the United States and other countries, five standard types of mortar are used for both new construction and repair. Strengths of mortar change based on the ratio of cement and sand used in mortar; the ingredients and the mix ratio for each type of mortars are specified under the ASTM standards. These premixed mortar products are designated by one of the five letters, M, S, N, O, K. Type M mortar is the strongest, Type K the weakest; these type