A cement is a binder, a substance that sets and hardens independently, and can bind other materials together. The word "cement" traces to the Romans, who used the term opus caementicium to describe masonry resembling modern concrete that was made from crushed rock with burnt lime as binder. The volcanic ash and pulverized brick additives that were added to the burnt lime to obtain a hydraulic binder were later referred to as cementum, cimentum, cäment, and cemen
An early version of cement made with lime, sand, and gravel was used in Mesopotamia in the third millennium B.C. and later in Egypt. The vast system of Roman aqueducts also made extensive use of hydraulic cement.
The word concrete comes from the Latin word "concretus" (meaning compact or condensed), the perfect passive participle of "concrescere", from "con-" (together) and "crescere" (to grow).
Perhaps the earliest known occurrence of cement was twelve million years ago, when a natural deposit formed after an occurrence of oil shale naturally combusted while adjacent to a bed of limestone. These ancient deposits were investigated in the 1960s and 1970s.
On a human time-scale, lime mortars were used in Greece, Crete, and Cyprus in 800 BC. The Assyrian Jerwan Aqueduct (688 BC) made use of fully waterproof concrete. German archaeologist Heinrich Schliemann found concrete floors, which were made of lime and pebbles, in the royal palace of Tiryns, Greece, which dates roughly to 1400-1200 B.C. Concrete was used for construction in many ancient structures.
In the United States, 39 companies operate 118 cement plants in 38 states. Worldwide, the United States ranks third in cement production, behind China—the world’s leading producer—and India.
Aggregates that make up cement and concrete are taken from mines all around the world. Calcium is mostly found in deposits of limestone, marble, and chalk. Calcium is mined from the Earth's crust and is present in all parts of the world. Silicon is an abundant resource mined from sand. Since sand is abundant, easy to mine and fairly easy to process, it is the main ore source of silicon. The primary mining sources for aluminum, from the ore called bauxite, are in Ghana, Russia, Jamaica, Indonesia, and Surinam. Other areas where it is found, but not as much, are Australia, Brazil, Canada, and the United States. Iron is mined in many countries all over the world. The largest producer of iron is China, but it is also mined in the United States, Australia, Brazil, India, and many other countries.
The manufacture of cement and concrete occurs in many plants around the world and in the United States. The cement and concrete products and aggregates can travel great distances depending on the demand for specific mixes of the aggregates. Many of the aggregates are naturally occurring and very abundant.
History of Cement: http://www.cement.org/basics/concretebasics_history.asp
Virtual tour of cement making process: http://www.cement.org/basics/images/flashtour.html
Raw Materials: http://www.understanding-cement.com/raw-materials.html.
Faux Boise (False Wood)
Restoration of the original faux-bois ornamental trellises in The Huntingtonʼs Japanese Garden was done by Terence Eagan. http://www.fauxboisconcrete.info/
Concrete - Cement - Mortar
1. Portland cement is the basic ingredient of concrete. Concrete is formed with portland cement and creates a paste with water that binds with sand and rock to harden. Cement is manufactured through a closely controlled chemical combination of calcium, silicon, aluminum, iron and other ingredients. Common materials used to manufacture cement include limestone, shells, and chalk or marl combined with shale, clay, slate, blast furnace slag, silica sand, and iron ore. These ingredients, when heated at high temperatures form a rock-like substance that is ground into the fine powder that we commonly think of as cement. (http://www.cement.org/cement-concrete-basics/how-cement-is-made)
2. The cement industry is one of the primary producers of carbon dioxide, a major greenhouse gas. Concrete is used to create hard surfaces which contribute to surface runoff that may cause soil erosion, water pollution and flooding. The presence of some substances in concrete, including useful and unwanted additives, can cause health concerns due to toxicity and radioactivity. Wet concrete is highly alkaline and should always be handled with proper protective equipment. (http://en.wikipedia.org/wiki/Environmental_impact_of_concrete)
3.-Skin Contact – getting cement dust or wet concrete on your skin can cause burns, rashes, and skin irritations. Sometimes workers become allergic if they’ve had skin contact with cement over a long period of time.
-Eye Contact – getting concrete or cement dust in your eyes may cause immediate or delayed irritation of the eyes. Depending upon how much and for how long you get the dust in your eyes, effects to your eyes can range from redness to painful chemical burns.
-Inhalation – inhaling cement dust may occur when workers empty bags of cement to make concrete. When sanding, grinding, cutting, drilling or breaking up concrete, the dust generated has the same hazards as the dust from cement. Exposure to cement or concrete dust can cause nose and throat irritation. Long term exposure to concrete dust containing crystalline silica can lead to a disabling lung disease called silicosis. (https://www.statefundca.com/safety/safetymeeting/SafetyMeetingArticle.aspx?ArticleID=132)