Roman cement

The early Egyptians used a building material very similar to cement. Romans used a building material obtained by mixing lime and volcanic ash. They used it to pave roads and build other structures throughout Europe. 

Portland cement is classified as a hydrauHc cement, ie, it sets or cures in the presence of water. The term Portland comes from its inventor, Joseph Aspdin, who in 1824 obtained a patent for the combination of materials referred to today as Portland cement. He named it after a grayish colored, natural limestone quarried on the Isle of Portland, which his cured mixture resembled. Other types of hydrauHc cements based on calcium materials were known for many centuries before this, going back to Roman times. Portland cement is not an exact composition but rather a range of compositions, which obtain the desired final properties. The compounds that make up Portland cements are calcium siHcates, calcium aluminates, and calcium aluminoferrites (see ). 

Hydrometallurigcal Processes. In hydrometaHurgical processes, metal values and by-products are recovered from aqueous solution by chemical or electrolytic processes. Values are solubilized by treating waste, ore, or concentrates. Leaching of copper ores in place by rain or natural streams and the subsequent recovery of copper from mnoff mine water as impure cement copper have been practiced since Roman times. Most hydrometaHurgical treatments have been appHed to ores or overburden in which the copper was present as oxide, mixed oxide—sulfide, or native copper. PyrometaHurgical and hydrometaHurgical processes are compared in Reference 34. 

Petrifix A process for solidifying aqueous wastes, converting them to a solid form suitable for landfill. Cementitious additives are used, based on the compositions used by the Romans for making Pozzolanic cements. Developed by Pec-Engineering, Paris, France. In 1979 it had been used in France and Germany. 

Lime is one of the oldest materials known to humankind. It was used by Romans, Greeks, and Egyptians for the production of cement and was employed in agriculture as well. One of the first things done by American settlers was to set up a lime kiln for the calcining or heating of limestone. 

Nonhydraulic cements were among the most common of the ancient cements. The relatively high solubilities of portlandite (Ca[OH]2) and gypsum means that they deteriorate rapidly in moist or wet environments. Many decades ago, the Romans used lime-based cements and mortars (cement plus sand) by ramming the wet pastes... 

It is likely that, during the early Roman period, silica and alumina, as well as volcanic earths, were used as cements. Portland cement is made from finely ground limestone and finely divided clay to give a burned product containing 70% CaO, 20% Si02, 4% FeA, and 4% A1203, plus smaller amounts of minor oxides (e.g., NazO, K20, MgO, etc.). 

Boesel, L. F., Mano, J. F., Elvira, C., San Roman, J., Reis, R. L. (2003). Hydrogels and hydrophilic partially degradable bone cements based on biodegradable blends incorporating starch. In E. Chiellini (Ed.), Biodegradable Polymers and Plastics. Kluwer Academic, Dordrecht. 

The Romans pioneered the use of hydraulic, or water-cured, cement. Its unique chemical and physical properties produced a material so lasting that it stands today in magnificent stmctures like the Pantheon. Yet the formula was forgotten in the first few centuries after the fall of the Roman Empire and wasn t rediscovered until 1824 as Portland cement. One Roman version was based on a burned mixture of two major components volcanic ash—called pozzolana—from Mount Vesuvius, which destroyed Pompeii and nearby towns in... 

A.D. 79 and calcium carbonate, the stuff of seashells, chalk, and limestone. Adding water to these sets off a complex set of chemical reactions that convert the gritty pasty stuff into what is essentially artificial stone. The nineteenth-century rediscovery of Roman cement, the aforementioned Portland cement, is made from a combination of burned limestone, clay, and water. It is the single most heavily used human-made material on earth. 

Lime kilns are frequently associated with cement-making.7 The lime-sand cements in use since Roman times gain mechanical strength from the slow reaction of Ca(OH)2 with CO2 of the air to form interlocking crystals of CaCC>3. The sand acts primarily as a matrix around which this process occurs. 

Below the sediments disrupted by cultivation, a unit (Unit A) was found that was about 120 cm thick and that contained a disorderly mixture (almost an inverse time sequence) of Roman, Pharaonic, and Predynastic sherds. The next 15 cm or so was a clay-rich Nile silt (Unit B) in which there was a normal ceramic sequence with sherds dating from about 300 B.C. to about 2500 B.C. Table I describes the typical core sample. The layers of sediments were compacted and, in some cases, partially hardened by a calcareous cement, but in all cases, the samples could be easily crumbled. 

The nature of mortar has changed considerably over time. The primitive clay based mortars gave way to the lime-sand formulation of the Romans with additions of plaster, crushed brick, and/or volcanic earth (pozzolan). The rediscovery of natural cements occurred in the eighteenth century and finally Portland cement was developed. Mortars in use changed accordingly to include the new products. In each case the type, size and amount of charge added in the mix has a large influence on properties such as the bulk density and porosity of the final product. 

When the calcium carbonate, CaC03, in limestone is heated to a high temperature, it decomposes into calcium oxide (called lime or quick lime) and carbon dioxide. Lime was used by tbe early Romans, Greeks, and Egyptians to make cement and is used today to make over 150 different chemicals. In another reaction, calcium oxide and water form calcium hydroxide, Ca(OH)2 (called slaked lime), used to remove the sulfur dioxide from smoke stacks above power plants burning bigb-sulflir coal. The equations for all these reactions are below. Determine the oxidation number for each atom in the equation and identify whether the reactions are redox reaction or not. For each redox reaction, identify what is oxidized and what is reduced. 

Poz/.olana has been used since ancient times to obtain, in mixture with Ca(OH)2, hydraulic mortars, sometimes referred to as Roman cement, characterised by a memorable durability, which allows some civil works of about two thousands years ago be still preserved nowadays (e.g., the Pantheon in Rome) [62]. 

The application of natural zeolites in the field of cement manufacture is destined to grow in the next years. In fact, the next revolution in materials of construction is to go back to the past. The current concrete construction practice is reportedly unsustainable, because the present production of about 1.7 x 109 tpy portland cement has a not negligible environmental impact from standpoint of energy consumption and global warming. So, the expected trend in the concrete industry in the next years is to recur to ancient practices, such as that to re-usc the Roman concretes. This would increase the resort to raw, recycled and waste materials, enabling cost reduction and manufacture of environment-friendly products [117,118]. 

Silica has played a key role since the beginning of civilization, first in flint for tools and weapons and in clay and sand for pottery. The high strength and durability of Roman cement 2000 years ago is now known to be due to the use of a special volcanic ash that is an almost pure form of amorphous colloidal silica. Today there is active research on the use of the somewhat similar silica fume from electric furnaces to make a super-strong Portland cement. 

Hydraulically setting cements were first developed by the Greeks and Romans [B.69]. It was found that, after the addition of volcanic ash (pozzolana) to the slaked lime and sand, a mortar was obtained that possessed superior strength. This was discovered by the Greeks (700-600 BC) and later passed on to the Romans (150 BC) who called it Caementum. It was used, for example, for the construction of the Colosseum in Rome. 

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