Cement

__ The Invention of Cement __ By: Jocelyn

__What__ (What is Cement?)

Cement is a very hard kind of rock which [|people] make themselves. People all over Asia and North Africa used cement as a mortar to stick bricks together, or to make a hard floor, from the Stone Age onward, for instance in the [|Great Wall of China] (about 200 [|BC]). But concrete was not used as a building material until the [|Roman Empire]. You start with [|lime] and powdered [|clay], and you add [|water]. You mix it all up, and it turns into this soft squishy stuff, a lot like gray Playdough. Then you make it into whatever shape you want, or pour it into a mold, and let it dry. When it is dry it will be hard (like Playdough) and even if you get it wet it won't get soft again. If you want a stronger building material, you can add sand or gravel, and that makes [|concrete].
 * Kidipede**

In the most general sense of the word, a **cement** is a binder, a substance that sets and hardens independently, and can bind other materials together.
 * Wikipedia**

Cements are finely ground powders that harden when mixed with water. Cement has been in use since about 200 B.C. The cement used by ancient Egyptians was made of calcium carbonate and gypsum. Both the ancient Greeks and Romans used a cement made of calcium carbonate and limestone.
 * enotes**

__Who__ (Who used it?)

The Assyrians and Babylonians used clay as the bonding substance or cement. The Egyptians used lime and gypsum cement. In 1756, British engineer, John Smeaton made the first modern concrete (hydraulic cement) by adding pebbles as a coarse aggregate and mixing powered brick into the cement. In 1824, English inventor, Joseph Aspdin invented Portland Cement, which has remained the dominant cement used in concrete production. Joseph Aspdin created the first true artificial cement by burning ground limestone and clay together. The burning process changed the chemical properties of the materials and Joseph Aspdin created a stronger cement than what using plain crushed limestone would produce. **Answerbag**

The Romans developed a concrete (a mixture of cement, sand, and some other finely crushed rock) that could be used to construct underwater drains and bridges. The concrete was embedded in a lime putty, mixed with brick dust or volcanic ash.**enotes** Roman cement" is a substance 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 a "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]. **Wikipedia**

__Where__ (Where was it discovered?) It is uncertain where it was first discovered that a combination of [|hydrated non-hydraulic lime] and a [|pozzolan] produces a hydraulic mixture (see also: [|Pozzolanic reaction]), but concrete made from such mixtures was first used on a large scale by [|Roman engineers].[|[][|1][|]] They used both natural pozzolans ([|trass] or [|pumice]) and artificial pozzolans (ground brick or pottery) in these concretes. Many excellent examples of structures made from these concretes are still standing, notably the huge [|monolithic] [|dome] of the [|Pantheon] in [|Rome] and the massive [|Baths of Caracalla].[|[][|2][|]] The vast system of [|Roman aqueducts] also made extensive use of hydraulic cement.[|[][|3][|]] The use of structural concrete disappeared in medieval Europe, although weak pozzolanic concretes continued to be used as a core fill in stone walls and columns.
 * Wikipedia**

__When__ (When was it discovered?) Cement has been in use since about 200 B.C. The cement used by ancient Egyptians was made of calcium carbonate and gypsum. Both the ancient Greeks and Romans used a cement made of calcium carbonate and limestone.
 * enotes**

Cement is a very hard kind of rock which [|people] make themselves. People all over Asia and North Africa used cement as a mortar to stick bricks together, or to make a hard floor, from the Stone Age onward, for instance in the [|Great Wall of China] (about 200 [|BC])
 * Kidipede**

__Dates__

Cement has been used since about 200 BC.

Around 60AD the Roman Empire used cement and concrete as a main building material.

In 1756, John Smeaton made the first modern concrete.

In the 1780s James Parker developed Roman Cement.

In 1817, James Frost made artificial cement by burning chalk and clay.

In 1824, Joseph Aspdin created Portland cement

In 1845 Issac Johnson made the first modern Portland Cement by firing a mixture of chalk and clay at very high temperatures.

In 1848 William Aspdin made an improved version of Portland Cement and called it Patent Portland Cement even when he had no patent.

In 1850 onwards, the use of concrete in construction grew rapidly.

In the early 1930's it was soon discovered that Portland cement while it had a faster setting time, was not a durable.

__Photos__ http://www.google.com/imgres?imgurl=http://www.hardwarestore.com/media/product/221101_front200.jpg&imgrefurl=http://paint-and-supplies.hardwarestore.com/50-276-concrete-patch.aspx&usg=__ravy2_yK6hKNFtK03s-fnQAcg64=&h=200&w=200&sz=28&hl=en&start=0&zoom=1&tbnid=f_I-wonw3rkXeM:&tbnh=128&tbnw=126&prev=/images%3Fq%3Dportland%2Bcement%26hl%3Den%26biw%3D1280%26bih%3D560%26gbv%3D2%26tbs%3Disch:10%2C209&itbs=1&iact=hc&vpx=704&vpy=183&dur=68&hovh=160&hovw=160&tx=154&ty=93&ei=u8AiTZTvH5GWcaG8yN4F&oei=u8AiTZTvH5GWcaG8yN4F&esq=1&page=1&ndsp=20&ved=1t:429,r:17,s:0&biw=1280&bih=560__//

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//http://www.google.com/imgres?imgurl=http://mightygodking.com/images/cement.gif&imgrefurl=http://mightygodking.com/index.php/2008/09/03/its-only-a-matter-of-will-part-two-concrete/&usg=__ixpXtFHwie7NQJea-R2xADxMZ_Y=&h=402&w=600&sz=187&hl=en&start=0&zoom=1&tbnid=CA178x5A5JKILM:&tbnh=121&tbnw=171&prev=/images%3Fq%3Dcement%26hl%3Den%26biw%3D1280%26bih%3D560%26gbv%3D2%26tbs%3Disch:1&itbs=1&iact=hc&vpx=239&vpy=112&dur=3171&hovh=184&hovw=274&tx=144&ty=77&ei=aon4TJrtIJGWcb7Ykb0D&oei=aon4TJrtIJGWcb7Ykb0D&esq=1&page=1&ndsp=21&ved=1t:429,r:1,s:0__

__http://www.google.com/imgres?imgurl=http://www.lughertexture.com/images/rsgallery/original/concrete%2520cement%25201.JPG&imgrefurl=http://www.lughertexture.com/index.php%3Foption%3Dcom_rsgallery2%26page%3Dinline%26id%3D278%26Itemid%3D6&usg=__QxCU-clpdKsvBxenABqxT806Wmc=&h=1500&w=2000&sz=781&hl=en&start=39&zoom=1&tbnid=xcB_h2wkp8xwrM:&tbnh=128&tbnw=179&prev=/images%3Fq%3Dcement%26hl%3Den%26biw%3D1280%26bih%3D560%26gbv%3D2%26tbs%3Disch:10%2C1031&itbs=1&iact=hc&vpx=651&vpy=237&dur=1240&hovh=194&hovw=259&tx=144&ty=137&ei=poz4TJbfGobMuAOn07yBAw&oei=aon4TJrtIJGWcb7Ykb0D&esq=5&page=3&ndsp=18&ved=1t:429,r:15,s:39&biw=1280&bih=560



Webliography

[] [] http://en.wikipedia.org/wiki/Cement http://www.enotes.com/science-fact-finder/general-science-technology/when-was-cement-first-used http://en.wikipedia.org/wiki/Roman_cement http://en.wikipedia.org/wiki/Portland_cement http://www.understanding-cement.com/history.html

This is the rubric I got for the wiki: