It was in the area of architecture that Roman art produced its greatest innovations. Because the Roman Empire extended over so great an area and included so many urbanized areas, Roman engineers developed methods for city building on a grand scale, including the use of concrete. The concrete core was covered with a plaster, brick, stone, or marble veneer, and decorative polychrome and gold-gilded sculpture was often added to produce a dazzling effect of power and wealth
Massive buildings like the Pantheon and the Coliseums could never have been constructed with previous materials and methods. Though concrete had been invented a thousand years earlier in the Near East, the Romans extended its use from fortifications to their most impressive buildings and monuments, capitalizing on the material's strength and low cost. Because of these methods, Roman architecture is legendary for the durability of its construction; with many buildings still standing, and some still in use, mostly buildings converted to churches during the Christian era. Many ruins, however, have been stripped of their marble veneer and are left with their concrete core exposed, thus appearing somewhat reduced in size and grandeur from their original appearance, such as with the Basilica of Constantine.
As Roman power grew in the early empire, the first emperors inaugurated wholesale During the Republican era, Roman architecture combined Greek and Etruscan elements, and produced innovations such as the round temple and the curved arch, the first emperors inaugurated wholesale leveling of slums to build grand palaces on the Palatine Hill and nearby areas, which required advances in engineering methods and large scale design. Roman buildings were then built in the commercial, political, and social grouping known as a forum, that of Julius Caesar being the first and several added later, with the Forum Romano being the most famous. The greatest arena in the Roman world, the Coliseums, was completed around 80 AD.
At the far end of that forum. It held over 50,000 spectators, had retractable fabric coverings for shade, and could stage massive spectacles including huge gladiatorial contests and mock naval battles. This masterpiece of Roman architecture epitomizes Roman engineering efficiency and incorporates all three architectural orders-Doric, Ionic, and Corinthian. Less celebrated but just as important if not more so for most Roman citizens, was the five-story insular or city block, the Roman equivalent of an apartment building, which housed tens of thousands of Romans.
It was during the reign of Trajan (98-117 AD.) and Hadrian (117-138 AD.) that the Roman Empire reached its greatest extent and that Rome itself was at the peak of its artistic glory achieved through massive building programs of monuments, meeting houses, gardens, aqueducts, baths, palaces, pavilions, sarcophagi, and temples. The Roman use of the arch, the use of concrete building methods, the use of the dome all permitted construction of vaulted ceilings and enabled the building of these public spaces and complexes, including the palaces, public baths and basilicas of the "Golden Age" of the empire. Outstanding examples of dome construction include the Pantheon, the Baths of Diocletian, and the Baths of Caracalla.
The Pantheon (dedicated to all the planetary gods) is the best preserved temple of ancient times with an intact ceiling featuring an open "eye" in the center. The height of the ceiling exactly equals the interior diameter of the building, creating an enclosure that could contain giant sphere. These grand buildings later served as inspirational models for architects of the Italian Renaissance, such as Brunelleschi. By the age of Constantine, the last great building programs in Rome took place, including the erection of the Arch of Constantine built near the Coliseum, which recycled some stone work from the forum nearby, to produce an eclectic mix of styles,
Benton, Jeanette Refold and DiYanni, Robert. Arts and Culture. Volume 1. Prentice-Hall, 1998. New Jersey, United States.
Jonson, H. W. The History of Art, Harry N. Abrams, New York, 1986,
Hyun, Marie Sue. "The Art of Dream Healing." DK Publishing, 1998. New York, New York.
Toynbee, J. M. C. (December 1971). "Roman Art". The Classical Review 21 (3):
Sybille Ebert-Stiffener, Still Life: A History, Harry N. Abrams, New York, 1998, p. 15
Ebert-Stiffener, p. 16
-A brief history on the hydraulic mortar discovery discovered in the roman era.
The Romans are generally credited as being the first concrete engineers, but archaeological evidence says otherwise. Archaeologists have found a type of concrete dating to 6500 B.C., when stone-age Syrians used permanent fire pits for heating and cooking. These fire pits, built from area limestone, showed a primitive form of calcimine on the exterior faces of the limestone rocks that lined the fire pits and lead to the accidental discovery of lime as a fundamental building material. The newly discovered technology was widely used in Syria, as central lime-burning kilns were constructed to supply mortar for rubble-wall house construction, concrete floors, and waterproofing cisterns.
Lime, quicklime, and burnt lime are the common names for calcium oxide, CaO, a grayish-white powder. Today over 150 important industrial chemicals requires the use of lime in order to be manufactured.. In fact, only five other raw materials (salt, coal, sulfur, air, and water) are used in greater amounts. Lime is used in glass, cement, brick, and other building materials; as well as in the manufacture of steel, aluminum, and magnesium, poultry feed; and in the processing of cane and sugar beet juices. It is strongly caustic and can severely irritate human skin and mucous membrane. Thus, the discovery of lime as a building material opened the door for many other improvements as well.
In Europe, archaeological evidence for early use of concrete is also found from along the banks of the Danube River in Yugoslavia, where in approximately 5600 B.C. it was used to make floors for huts.
In China, as far back as 3000 BC, there is evidence of a type of cement used in the Gansu Province of northwest China.
The Egyptians used cement as far back as 2500 B.C. Some scholars believe that a cementing material produced from either a lime concrete or burnt gypsum was used in forming the Great Pyramid at Giza. The earliest known illustration (dating to about 1950 B.C.) of concrete being used in Egypt is shown in a mural on a wall in Thebes. Archeologists have long thought that the Egyptians were masters of the stone as stone artifacts (hard stone vessels, statues) made of metamorphic schist, diorite and basalt were produced. These smooth and glossy stone artifacts (between 4.000 and 5.000 years old) bear no trace of tool marks. Some archeologists believe that the ancient Egyptian artists knew how to convert ores and minerals into a mineral binder for producing stone artifacts. They believe that many of the Egyptian statues were not carved from rock, but rather were cast in molds, and are synthetic stone statues.
The first evidence for this comes from a new deciphering of the C-14 Artisan Stele (dating 2.000 BC, Louvre Museum, Paris). The steel is the autobiography of the sculptor Artisan who lived under one of the Mentuhotep Pharaohs, 11th. Dynasty. The stele C-14 of the Louvre has been often studied. Yet many of its expressions pertain to the domain of stone technology and have been tentatively translated in the past with terms differing so widely that the translators were obviously not able to understand the described technology. According to sculptor Artisan, cast man-made stone was a secret knowledge. (Egyptian Made-Made Stone Statues in 2000 B.C.: Deciphering the Artisan Stele,(Louvre C14 6 pages) Was this material a type of cement?
Some scientists are now proposing that the pyramids were made of poured stone, rather than quarried stone. From a geological point of view, the Giza Plateau is an outcrop of the Middle Eocene Mokkatam Formation. Yet, the outcrop that dips into the wadi, where the quarries are located and also the trench around the Sphinx and the Sphinx body, consist of softer thickly bedded marly nummulite limestone layers with a relative high amount of clay. The amount of water-sensitive parts, expressed as weight percent of stone, is strikingly very high, ranging between 5.5% to 29%. It is obvious that the builders took advantage of the thickly bedded softer lime stones. The disaggregated muddy material was ready for geopolymeric reagglomeration. Perhaps the biggest surprise encountered in this study deals with the hieroglyphic verbs for to build, namely khusi (Gardiner's list A34). The sign khusi represents a man pounding or packing material in a mold. This is one of the oldest Egyptian hieroglyphs. (Construction of the Egyptian Great Pyramids, 2500 B.C., with Agglomerated Stone)
It was the Romans, however, who used cement in large amounts, for huge building projects. Early Roman use of cement dates back to around 300 B.C. Since that period, the Romans steadily improved their concrete technology; they also gave it its name. The word "concrete" comes from the Latin 'concretes', meaning "grown together" or "compounded".
Roman concrete structures still stand today. Both the Coliseums (complete in 82 A.D.) and the Pantheon (completed in 128 A.D.) contain large amounts of concrete. The Basilica of Constantine and the foundations of the Forum buildings also were constructed of concrete. Since Roman cement has been so well studied, it will give us a basis for understanding the issues that are important in investigating Nabataea cement.
Adam, J. P., La Construction Romaine. Grand Manuals Picard, Paris, 1984, p.86-87.
Azaroff, L. V., Introduction to Solids. McGraw Hill Book Co., New York, 1960, p. 431
Azbe, V.J., Theory and Practice of Lime Manufacture. Rock Products Publisher, 1946, p. 129.
Bailey, C., the Legacy of Rome. Clareton Press, Oxford, 1968, p. 439
Bailey, K. C., Plinus Secundus-The Elder Pliny. Arnold Publisher, London, 1929, p. 145.
Balsdon, J. P. V. D., the Romans. Basic Books, Inc., New York, 1965, p. 183.
Banks R. F., and M. L. Kennedy, The Technology of Cement and Concrete. John Wiley & Sons, New York, 1955, p. 16.
-Discussing the hydraulic mortar structure.
The damage of concrete surfaces under water flow, caused by abrasive action of waterborne solid particles, is one of the major issues when designing the operation of hydraulic structures. The issue is especially severe in spillways and outlets of dams on rivers with significant torrential character. The term "abrasion" in hydraulic structures is used for the process of disintegration of exposed concrete surfaces, resulting from loads arising from sediment transport.1 The rate of disintegration of the concrete surface largely depends on the transport capacity of water and the ways of transport of solid matter.2,3 Accordingly, the abrasion of concrete can be divided into several phases. In the initial phase, the process of abrasion is caused by sediment transport. The damage to concrete structures thus results from polishing/ milling due to rolling or sliding of sediments (solid particles) against the surface. By increased transport capacity, the small particles start to move in suspension, and large solid particles move by way of rebound. At this phase, the abrasion process depends on bed load transport or suspended matter. In addition to the milling action of concrete surfaces, damage due to the impact of solid particles against the surface can be observed. By increased transport capacity, the size and quantity of rebounding particles increase significantly; and, simultaneously, the pulsations of pressures in the water increase.
This contributes to the intensity of abrasion. The resulting damage to the concrete surfaces is related to the increase in size of the solid particles and intensity of impacts against the bottom, where the initial damages occur, which represent, with progressing processes, the core of progressive spreading of the damage in the direction of the water current.4
When designing concretes in hydraulic structures, it should be emphasized that there is no general criterion for defining abrasion resistance. Usually, abrasion resistance of concretes is assessed based on a set of parameters that define the single mechanical properties of concrete, such as compressive strength, tensile strength, aggregate strength, use of special cements, modulus of elasticity, water-cement ratio (w/c), surface polishing, concrete cure, and cement additives (fly ash and fibers) connected with investigating methods that more or less realistically simulate abrasive processes.
Hydraulic lime is a type of lime, or calcium carbonate, which is used to make mortar and plaster products. The lime is heated, and then mixed with an aggregate material like sand or stone. Once this mixture is blended with water to form mortar, it can be used in many types of masonry construction projects. The mortar can be placed between bricks or blocks to bind them together, or may even be applied to the surface of the masonry to create a plaster or stucco-like application.
A specialized form of limestone is used to make hydraulic lime. The limestone is mixed with clay then fired in a kiln to high temperatures. This process removes much of the moisture from the lime and also produces mineral by-products known as silicates. The remaining limestone and silicates are combined to form hydraulic lime.
To understand how hydraulic lime works, it is important to first understand how traditional hydrated lime works. When hydrated lime is mixed with water to form mortar, it has a consistency similar to peanut butter. As the mortar reacts with the air, it absorbs carbon dioxide, causing it to harden or cure. Hydraulic lime mortar, or the other hand, begins to harden when it is exposed to water. Over time, it will also absorb carbon dioxide from the air to experience a second phase of hardening or curing. Due to these differing reactions, hydrated lime and hydraulic lime are very different products and are not interchangeable.
Hydraulic lime offers a number of benefits over traditional lime mortar blends. The most important is its ability to cure and harden when wet, which means it can be used in many applications where other mortar products would fail. It also has low elasticity, resulting in fewer cracks due to expansion and contraction. Hydraulic lime is also very porous, allowing excess moisture to escape rather than collecting inside the wall structure. This makes it very popular for historic preservation applications, where traditional hydrated lime would crack or crumble over time due to trapped moisture.
Marceau, Jo. Art: A World History. DK Publishing, 1998. New York, New York.
Montverde, Mario. The Book of Art. Volume 1: The Origins of Western Art. Grolier 1967. Milan, Italy.
Mutagens, Patrick. The World's Great Architecture. Excalibur, 1981. New York, New York.
Piper, David. The Illustrated Library of Art, Portland House, New York, 1986, ISBN0-517-62336-6
Turner, Jane. The Dictionary of Art. Volumes 26 and 27. Macmillan, 2002. Hong Kong. Piper, p. 252
-Comparing between the hydraulic mortar used
in the Roman era and the mortar used nowadays
chemically.
Concrete is a mixture of cement, sand and gravel. That is, cement is the glue of concrete. Now let's talk about cement. Cement begins with lime. Lime is the First Cement. It is a substance used since ancient times to make useful things like plaster and mortar. Lime is made by burning, or calcining, limestone-and that's how limestone gets its name. Chemically, lime is calcium oxide (CaO) and is made by roasting calcite (CaCO3) to drive off carbon dioxide (CO2). That CO2, a greenhouse gas, is produced in great quantities by the cement industry.
Lime is also called quicklime or calx (from Latin, where we also get the word calcium). In old murder mysteries, quicklime is sprinkled on victims to dissolve their bodies because it is very caustic.
Mixed with water, lime slowly turns into the mineral portlandite in the reaction CaO + H2O = Ca (OH)2. Lime is generally slaked, that is, mixed with an excess of water so it stays fluid. Slaked lime continues to harden over a period of weeks. Mixed with sand and other ingredients, slaked lime cement can be packed between stones or bricks in a wall (as mortar) or spread over the surface of a wall (as render or plaster). There, over the next several weeks or longer, it reacts with CO2 in the air to form calcite again-artificial limestone!
Concrete made with lime cement is known from archaeological sites in both the New and Old World, some more than 5000 years old. It works extremely well in dry conditions. It has two drawbacks:
Lime cement takes a long time to cure, and while the ancient world had lots of time, today time is money.
Lime cement does not harden in water but stays soft, that is, it is not a hydraulic cement. So there are situations where it cannot be used.
Around 1000 BCE, the ancient Greeks were the first to have a lucky accident, mixing lime with fine volcanic ash. Ash can be thought of as naturally calcined rock, leaving silicon in a chemically active state like the calcium in calcined limestone. When this lime-ash mixture is slaked, a whole new substance is formed: calcium silicate hydrate or what cement chemists call C-S-H (approximately SiCa2O4 · xH2O). In 2009, researchers using numerical modeling came up with the exact formula: (CaO) 1.65(SiO2)(H2O)1.75.
C-S-H is still a mysterious substance today, but we know it is an amorphous gel without any set crystalline structure. It hardens fast, even in water. And it is more durable than lime cement.
While lime cement continued in use throughout the Dark and middle Ages, true hydraulic cement was not rediscovered until the late 1700s. English and French experimenters learned that a calcined mixture of limestone and clay stone could be made into hydraulic cement. One English version was dubbed "Portland cement" for its resemblance to the white limestone of the Isle of Portland, and the name soon extended to all cement made by this process.
Shortly thereafter, American makers found clay-bearing lime stones that yielded excellent hydraulic cement with little or no processing. This cheap natural cement made up the bulk of American concrete for most of the 1800s, and most of it came from the town of Rosendale in southern New York. Rosendale was practically a generic name for natural cement, although other manufacturers were in Pennsylvania, Indiana and Kentucky. Rosendale cement is in the Brooklyn Bridge, the U.S. Capitol building, most 19th-century military buildings, the base of the Statue of Liberty and many other places. With the rising need to maintain historic structures using historically appropriate materials, Rosendale natural cement is being revived.
Today limestone and clay-containing rocks are sintered-roasted together at nearly melting temperature-at 1400° to 1500°C. The product is a lumpy mixture of stable compounds called clinker. Clinker contains iron (Fe) and aluminum (Al) as well as silicon and calcium, in four main compounds:
Alite (Ca3SiO5)
Belite (Ca2SiO4), known to geologists as larnite
Aluminate (Ca3Al2O6)
Ferrite (Ca2AlFeO5)
Clinker is ground to powder and mixed with a small amount of gypsum, which slows down the hardening process. And that is Portland cement.
Making Concrete, Cement is mixed with water, sand and gravel to make concrete. Pure cement is useless because it shrinks and cracks; it's also much more expensive than sand and gravel. As the mixture cures, four main substances are produced:
C-S-H
Portlandite
Ettringite (Ca6Al2(SO4)3(OH)12 · 26H2O; includes some Fe)
Monosulfate ([Ca2(Al,Fe)(OH)6] · (SO4,OH,etc) · xH2O)
The details of all this are an intricate specialty, making concrete as sophisticated a technology as anything in your computer. Yet basic concrete mix is practically stupidproof, simple enough for you and me to use
Roman concrete, like any concrete, consists of an aggregate and hydraulic mortar - a binder mixed with water that hardens over time. The aggregate varied, and included pieces of rock, ceramic tile, and brick rubble from the remains of previously demolished buildings. Reinforcing elements, such as steel rebar, were not used.
Modern hydraulic cements began to be developed from the start of the Industrial Revolution (around 1800), driven by three main needs:
Hydraulic render (stucco) for finishing brick buildings in wet climates.
Hydraulic mortars for masonry construction of harbor works, etc., in contact with sea water.
Development of strong concretes.
Hydraulic limes were favored for this, but the need for a fast set time encouraged the development of new cements. Most famous was Parker's "Roman cement". This was developed by James Parker in the 1780s, and finally patented in 1796. It was, in fact, nothing like any material used by the Romans, but was"Natural cement" made by burning septaria - nodules that are found in certain clay deposits, and that contain both clay minerals and calcium carbonate. The burnt nodules were ground to a fine powder. This product, made into a mortar with sand, set in 5-15 minutes. The success of "Roman Cement" led other manufacturers to develop rival products by burning artificial mixtures of clay and chalk.
-Discussing the structure of the Roman buildings.
Social elements such as wealth and high population densities in cities forced the ancient Romans to discover new (architectural) solutions of their own. The use of vaults and arches together with a sound knowledge of building materials, for example, enabled them to achieve unprecedented successes in the construction of imposing structures for public use.
Examples include the aqueducts of Rome, the Baths of Diocletian and the Baths of Caracalla, the basilicas and Colosseum. They were reproduced at smaller scale in most important towns and cities in the Empire. Some surviving structures are almost complete, such as the town walls of Lugo in Hispania Tarraconensis, or northern Spain.
The Ancient Romans intended that public buildings should be made to impress, as well as perform a public function. The Romans did not feel restricted by Greek aesthetic axioms alone in order to achieve these objectives. The Pantheon is a supreme example of this, particularly in the version rebuilt by Hadrian, which remains perfectly preserved, and which over the centuries has served, particularly in the Western Hemisphere, as the inspiration for countless public buildings. The same emperor left his mark on the landscape of northern Britain when he built a wall to
Conclusion
Now we can conclude that the first mortars were made from mud or clay. These materials were used because of availability and low cost. The Egyptians utilized gypsum mortars to lubricate the beds of large stones when they were being moved into position. However, these materials did not perform well in the presence of high levels of humidity and water.
It was discovered that limestone, when burnt and combined with water, produced a material that would harden with age. The earliest documented use of lime as a construction material was approximately 4000 B.C. when it was used in Egypt for plastering the pyramids. The beginning of the use of lime in mortars is not clear. It is well documented, however, that the Roman Empire used lime based mortars extensively. Vitruvius, a Roman architect, provided basic guidelines for lime mortar mixes.
"… When it [the lime] is slaked, let it be mingled with the sand in such a way that if it is pit sand three of sand and one of lime is poured in; but if the same is from the river or sea, two of sand and one of lime is thrown together. For in this way there will be the right proportion of the mixture and blending."
Mortars containing only lime and sand required carbon dioxide from the air to convert back to limestone and harden. Lime/sand mortars hardened at a slow rate and would not harden under water. The Romans created hydraulic mortars that contained lime and a pozzolan such as brick dust or volcanic ash. These mortars were intended be used in applications where the presence of water would not allow the mortar to carbonate properly. Examples of these types of applications included cisterns, fish-ponds, and aqueducts.
The most significant developments in the use of pozzolans in mortars occurred in the 18th century. It was discovered that burning limestone containing clays would produce a hydraulic product. In 1756, James Smeaton developed perhaps the first hydraulic lime product by calcining Blue Lisa limestone containing clay. An Italian pozzolanic earth from Cavite Vichada was also added to provide additional strength. This mortar mixture was used to build the Eddystone Lighthouse. James Parker patented a product called Roman cement or natural cement in 1796. Natural cement was produced by burning a mixture of limestone and clay together in kilns similar to those used for lime. The resulting product was ground and stored in waterproof containers. Typically, natural cements had higher clay contents than hydraulic lime products, which allowed for better strength development. Natural cement mortar was used in construction where masonry was subjected to moisture and high levels of strength were needed.
Joseph Aspdin, an English mason/builder patented a material called Portland cement in 1824. Portland cement consisted of a blend of limestone, clay and other minerals in carefully controlled proportions which were calcined and ground into fine particles. Though some Portland cement was imported from Europe, it was not manufactured in the United States until 1871. The consistency and higher strength levels of Portland cement allowed it to replace natural cements in mortars. Portland cement by itself had poor workability. Portland cement combined with lime provided an excellent balance between strength and workability. The addition of Portland cement to lime mortars increased the speed of the construction process for masonry building due to faster strength development. Mix designs incorporating different amounts of lime and Portland cement were developed. In 1951, ASTM published a Standard Specification for Unit Masonry (C270-51). This specification allowed combinations of cement and lime to be specified by volume proportions or mortar properties. ASTM C270 is still in use today. This standard identifies five mortar types based on the phrase MASON WORK S. Type M cement/lime blends have the highest compressive strength and Type K has the lowest.
Until approximately 1900, lime putty was used in construction applications. Limestone was burned in small kilns often built on the side of a hill to facilitate loading. Wood, coal and coke were used as fuel. The quicklime produced from these kilns was added to water in a pit or metal trough and soaked for an extended period of time. The time required for soaking was dependent on the quality of the quicklime and could range from days to years. It was generally thought that the longer the quicklime was soaked, the better it would perform. The Standard Specification for Quicklime for Structural Purposes was developed in 1913. After the turn of the century, the use of hydrated lime products began. Water was added to quicklime at the manufacturing plant to reduce the amount of time required for soaking at the jobsite. In the late 1930's, the production of pressure hydrated dolomitic lime products began. These products required only short periods of soaking (20 minutes or less) prior to use. In 1946 the Standard Specification for Hydrated Lime for Masonry Purposes (ASTM C207) was published. This standard identified two and later four types of lime products that could be used in masonry applications.
Lime products have played a significant role in masonry construction for thousands of years. Prior to 1930, most masonry construction utilized lime based mortars. Lime has proven performance that is demonstrated by structures, such as the Great Wall of China, which have lasted for hundreds of years. The reasons for using lime in mortar 2000 years ago still remain valid today.
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