Talk:Cement

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Portland cement bias[edit]

This article with its recent changes is starting to concern me as it is developing a distinct bias towards Portland cement which already has an article of its own. Most of the recent additions, with regard to fuel, setting/hardening, environmental impact, are not about cement in general, and ignore other cements such as natural cements, calcium aluminate cements, magnesium oxychloride cements, phosphate cements, and others. Kpeyn 13:13, 24 August 2006 (UTC)

I've removed a bunch of Portland cement stuff recently. It's still missing information about other kinds of cements. Argyriou 19:31, 28 August 2006 (UTC)

In fairness, the term "cement" in common parlance almost always means a Portland-type product, and these products account for 95+% of world production. But I think details of manufacture etc need to be replaced with a refernce to the Portland article. Next job: to get the Portland article in shape.LinguisticDemographer 00:03, 28 September 2006 (UTC)

I think that Portland Cement should probably be folded into this article. I think that mention of other types of cement should be included on the periphery, with the main subject matter of the article being Portland Cement. This, given that the vast majority of cement produced in the world is portland cement. When people talk about "cement" in conversation it is overwhelmingly assumed that the person is referring to portland cement. -- Joetheguy 18:37, 13 November 2006 (UTC)

People mean Portland cement when they refer to just cement. It's the same with "car" meaning an automobile, even though trains and medieval wagons are also known as "cars". Notice the wikipedia entry of Car simply redirects you to Automobile. (bdiego) —Preceding unsigned comment added by 160.33.43.65 (talk) 19:19, 20 October 2009 (UTC)

There is some justification for this; for example, the French article combines all cements under one title. But this may just be because Portland is a bit too English for the French. Furthermore, the European standards just treat Portland as one of many possible "common" cements. On the other hand, US standards still maintain, to the point of neurosis, a rigid distinction between Portland and "blended" cements. I said above that 95% of world cements are "Portland-type", but a large proportion of those are "blended". Given that a "branched" structure is what we currently have, and one can easily click a link to get to the Portland article, and because disputes of this kind are making badly-needed refinement of the articles difficult, I am proposing exactly the opposite course of action, as mentioned in "Rationalization" below. . . LinguisticDemographer 22:15, 15 November 2006 (UTC)

Modifications 28 Sept 06[edit]

I have put in a bunch of extra stuff which I hope remedies some of the existing problems. I have yet to learn how to drop the font size in the math symbols - perhaps someone can show me how.LinguisticDemographer 23:55, 27 September 2006 (UTC)

Expansion details[edit]

Does anyone have any suggestions for specific items that are missing from this article, or can the expansion tag at the top of this page be removed? -- Beland 15:35, 16 October 2006 (UTC)

Information on non-portland cements. Argyriou 15:57, 16 October 2006 (UTC)

Not exclusively roman[edit]

We have example of hydraulic cement after the fall of Rome and before the advent of Portland cement. In Znachko-Iavorskii, I.L., New Methods for the Study and Contemporary Aspects of the History of Cementing Materials. Technology and Culture, Vol. 18, No. 1, 1977 the author describes a great deal of hydraulic lime mortar from all over the world before and after the fall of Rome, made from a startling variety of materials - things like egg whites, cheese and sour cream were used to achieve it. He has recipes from the high medieval period, and analysis of 11th century mortars that could set under water. These were not "weak pozzolans" - in many cases the different regional variations of hydraulic cement were superior to imported Portland cement in the 19th century.

Cement in the Americas the Mayas the Aztecs, and other Mesoamerican civilizations[edit]

This article does not mention cement use in the Americas by the Mayas the Aztecs, and other ancient Mesoamerican civilizations.

It was invented independently there, from what I heard by the Maya since the soil in the Maya region can turn into cement and then adopted by other neighboring peoples. I have seen cement work there myself at the ancient ruins in Mexico and Central America (Mesoamerica). I have seen that in other parts of the North and South America (the Inca ruins in South America, and the cultures located to the north of Mexico (now the United States and Canada) cement was not known in ancient times. I think it would be right to include at least a sentence or two about the use of cement in the region of Mesoamerican civilization, how it was invented and used independently in that part of the world, as well as some of the characteristics of that kind of of cement.

You know what to do. Cite it and write it! --Wtshymanski (talk) 15:44, 27 November 2011 (UTC)

Reactions[edit]

Can anyone tell me exactly what happens to the cement when it dries? All my textbook says is 'When water is added, a complex series of reactions occur which make it set'. Nonagonal Spider 06:30, 24 October 2006 (UTC)

The answer for Portland cement is explained fairly thoroughly. Argyriou 07:21, 24 October 2006 (UTC)

Rationalisation[edit]

There was a reversion (22:08 5 Nov 06) of a fairly sensible edit, which prompted me to have another look at the article as a whole. It's problematic because the term "cement" has a very wide scope of specialised use, although in normal parlance in most languages it means just one thing. The current structure discourages effective editing. There may be a standard wiki-approach to this problem, but it's a closed book to me so I offer the following re-arrangement suggestions for discussion.

  • change current disambiguation statement to read "For uses other than Construction Cements, see Cement (disambiguation)".
  • accordingly, remove "Geology" section, which disrupts the logical flow of the article.
  • organise the remaining article into main sections (1) hydraulic, (2) non-hydraulic (of which we currently have few examples)
  • In the hydraulic section, start with a definition of hydraulicity, which will absorb the current "Setting and Hardening" section.
  • Follow this with "History of Hydraulic Cements". Under this title, it is now sensible to mention early cements in time sequence, pointing out how hydraulicity was achieved in each case, and elaborate as knowledge allows.
  • Then follows "Modern Hydraulic Cements", which breaks out into categories as in current sections 4.1-4.3. As far as possible, refer discussion of "pure" Portland to the Portland article.

I'd also like to remove the reference to US usage of the term "Hydraulic cement" from the preamble, because reference to ASTM Specification C 1157 and terminology C 219 shows that US usage is in line with usage elsewhere. Currently it's very confusing.

The above will I think free-up the considerable expansion of the article that is still necessary. The above is fairly radical surgery, and I'd like to get a few nods of agreement before proceeding......LinguisticDemographer 21:04, 9 November 2006 (UTC)

Sounds good, though I'd make an article of the geology section rather than just deleting it. I'd also suggest adding Portland cement to the disambig page. Argyriou (talk) 23:09, 9 November 2006 (UTC)

I have placed a draft of the article amended as proposed above in User:LinguisticDemographer/Draft, resisting the urge to be bold and put it straight in, since tempers seem to be a bit frayed at the moment. Hopefully, it covers (with citation) the current war over "what the Romans put in their concrete". I took out most of the reference to fuels, since it seems to me that specialised Portland-based processes do not belong in this article, and they are indeed covered in Portland cement and cement kiln, though perhaps not in a way satisfactory to all opinions. Anyway, I'd like some feedback. . .LinguisticDemographer 19:46, 15 November 2006 (UTC)

There being no comment, and no recent edits compromising the suggested text, I have implemented the above LinguisticDemographer 12:11, 9 December 2006 (UTC)

Trade[edit]

As threatened in the portland article a month ago, I have moved the section on trade from there to here, because it refers to all cements and not specifically Portland. . . .LinguisticDemographer 15:18, 27 May 2007 (UTC)

cement[edit]

why is it not adviceable to keep cement expossed to air? —Preceding unsigned comment added by 81.199.17.19 (talk) 09:30, 4 March 2008 (UTC)

Should not?[edit]

  • Cement should not be confused with concrete as the term cement explicitly refers to the dry powder substance.

Isn't shouldn't an inherently POV word? Why can Wikipedia decide (without a cite, mind you) that I "should" use one word over another? If it had a cite, I'd fix it, but, without one, I don't know how to do it without using weasel words. — trlkly 04:35, 20 November 2008 (UTC)

Nope. 'Tis correct as shown. POV implies a difference of opinion is possible. Here, we're trying to be clear as to the terms. Cement and concrete are often conflated incorrectly. It's not POV to correct that. Cheers, MARussellPESE (talk) 05:59, 21 November 2008 (UTC)
Conflated incorrectly? Who gets to decide what is correct, especially when by your own admission your proscription contradicts the actual manner in which this word is often used by native speakers of this language? Cesiumfrog (talk) 00:56, 23 November 2008 (UTC)
How about - "In common use, the word 'cement' is often used to refer to concrete, but the current dictionary definition restricts it to the dry powder or the hydrated paste that acts as a binder and hardener for concretes and grouts"? This is based on the Wiktionary definition - http://en.wiktionary.org/wiki/cement (which could also do with some editing!). --Muchado (talk) 08:50, 20 February 2009 (UTC)

Marketing?[edit]

"companies like Binani Cement Ltd are on a full expansion mode" - umm... this sounds like marketing to me, and the whole section on Indian production seems out of tone with the rest of the article. I don't think the section needs to be removed, but it needs references and needs to be rewritten to remove marketing information such as this. If references are not provided then it all needs to be removed. --Muchado (talk) 08:50, 20 February 2009 (UTC)

The entire "EMC Cement" section rings deafeningly of marketing, with sweeping claims lacking technical detail ("The resultant concretes can have the same, if not improved, physical characteristics as "normal" concretes — at a fraction of the Portland cement") and entire paragraphs whose tone and absence of content combine to evoke nothing so much as the airs of a promotional pamphlet: "Put simply, EMC Activation is a patented, cost– and energy–efficient, near zero-emission technology for the high replacement of Portland cement in concrete."

We are never told exactly what EMC Activation entails or how works. We are only, in addition to being repeatedly informed that it is patented, told that it "generates high-energy particle impacts", whatever that means.

I would vote for the removal, barring its radical overhaul, of the entire "EMC Cement" section. EMC Cement has every right to do its own marketing, but not on Wikipedia's dime, or Wikipedian readers' time. Steeljack (talk) 22:57, 8 April 2013 (UTC)

Random note from top of page[edit]

CEMENT

THE PRODUCT are bhai ye sab galat hai Cement is a chemical compound existing of limestone or chalk, clay, sand and gypsum to form the final product we know as cement. Limestone or chalk, clay and sand are burned at a temperature of about 1400 degrees Celcius in a rotary kiln or oven to create a product called clinker. The clinker is milled together with about 5% gypsum in ball mills to a fine powder, the final product.

USAGES OF CEMENT Cement is used in various applications such as a substance to build brick houses (to bind the bricks together), in a mixture with sand and stone it is used as concrete for the foundation of a house or the walls of larges buildings or to build bridges or heavy construction work.

CONTRIBUTES TO THE ENVIRONMENT Cement manufacturers are striving to produce an environmental friendly product by incorporating power saving strategies and alternative fuel resources into the process.

Visit the British Cement Trade Association website www.bca.org.uk for more info

An environmental section is not fundamentality required for a user's understanding of the nature of cement. Although the data on carbon dioxide emissions is intriguing, it is not necessarily the truth and needed to demonstrate the uses of cement.


Note: regarding the info on main page; gypsum plaster and ordinary lime are NOT hydraulic cements as they do not form insoluble hydrates during curing; they will not set underwater; and if set and then placed underwater, will dissolve. Any decent basic source will reflect this e.g. Taylor, Cement Chemistry; Illston, Construction Materials; Neville, Concrete Technology etc etc.

--Tom (talk) 14:17, 7 October 2009 (UTC)

Definitions of "hydraulic" and "non-hydraulic"[edit]

The terms "hydraulic and "non-hydraulic" were used in the lead without providing definitions there or anywhere else in the article. The adjective "hydraulic" is then applied extensively in the rest of the article (hydraulic cement, hydraulic renders, hydraulic mortars, hydraulic lime, etc.). What these terms actually mean may be crystal clear to someone who has worked in the construction industry, but the lack of clear definitions is not especially helpful to the layman, who may not have a technical background. Short definitions have been added in an attempt to make these qualifiers comprehensible to a broader public. Piperh (talk) 10:20, 22 May 2010 (UTC)

Global Warming Bias[edit]

There is a section that promotes a biased opinion on the Global Warming theory. This presents anthropomorphic global warming as fact rather than a disputed theory. Please clear political theory out of this scientifc article. —Preceding unsigned comment added by 86.154.246.46 (talk) 10:44, 12 June 2010 (UTC)

Environmentalism and the Anthropormorphic Climate Change Theory[edit]

Though anthropomorphic Climate Change is becoming increasingly discredited as a theory, environmentalists continue to accuse cement manufacturing of contributing to greenhouse gas emissions both directly through the production of carbon dioxide when calcium carbonate is heated, producing lime and carbon dioxide.

This change and the above mentioned (non-signed comment) are unfortunately far from being neutral and clearly expresses a biased point of view: please: remain neutral and factual. Shinkolobwe (talk) 11:27, 13 June 2010 (UTC)

CO2 emissions[edit]

Cement manufacturing releases CO2 in the atmosphere both directly when calcium carbonate is heated, producing lime and carbon dioxide,[1] and also indirectly through the use of energy, particularly if the energy is sourced from fossil fuels. The cement industry produces about 5% of global man-made CO2 emissions, of which 50% is from the chemical process, and 40% from burning fuel.[2] The amount of CO2 emitted by the cement industry is nearly 900 kg of CO2 for every 1000 kg of cement produced. [3]

This is verifiable. Shinkolobwe (talk) 11:46, 13 June 2010 (UTC)
Researchers at the German Karlsruhe Institute for Technology (Karlsruher Institut für Technologie) have developed a process which reduces carbonates (380 kg as compared to 1200 kg for ton of clinker), increases silicates (to 690 kg, compared to 100 kg), and manages to halve both the carbon dioxide produced and the energy required to make the clinker. The initial mixture only requires an autoclave at 200°C. The process has been patented and the first plant to produce this "Celitement" is in the works. The trick is some sort of intermediate hydrate, but since I am neither a chemist nor an engineer, I am reluctant to try to describe this process in the main article. There is more information here in English and a press release in German.

Janko (talk) —Preceding undated comment added 09:36, 6 August 2010 (UTC).

Hello Janko,
Many thanks for this very interesting information.
If I correctly understand the information provided on the website of Celitement, indeed, everything is based on an intermediate hydrate: celite.
According to the information mentioned here, after hydration, celite forms CSH without producing portlandite (Ca(OH)2). It means, it is also a low pH cement. Usually, low pH concrete requires addition of pozzolanic materials to the mix of cement and aggregate to transform portlandite into CSH.
In contrast, the absence of portlandite and the resulting "low pH" would no longer protect the carbon steel rebars from corrosion.
In the coming weeks, I will try to develop the question of this innovative cementitious materials with low-CO2 emission. Since several months, I was rather disappointed by commercially-driven green cement papers, often without strong scientific and technical basis. But this information seems me also to be a technical and scientific breaktrough which deserves more attention. Kind regards, Shinkolobwe (talk) 14:45, 24 August 2010 (UTC)

Numbers don't make sense[edit]

From article:


In 2010, the world production of hydraulic cement was 3,300 million [billion surely] tonnes. The top three producers were China with 1,800 ... In 2006, it was estimated that China manufactured 1.235 billion tonnes of cement ... "Demand for cement in China is expected to advance 5.4% annually and exceed 1 billion tonnes in 2008 [lower than 2006 figure above by circa 20%!!] ... The amount of CO2 emitted by the cement industry is nearly 900 kg of CO2 for every 1000 kg of cement produced. [so cement CO2e world should = about 3 billion tonnes or maybe 8% of world CO2e --way too high and Chinese CO2e for cement 2006 over a billion but

"Chinese economy has created such a demand for building materials that cement production there last year [2006] released 540m tonnes of carbon dioxide" http://www.guardian.co.uk/environment/2007/oct/12/climatechange — Preceding unsigned comment added by 172.218.243.160 (talk) 02:25, 23 September 2012 (UTC)

Environmental segregation and union[edit]

The article on Environmental impact of concrete repeats a lot of the content in this article, in the section on cement and environmental impact. I propose that that article be changed to Environmental impact of cement and concrete and that the substance of the matching section of the cement article be moved out and suitably united with the new article, together with any other material in other articles that match. I'd be willing to help if desired. Any comments? JonRichfield (talk) 12:12, 15 March 2013 (UTC)

Sintering???[edit]

A lot of this article requires clarification. I have little knowledge of cement, but the term sintering does sound familiar in its connection; however, what I understand by sintering matches more or less the text in the article on sintering. It is not what I understand to happen in a cement kiln, though I readily accept that I might misunderstand the process. Can anyone tell me whether there is genuine sintering going on in the kiln, and if so in which form?

Secondly, I really do think that if I find that passage confusing, that I might not be the only one; is anyone in a mood to elaborate the text for the benefit of the ignorant? JonRichfield (talk) 06:36, 2 April 2013 (UTC)

OK, I since have found much of the answer to the first part of my question in the article Clinker (cement). However, my request that someone should do a bit of clarification still stands. JonRichfield (talk) 07:38, 2 April 2013 (UTC)

Chemistry[edit]

I have added more information about the chemistry ruling the action of hydraulic and non-hydraulic cements. All comments welcome. --Silvio1973 (talk) 11:08, 17 June 2013 (UTC)

Split into subsections/paragraphs[edit]

I think this section "Portland cement blends" and this section "Non-Portland hydraulic cements" should each be broken into subsections for each of the different types of cement rather than being single very long paragraphs. -- Dougher (talk) 17:31, 14 October 2013 (UTC)
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