Genuine Roman Cement Or pozzuolana, from the neighborhood of Vesuvius, is a peculiar mixture of silica, clay, and lime, which has been calcined by the volcano. It it used mixed with lime and sand. The following is the formula of Vitruvius: 12 parts pozzuolana well powdered, 6 sharp sand well washed, 9 rich lime, recently slaked. It has the power of rapidly hardening under water.
Artificial Portland Cement One hundred lbs. of pure, dry chalk is moistened and ground in a mill with excess of water; to this is added 137 1/2 lbs. of pure alluvial clay, and the two are thoroughly incorporated. The mixture is made into balls, which are dried and calcined in an ordinary lime-kiln.
Rosendale Cement Is made by calcining the limestone or cement-stone, found above the Potsdam sandstone and below the Utica slate of the New York survey. It consists of silica, magnesia, alumina, oxide of iron, with some salts of potash and soda. The stone is found in eastern New York, New Jersey, Pennsylvania and Virginia.
Artificial Hydraulic Cements Are made 1, by combining thoroughly slaked lime with from 10 to 40 per cent. unburnt clay, and burning the mixture in a kiln; 2, by grinding clay and chalk as directed above for Portland Cement; 3, by making artificial pozzuolana from calcareous sand and clay, and calcining it, 4, by the use of silicate of soda: 8 or 10 per cent. of a solution of the consistence of thin syrup, is to be mixed with mortar of fat lime.
Cement for Rooms A coat of oxide of zinc (zinc white) mixed with size, is applied to the wall, ceiling or wainscot; over this, one of chloride of zinc, prepared in the same way. The two unite and form a cement smooth and polished as glass.
Parolic Cement Take unsalted curd of skimmed milk, press the whey out, dry and pulverize, and warm over a stove. Of this, 90 parts; caustic quicklime, in fine powder, 10 parts; powdered camphor, 1 part. Mix intimately and keep in small bottles corked perfectly tight. To use, mix the required amount with water with a palette-knife, and apply immediately.
To make Cement for Floors Earthen floors are commonly made of loam; and sometimes, especially to make malt on, of lime and brooksand, and gun-dust or anvil-dust from the forge. The manner of making earthen floors for plain country habitations is as follows: take 2/3 lime and 1/3 coal-ashes well sifted, with a small quantity of loam clay; mix the whole together and temper it well with water, making it up into a heap; let it lie a week or 10 days and then temper it over again. After this, heap it up for 3 or 4 days, and repeat the tempering very high till it becomes smooth, yielding, tough and gluey. The ground being then levelled, lay the floor therewith about 2 1/2 or 3 in. thick, making it smooth with a trowel. The hotter the season is, the better: and when it is thoroughly dried, it will make the best floor for houses, especially malt-houses.
Pew's Composition for Roofing Buildings Take the hardest and purest limestone (white marble is to be preferred), free from sand, clay or other matter; calcine it in a reverberatory furnace, pulverize and pass through a sieve. One part, by weight, is to be mixed with 2 parts of clay well baked and similarly pulverized, conducting the whole operation with great care. This forms the first powder. The second is to be made of 1 part of calcined and pulverized gypsum, to which is added 2 parts of clay baked and pulverized. These two powders are to be combined and intimately incorporated, so as to form a perfect mixture. When it is to be used, mix it with about 1/4 part of its weight of water, added gradually, stirring the mass well the whole time, until it forms a thick paste, in which state it is to be spread like mortar upon the desired surface. It becomes in time as hard as stone, allows no moisture to penetrate and is not cracked by heat. When well prepared it will last any length of time. When in its plastic or soft state, it may be colored of any desired tint.
Zeiodelite Zeiodelite is made by mixing together 19 lbs. of sulphur and 42. lbs. of pulverized stoneware and glass. The mixture is exposed to a gentle heat, which melts the sulphur, and then the mass is stirred till it becomes thoroughly homogeneous, when it is run into suitable moulds and allowed to cool. This preparation is proof against acids in general, whatever their degree of concentration, and will last an indefinite time. It melts at about 248, and may be reemployed without loss of any of its qualities, whenever it is desirable to change the form of an apparatus, by melting at a gentle heat and operating as with asphalte. At 230° it becomes as compact as stone, and therefore preserves its solidity in boiling water. Slabs of zeiodelite may be joined by introducing between them some of the paste heated to 392°, which will melt the edges of the slabs, and when the whole becomes cold it will present one uniform piece. Chambers lined with zeiodelite, in place of lead, the inventor says, will enable manufacturers to produce acids free from nitrate and sulphate of lead. The cost will be only one-fifth the price of lead. The compound is also said to be superior to hydraulic lime for uniting stone and resisting the action of water.
To make Cement for Canals Take 1 part of iron filings, reduced to sifted powder, 3 parts of silica, 4 parts of red clay, the same quantity of pulverized brick, and 2 parts of hot lime; the whole measured by weight and not by bulk. Put the mixture into a large wooden tub, in order that nothing foreign may be introduced into it. If sufficient water is poured out to extinguish the lime and give a degree of liquidness to the cement, and if all the component parts are briskly stirred, a great degree of heat will be emitted from the lime, and an intimate union formed by the heat.
Cement for Cast-Iron In mixing cement for cast-iron, put 1 oz. of sal ammoniac to each hundredweight of borings, and use it without allowing it to heat. Multiply the length of any joint in ft. by the breadth in in., by the thickness in eighths, and by 3; the product will be the weight of dry borings, in lbs. avoirdupois, required to make cement to fill that joint nearly. Or, take of sal ammoniac, 2 oz.; flowers of sulphur, 1 oz.; clean cast-iron borings or filings, 16 oz.: mix them well in a mortar, and keep them dry. When required for use, take 1 part of this powder and 20 parts of clean iron borings or filings, mix thoroughly in a mortar, make the mixture into a stiff paste with a little water, and apply it between the joints, and screw them together. A little fine grindstone sand added improves the cement. A mixture of white paint with red lead, spread on canvas or woollen, and placed between the joints, is best adapted for joints that require to be often separated. In 100 lbs. of iron borings mix 1 oz. of flowers of sulphur, and add 1 oz. of sal ammoniac, dissolved in hot water. To Preserve for Use Pack it close in an iron vessel, and cover with water.
For Mending Iron Retorts Fifteen lbs. fire-clay, 1 lb. saleratus, with water sufficient to make a thick paste. This mixture must be applied to the broken part of the retort when the retort is at a good working heat; after this has been done, cover it with fine coal dust, and charge the retort for working.
Cement for Rock-work and Reservoirs Where a great quantity of cement is wanted for coarser uses, the coal-ash mortar (or Welsh tarras) is the cheapest and best, and will hold extremely well, not only where it is constantly kept wet or dry, but even where it is sometimes dry and at others wet; but where it is liable to be exposed to wet and frost, this cement should, at its being laid on, be suffered to dry thoroughly before any moisture has access to it; and, in that case, it will likewise be a great improvement to temper it with the blood of any beast.
The mortar must be formed of 1 part lime and 2 parts of well-sifted coal-ashes, and they must be thoroughly mixed by being beaten together, for on the perfect commixture of the ingredients the goodness of the composition depends.
To make Mortar Mortar is composed of quicklime and sand, reduced to a paste with water. The lime ought to be pure, completely free from carbonic acid, and in the state of a very fine powder; the sand should be free from clay, partly in the state of fine sand and partly in that of gravel; the water should be pure, and, if previously saturated with lime, so much the better. The best proportions are 3 parts of fine, and 4 parts of coarse sand, 1 part of quicklime, recently slaked, and as little water as possible. There should always be enough water added at first; if water is added after the slaking has begun, it will be chilled and the mortar lumpy The addition of burnt bones improves mortar by giving it tenacity and renders it less apt to crack in drying; but they ought never to exceed 1/4 of the lime employed.
When a little manganese is added to mortar, it acquires the important property of hardening under water; so that it may be employed in constructing those edifices which are constantly exposed to the action of water. Limestone is often combined with manganese; in that case it becomes brown by calcination.
Tunisian Cement This is composed of 3 parts of lime, 1 of sand and 2 of wood-ashes; these ingredients are mixed up with oil and water alternately, till they compose a paste of the desired consistency.
Water-cement, or Stucco Take 56 lbs. of pure coarse sand, 42 lbs. of pure fine sand; mix them together, and moisten them thoroughly with lime-water; to the wetted sand add 14 lbs. of pure freshburnt lime, and while beating them up together add, in successive portions, 14 lbs. of bone-ash. The quicker and more perfectly these materials are beaten together, and the sooner they are used, the better will be the cement; for some kinds of work it will be better to use fine sand alone, and for others coarse sand, remembering the finer the sand is the greater quantity of lime is to be employed.
To make a Fire and Water-proof Cement To 1/2 pt. of vinegar add the same quantity of milk; separate the curd, and mix the whey with the whites of 5 eggs; beat it well together, and sift into it a sufficient quantity of quicklime, to convert it to the consistency of a thick paste. Broken vessels mended with this cement never afterwards separate, for it resists the action of both fire and water.
I've seen stuff like this at Wikisource...did you pull it from Appropedia or something?
Jami McBride wrote: Beton Is superior, in every respect, to concrete. It is made in the same way, using hydraulic instead of common mortar.
Hm...not every respect.
Lime mortar is weaker, and a network of fine cracks will form if too much stress is applied, e.g. if a building settles slightly. If the concrete gets wet and dries again, "common mortar" from these recipes (no longer as common!) will fill in these cracks, and the structure will be as strong as before, in its new shape.
Hydraulic mortar (based on Portland cement) will not heal as large a crack, and compounding that problem, its strength will mean fewer, larger cracks. In general, structures can absorb a lot less damage over time when made with this recipe. It's a classic tradeoff, like the kind you see between a spring and a nail (wear safety glasses if you try to bend a spring!).
There are recent formulas with Portland cement and fibers of polyvinyl alcohol that combine higher strength with finer cracks and good ability to heal them, but they are currently experimental.
"the qualities of these bacteria, like the heat of the sun, electricity, or the qualities of metals, are part of the storehouse of knowledge of all men. They are manifestations of the laws of nature, free to all men and reserved exclusively to none." SCOTUS, Funk Bros. Seed Co. v. Kale Inoculant Co.
The chemical secrets of a concrete Roman breakwater that has spent the last 2,000 years submerged in the Mediterranean Sea have been uncovered by an international team of researchers led by Paulo Monteiro of the U.S. Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab), a professor of civil and environmental engineering at the University of California, Berkeley.
Analysis of samples provided by team member Marie Jackson pinpointed why the best Roman concrete was superior to most modern concrete in durability, why its manufacture was less environmentally damaging – and how these improvements could be adopted in the modern world.
"It's not that modern concrete isn't good – it's so good we use 19 billion tons of it a year," says Monteiro. "The problem is that manufacturing Portland cement accounts for seven percent of the carbon dioxide that industry puts into the air."
Portland cement is the source of the "glue" that holds most modern concrete together. But making it releases carbon from burning fuel, needed to heat a mix of limestone and clays to 1,450 degrees Celsius (2,642 degrees Fahrenheit) – and from the heated limestone (calcium carbonate) itself. Monteiro's team found that the Romans, by contrast, used much less lime and made it from limestone baked at 900˚ C (1,652˚ F) or lower, requiring far less fuel that Portland cement.
Cutting greenhouse gas emissions is one powerful incentive for finding a better way to provide the concrete the world needs; another is the need for stronger, longer-lasting buildings, bridges, and other structures.
"In the middle 20th century, concrete structures were designed to last 50 years, and a lot of them are on borrowed time," Monteiro says. "Now we design buildings to last 100 to 120 years." Yet Roman harbor installations have survived 2,000 years of chemical attack and wave action underwater.
How the Romans did it
The Romans made concrete by mixing lime and volcanic rock. For underwater structures, lime and volcanic ash were mixed to form mortar, and this mortar and volcanic tuff were packed into wooden forms. The seawater instantly triggered a hot chemical reaction. The lime was hydrated – incorporating water molecules into its structure – and reacted with the ash to cement the whole mixture together.
Roman seawater concrete holds the secret to cutting carbon emissions
Pozzuoli Bay lies at the northwestern corner of the Bay of Naples. The concrete sample examined at the Advanced Light Source by Berkeley researchers, BAI.06.03, is from the harbor of Baiae, one of many ancient underwater sites in the region. Black lines indicate caldera rims, and red areas are volcanic craters. Credit: Lawrence Berkeley National Laboratory
Descriptions of volcanic ash have survived from ancient times. First Vitruvius, an engineer for the Emperor Augustus, and later Pliny the Elder recorded that the best maritime concrete was made with ash from volcanic regions of the Gulf of Naples (Pliny died in the eruption of Mt. Vesuvius that buried Pompeii), especially from sites near today's seaside town of Pozzuoli. Ash with similar mineral characteristics, called pozzolan, is found in many parts of the world.
Using beamlines 220.127.116.11, 18.104.22.168, 12.2.2 and 12.3.2 at Berkeley Lab's Advanced Light Source (ALS), along with other experimental facilities at UC Berkeley, the King Abdullah University of Science and Technology in Saudi Arabia, and the BESSY synchrotron in Germany, Monteiro and his colleagues investigated maritime concrete from Pozzuoli Bay. They found that Roman concrete differs from the modern kind in several essential ways.
One is the kind of glue that binds the concrete's components together. In concrete made with Portland cement this is a compound of calcium, silicates, and hydrates (C-S-H). Roman concrete produces a significantly different compound, with added aluminum and less silicon. The resulting calcium-aluminum-silicate-hydrate (C-A-S-H) is an exceptionally stable binder.
At ALS beamlines 22.214.171.124 and 126.96.36.199, x-ray spectroscopy showed that the specific way the aluminum substitutes for silicon in the C-A-S-H may be the key to the cohesion and stability of the seawater concrete.
Another striking contribution of the Monteiro team concerns the hydration products in concrete. In theory, C-S-H in concrete made with Portland cement resembles a combination of naturally occurring layered minerals, called tobermorite and jennite. Unfortunately these ideal crystalline structures are nowhere to be found in conventional modern concrete.
Tobermorite does occur in the mortar of ancient seawater concrete, however. High-pressure x-ray diffraction experiments at ALS beamline 12.2.2 measured its mechanical properties and, for the first time, clarified the role of aluminum in its crystal lattice. Al-tobermorite (Al for aluminum) has a greater stiffness than poorly crystalline C-A-S-H and provides a model for concrete strength and durability in the future.
Finally, microscopic studies at ALS beamline 12.3.2 identified the other minerals in the Roman samples. Integration of the results from the various beamlines revealed the minerals' potential applications for high-performance concretes, including the encapsulation of hazardous wastes.
Lessons for the future
Environmentally friendly modern concretes already include volcanic ash or fly ash from coal-burning power plants as partial substitutes for Portland cement, with good results. These blended cements also produce C-A-S-H, but their long-term performance could not be determined until the Monteiro team analyzed Roman concrete.
Their analyses showed that the Roman recipe needed less than 10 percent lime by weight, made at two-thirds or less the temperature required by Portland cement. Lime reacting with aluminum-rich pozzolan ash and seawater formed highly stable C A-S-H and Al-tobermorite, insuring strength and longevity. Both the materials and the way the Romans used them hold lessons for the future.
"For us, pozzolan is important for its practical applications," says Monteiro. "It could replace 40 percent of the world's demand for Portland cement. And there are sources of pozzolan all over the world. Saudi Arabia doesn't have any fly ash, but it has mountains of pozzolan."
Stronger, longer-lasting modern concrete, made with less fuel and less release of carbon into the atmosphere, may be the legacy of a deeper understanding of how the Romans made their incomparable concrete.
Explore further: Experts propose research priorities for making concrete 'greener'
More information: "Material and elastic properties of Al-torbermotite in ancient Roman seawater concrete," by Marie D. Jackson, Juhyuk Moon, Emanuele Gotti, Rae Taylor, Abdul-Hamid Emwas, Cagla Meral, Peter Guttmann, Pierre Levitz, Hans-Rudolf Wenk, and Paulo J. M. Monteiro, appears in the Journal of the American Ceramic Society.
"Unlocking the secrets of Al-tobermorite in Roman seawater concrete," by Marie D. Jackson, Sejung Rosie Chae, Sean R. Mulcahy, Cagla Meral, Rae Taylor, Penghui Li, Abdul-Hamid Emwas, Juhyuk Moon, Seyoon Yoon, Gabriele Vola, Hans-Rudolf Wenk, and Paulo J. M. Monteiro, will appear in American Mineralogist.
Journal reference: Journal of the American Ceramic Society
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