Talk:Portland cement

message: The first picture in the article shows 'CEM II/B-M' cement, which is strictly speaking not Portland cement, but Portland-composite-cement (EN 197-1) and has a clinker content <79%. This might be confusing because the picture is placed beside the statement that Portland cement has more than 90% clinker. However, the name 'Portland cement' is sometimes used for Ordinary Portland cement only or for all cements with some Portland cement content, including blended cements/composite cements.
CEM I is Portland cement with >90% clinker (so called 'Ordinary Portland cement' in the USA).   —Preceding unsigned comment added by 129.132.211.56 (talk) 15:24, 9 June 2010 (UTC)
thread_title:  picture shows Portland-composite cement, not (Ordinary) Portland cement 

message: I believe this article lacks neutrality and requires some restructuring.   The disputed second paragraph in the article reads as follows:
"Manufacture of portland cement requires the burning of large quantities of fuel, typically coal or natural gas, which along with impurities contained in the limestone can result in significant emissions of pollutants regulated in many countries, including greenhouse gases such as nitrogen oxides (NOx) and sulfur dioxide, as well as particulates (PM 10, PM 2.5), volatile organic compounds (VOCs), and carbon monoxide. Cement plants emit substantial quantities of arsenic, lead and mercury."
This paragraph initiates a discussion of pollution at the outset of the article, which is pejorative and atypical of other wikipedia articles dealing with global industries (see: Petroleum and Steel, for examples).   The paragraph is factually incorrect, listing oxides of nitrogen and sulfur dioxide as greenhouse gases; they are not.  The final sentence declares that "cement plants emit substantial quantities of arsenic, lead and mercury" which is not supported by fact.   See the discussion of cement chemistry later in the article and note that none of these elements play any part in the manufacturing process, nor are such heavy metals typical of the limestone and shale that comprise the essential raw materials in production. 
The disputed third paragraph under "Safety and health" is similarly pejorative.   It reads:
"Living near a portland cement plant can have serious health consequences due to the large quantity of pollutants released by the manufacturing process, as well as fugitive emissions from related on-site activities (such as haul roads, blasting, and truck traffic). The pollutants released by portland cement industry are known to contribute to lung and circulatory problems, including asthma, bronchitis, and heart attacks, as well as cancers. Hovever, many residents in these communities consider these risks to be acceptable in view of the economic benefits. For instance, polls show the residents of Ste. Genevieve County, Missouri to be overwhelmingly in favor of the cement plant being built there beginning in 2005. This plant will be the largest cement plant in the United States."
The statement "living near a portland cement plant can have serious health consequences" is an allegation lacking any source, certainly not a statement from NPOV.  Looking to the article on Oil refineries as an example,  public  health concerns voiced by environmental groups should be cited as such, with appropriate links.  The environmental concerns must be cast as topics of public debate with the article taking a strictly neutral position.     
Following the example of the articles on Petroleum and Steel, I propose to retitle the "Safety and health"  heading as "Safety and Environmental Effects" and relocate the discussion of fuel usage, impurities, and pollution under that heading.    I have collected some data on typical cement plant emissions to place as a data table under that heading, but for the sake of balance some examples of emissions control technology as applied to cement production might be appropriate as well.
I invite informed, objective debate on these issues…please speak here before deleting or reverting.  Thanks JJackson8 20:02, 2 November 2005 (UTC)
replies: text: Cool by me!!  If there are other parts of the article you want to have a go at, there's plenty of scope for improvement. . . .LinguisticDemographer 14:56, 6 September 2007 (UTC)
thread_title:  [[NPOV]] lacking in this article 

message: Shouldn't the raw material be calcium carbonate (44%) not calcium oxide (44%) ?
Portland clinker (at least in N europe) consists of 45-65% (% by weight) Tricalcium silicate C3S. The finished product (cement) consist of 62-67% calcium oxide. Oyvind 09:52, 27 October 2005 (UTC)
thread_title:  possible mistake? 

message: "...The high energy requirements and the release of significant amounts of carbon dioxide makes cement production a concern for global warming...."   
This is an opinion - the author's - and is inappropriate in this context.
Agreed. Delete it. Gtoomey 02:47, 3 November 2005 (UTC)
thread_title:  Global warming? 

message: Under "Types of Portland Cement" the comment "Note: Type II cement is not really used any more in industry." appears under the heading for Type IV.  Is it out of place, or should it be referring to Type IV?
Eitherway, type II cement is used almost exclusively in Northern California. And if the comment is referring to Type II it is a definite mistake.
In the US, rather more than half Portland cement consumption is Type II.  On the other hand, no Type IV has been made in the last 30 years or so, because low heat concrete is normally now made with Type II and a large addition of ground granulated blastfurnace slag (ggbs).LinguisticDemographer 15:33, 27 September 2006 (UTC)
thread_title:  Possible mistake? 

message: #ASTM C150 and EN 197 are the two major standards for Portland Cement - ASMT used in America+ and EN used in Europe+. Both are definitly notable ;) and just covering one of them is a one-sided and "protectionistic".
#As there are more than one standard the composition of cement and clinker differs - there is a larger span for the composition. To give the composition with aproximate 44% etc is to "coarse" as the spread is larger than can be coverded by the word "Aproximate"
#As to emmisions - lets settle that on this page and try to stay avay from an revert-war between different POV's. Keep it clean and simple, pleace.
Oyvind 09:41, 2 November 2005 (UTC)
thread_title:  Regarding composition, Standards and emision 

message: This section was obviously written by a shill for the cement industry.  Cement is one of the most energy intensive products in the world, and manufacturers are seeking out any means of reducing their energy costs.  The practice of incinerating hazardous and nonhazardous waste is extremely controversial.  For example, one Lafarge plant at St. Constant in Quebec, Canada is producing stratospheric (and increasing) amounts of dioxins as a result of incinerating scrap tires.
All I'm saying is that this particular section is far from neutral.  It reads like propaganda from the cement industry.
I agree - there is on-going opposition to the use of wastes in cement kilns, which were not designed for the job, and much data which suggests that they are not as good at burning everything up with no emmissions than is suggested by the industry.  In addition, cement companies are not properly set up for the collection and storage of such wastes, and this introduces further complication.  Even burning normal fuels, such as coal, results in dangerous emmissions of mercury, and of green-house gases.JaneH 13:00, 5 July 2006 (UTC)
thread_title:  Cement plants as alternatives to conventional waste disposal or processing 

message: The section on the history of Portland cement duplicates thatin the "Portland cement" article, but has a different emphasis, giving greater credit to the Aspdins. Ideally the general history should be in the cement article, and the complicated evolution of modern Portland cement in the more specialised article.
I missed an explanation of how cement sets at the microscopic level.
=== very confusing usage ===
Wait, so portland cement was invented by a guy who didn't invent portland cement?
I think what the article is trying to say is that the cement originally named "portland cement" is not the stuff which is today called "portland cement" (sort of like the concept that tinfoil is actually aluminum and pencil leads are made of graphite)  but I'm not entirely sure. Someone who knows should fix here, and in the Aspdin article... -- Akb4 05:20, 31 August 2006 (UTC)
thread_title:  History of cement 

message: Wait, so portland cement was invented by a guy who didn't invent portland cement?
I think what the article is trying to say is that the cement originally named "portland cement" is not the stuff which is today called "portland cement" (sort of like the concept that tinfoil is actually aluminum and pencil leads are made of graphite)  but I'm not entirely sure. Someone who knows should fix here, and in the Aspdin article... -- Akb4 05:20, 31 August 2006 (UTC)
thread_title:  very confusing usage 

message: CO2 production - people keep saying that 1 unit of CO2 is produced for every unit of PC (in the chemical reaction).   Do they mean "about 1 unit"? Rich Farmbrough, 17:43 20  September 2006 (GMT).
I have pasted my initial respose to this into the Environmental section, since it appears to read OK.LinguisticDemographer 17:38, 30 September 2006 (UTC)
thread_title:  CO<sub>2</sub> 

message: In the introduction, it is stated that the wet process is no longer used, and that as a consequence clay is no longer used, because (among other reasons) it contributes too much alumina.  This is all incorrect. (1) The wet process, although much less used, is still in operation.  Wet and semi-wet process still accounts for more than 10% of UK production.  In the US it's still around 20%.  In some countries it's 100%.  (2) Clay usage is not restricted to wet process: many dry process plants use clays.  (3) Clays are in no way chemically distinct from shales; high-alumina shale are just as common as high-alumina clays.LinguisticDemographer 16:28, 27 September 2006 (UTC)
replies: text: Please feel free to make the appropriate edits, particularly if you have references for your assertions. See WP:BOLD Argyriou 16:42, 27 September 2006 (UTC)
thread_title:  Introduction: Use of Clay 

message: This section appears to be based on texts written 50 or more years ago.  The typical composition data is out of date.  There was a survey of North American portland cements in the mid 1990s (Gebhardt, R. F., "Survey of North American Portland Cements: 1994," Cement, Concrete, and Aggregates, December 1995, 145-189).  The following mean compositions come from this:
Type I: 55% (C3S), 18% (C2S), 8% (C3A), 9% (C4AF), 2.0% MgO, 2.8% (SO3), 1.3% Ignition loss, and 1.0% free CaO.
Type II: 54% (C3S), 20% (C2S), 6% (C3A), 11% (C4AF), 2.2% MgO, 2.7% (SO3), 1.2% Ignition loss, and 1.0% free CaO.
Type III: 55% (C3S), 17% (C2S), 9% (C3A), 8% (C4AF), 2.2% MgO, 3.5% (SO3), 1.3% Ignition loss, and 1.3% free CaO.
Type V: 55% (C3S), 20% (C2S), 4% (C3A), 13% (C4AF), 2.5% MgO, 2.3% (SO3), 1.0% Ignition loss, and 0.8% free CaO.
The description of Type III states that it is made by raising the C3S and C3A in the mix.  This was the practice in the 1930s, but nowadays, very few manufacturers deliberately make a different mix for Type III, and this fact is born out by the above data - Type III is typically almost identical to Type I in chemistry.  Type III is differentiated from Type I by finer grinding: typical Blaine fineness (m2/kg):
Type I: 377
Type II: 374
Type III: 547
Type V: 370
Although not specified in this way in ASTM standards, Type III is bought and sold on the basis of its 1-day strength (or even 16-hour strength), which is proportional to the fineness and the C3S.  Clearly, the modern 50% boost in early strength given by Type III can't be achieved by tweaking C3S content.  Main uses are in pre-cast concrete and in pre-stressed units, where fast mould turn-around is called for.  The usage text given fails to address this and appears to describe the situation 50 years ago.  In general Type III can not be used in contact with ground waters!!
The whole section really needs a re-write from scratch.LinguisticDemographer 16:55, 27 September 2006 (UTC)
thread_title:  Description of ASTM C 150 Cements 

message: I deleted the section on Plastic Cement, because it is not a Portland cement, since it contains components that are prohibited in the Portland specification.  It is covered under cement, although the item might need a little expansion.LinguisticDemographer 16:57, 29 September 2006 (UTC)
thread_title:  Plastic Cement 

message: I have a problem with the existing text which implies that setting is due to calcium aluminate hydration.  This really isn't true.  C3A causes flash-set if not controlled by sulfate addition.  Addition of sulfate causes formation of a very limited initial amount of ettringite, which forms an insoluble crust over the C3A surfaces and prevents further hydration.  The normal set occurs as a result of initial hydration of C3S.  Pure C3S, in fact, sets in a manner similar to well-controlled Portland cement, after a delay of an hour or two.  The ettringite layer passivating the C3A subsequently redissolves quite slowly to form Afm after the C3S-based set is well established.  LinguisticDemographer 00:31, 9 October 2006 (UTC)
replies: text: May I suggest that you edit the article along the lines you propose above? Adding references and/or footnotes would be welcome, also. For guidelines, please see WP:RS and WP:FN. In particular, citation of a standard textbook would be very helpful to our readers. Best wishes, Walter Siegmund (talk) 02:44, 9 October 2006 (UTC)
thread_title:  Setting Mechanism 

message: I have changed the order of the article to give (I hope) a more logical read.  I have also eliminated one or two redundancies (see "Setting mechanism" above), and have added a bunch of text which I think is probably valuable.  This also seeds two new articles: rawmill and cement mill.  I'm on the lookout for good photos for these.  The wiki server was playing up as I pasted this, and there may be a few typos, errors etc.  Please fix if you get to it before I do.
LinguisticDemographer 17:56, 11 February 2007 (UTC)
thread_title: Reorganized 11 Feb 2007

message: I changed a section that seems to be based on a very old text, in order to reflect modern usage.  There are many repeated and circular wikilinks: I have taken out some of these.  Is there some sort of "bot" that does this automatically? . . .LinguisticDemographer 15:08, 18 March 2007 (UTC)
thread_title: Edits 18 March 2007

message: The current section 4 needs to be relocated to the "Cement" article.  The text refers explicitly to "hydraulic cement", on which the world production is based.  A large proportion of this is strictly non-Portland, as is the large majority of the Chinese production.  I'll move it if there are no objections. . . .LinguisticDemographer 19:04, 24 April 2007 (UTC)
thread_title: Portland cement business

message: Are the cement components namely C3S, C2S, etc. are known as Bogue's Compounds? —Preceding unsigned comment added by Rohit.k88 (talk • contribs) 10:10, 26 May 2007
The notional compounds C3S, C2S, C3A and C4AF are informally referred to as "Bogue compounds", and the process of calculating their amounts is referred to as "Bogue analysis", because this calculation was first proposed by Bogue.  The actual minerals present in Portland cement clinker (alite, belite, tricalcium aluminate and calcium aluminoferrite) differ substantially from the notional Bogue compounds in composition, so that the calculated Bogue compound composition is often very different from the true mineral composition.  For this reason, and because direct methods of mineralogical analysis are now available, "Bogue analysis" is now gradually going out of favor. . . .LinguisticDemographer 11:02, 27 May 2007 (UTC)
thread_title:  Bogue's Compounds 

message: "Rawmix" does not seem to be the usual term.  Relevant sources show that the normal term is 'raw mix'.  Likewise for "rawmill"/'raw mill', etc..
Here are a couple of examples:
*  — official industry site calls it "raw mix"
*  — UN document uses "raw mix" almost exclusively throughout, except for a singe instance (which might be a misprint).
— DIV (128.250.204.118 08:26, 22 June 2007 (UTC)
thread_title:  "Rawmix" → 'raw mix' ''etc.''

message: When I go to the hardware store to buy cement, I've been told to ask for something called 'premix'.   In what way is 'premix' different from 'rawmix'?  I'm not an expert on this sort of thing, and I thought I'd go to Wikipedia to get an answer on the matter.  216.99.198.63 (talk) 23:31, 10 August 2008 (UTC)
replies: text: Premix is cement mixed with sand or sand and gravel: it's really mortar or concrete in a "just add water" form – useful if you only need a little.  Rawmix is a stage in the manufacture of cement, so it's not at all the same thing – it's like the difference between wheat and cake-mix.  By the way (and I don't in the least mean to sound unfriendly) WP isn't really meant to be a Q&A site – try one like www.answerbank.com.  Richard New Forest (talk) 14:08, 11 August 2008 (UTC)
thread_title:  Premix isn't the same thing as rawmix 

message: Substantial parts of this article were written by me.  I am a well known researcher in this field.  I hereby assert that all those parts of the article that were written by me and are not provided with references are the results of my own original research.  Wikipedia rules state that information that is the result of original research is prohibited, and where such information is unambiguously present in an article, it is the duty of every editor to remove it forthwith.
LinguisticDemographer (talk) 21:56, 15 April 2010 (UTC)
thread_title: Original Research

message: The article talks about 'rawmix' or 'raw mixture', but not 'raw meal'.  In both wet, semi-wet and dry process kiln systems the terms 'rawmix'(raw mix) or 'raw mixture' invariably refer to the heterogeneous mixture of the unground raw materials which are fed to the raw mill. However, the homogenous powdered material which comes out of the raw mill in a dry process kiln (or the dried powdered slurry in a semi-wet process) is generally referred to as 'raw meal'.  For clarity, I suggest that this convention also be observed in the article. Ted Krapkat (Cement Australia) 203.161.131.164 (talk) 01:17, 27 July 2010 (UTC)
thread_title:  Rawmix or rawmeal (raw meal)? 

message: In the Safety section, it says:
:As of 2010, however, the development of formulations of cement that include fast-reacting pozzolans such as silica fume as well as some slow-reacting products such as fly ash have allowed for the production of comparatively low-alkalinity cements (pH<11)[6] that are much less toxic and which have become widely commercially available, largely replacing high-pH formulations in much of the United States. Once any cement hydrates, the hardened mass loses chemical reactivity and can be safely touched without gloves.
*Low-alkalinity cements have been available since before 2010. I've changed that.
*There needs to be a citation for low-alkalinity formulations "largely replacing high-pH formulations in much of the United States."
*The loss of chemical reactivity occurs after the cement sets, not hydrates. I've fixed that.
Argyriou (talk) 00:54, 6 October 2010 (UTC)
thread_title:  Safety 

message: I understand that the curing process of Portland cement generates heat, and that for very large castings, measures must be taken to prevent heat damage. Perhaps this is worth mentioning in the article.  — Preceding unsigned comment added by Mohanchous (talk • contribs) 16:18, 6 March 2011 (UTC)
thread_title:  Heat During Curing 

message: The article has a link to flux_(metallurgy), which is confusing. I had hoped to correct the link, but the Flux_(disambiguation) page did not enlighten me either. Some more explanation would be useful.Brinerustle (talk) 11:05, 25 April 2011 (UTC)
thread_title:  Flux ?

message: There is a problem with this article: certain sections have been marked as "unreferenced" for two years, during which time no attempt has been made to supply references.  The author of these sections freely admits that they are Original Research.  Original Research is absolutely prohibited in Wikipedia.  Accordingly I have deleted them.  Do not restore them - you are absolutely forbidden by Wikipedia rules to restore them - unless you also supply valid references from a reliable - i.e. peer reviewed - source.  — Preceding unsigned comment added by 193.61.220.13 (talk) 11:55, 24 November 2011 (UTC)
thread_title:  Unreferenced and original research 

message: "Typical electrical energy consumption is of the order of 90-150 kWh per tonne cement, equivalent to 0.09-0.15 kg CO2 per kg finished cement if the electricity is coal-generated."
This is FLAT wrong and out by an order of 1000!!!!!!!!!!
See, table at page 4 of http://www.wbcsdcement.org/pdf/CSI%20GNR%20Report%20final%2018%206%2009.pdf
Jono2013 (talk) 16:36, 4 April 2013 (UTC)
replies: text: Jono2013, the reference you cite, p 14, declares that about 5000 megajoules of energy are used per tonne of clinker. Does clinker mean cement? There are 3.6 MJ per kilowatt hour, so 5000 MJ is about 1400 KwHr. But why quote KwHr? Energy quoted in MJ makes sense because fossil fuel and combustible waste are used for heating the kiln. When electric power is mentioned, does this mean that cement kilns are electrically heated? DavidJErskine (talk) 06:22, 7 March 2014 (UTC)
thread_title:  Energy Requirements 

message: The linked entry under the EMC section is tagged for deletion, for apparently good reason. This product most definitely doesn't belong on the Portland cement entry page.  — Preceding unsigned comment added by 98.26.94.209 (talk) 06:35, 4 May 2013 (UTC)
thread_title:  EMC Section reads like an advertisement and is not representative of Portland cement. 

message: ASTM itself identifies its standards with no space between the letter and numbers (for example, ASTM C150).  Even the page ASTM International identifies a page without the superfluous space.  I realise that it is fairly common usage to insert a space.  But the space contributes nothing to readability or clarity.  I think that the nomenclature by which an organisation identifies its own standards should prevail.
EN apparently identifies its standards with a space.  So EN 197-1 is the canonical form.  "EN197" and "EN-197" are not in proper form.  Whatever the organisation's preferred form is, that is what we should use.  75.210.43.64 (talk) 03:26, 1 July 2013 (UTC)
thread_title:  ASTM and EN standards naming convention 

message: Can it really still be true that the most important property of one of the central and widespread materials of 20th and 21st century civilisation, tightly and widely formulated, and composed only of inorganic molecules, is still, more than 150 years after its formulation, only partly understood?
That's what it used to say in my chemistry books when I was growing up in the 60s. The books were probably repeating what was known in the 30s. That's the 1930s. If this statement is true, what use the scientific century? Atconsul (talk) 10:18, 2 September 2013 (UTC)
thread_title:  Complex Series of Chemical Reactions Still Only Partly Understood 

message: I understand many people have their own political views and ambitions but they don't belong in these articles since all they do is derail the entire page from the intro. I get it that some people think we all need to hear about carbon this and carbon that but they shouldn't be wrecking these articles by pushing a political agenda. Someone needs to just create large articles about the "Environmental Effects of.." and put a link to it. Making a page called "Environmental Effects of Road Construction" is more appropriate than complaining about how building roads is evil for the environment in every single article related to it.
Another thing too: this bias isn't just honest inquiry either. There's a clear pattern of abuse on these pages where anything that in any way, shape, or form that benefits rural and suburban America is inundated with massive amounts of environmental criticism. I can't even read an article about roads without hearing someone's diatribe about how they think everyone should be forced to live in big cities due to mother nature.
Either make separate pages about the environmental connections to various subjects or, if no one wants to give up their political grandstanding, then just clear out those sections altogether. When I can't even find any information on the comparison between asphalt and regular concrete roads or the history of asphalt usage but I can find detailed criticism of the asphalt/concrete industry, then things need to change.75.167.216.168 (talk) 06:40, 11 May 2015 (UTC)
replies: text: I totally agree. Most of the CO2 produced from rocks is returned back into building materials to form carbonates. The only contribution into atmosphere is by burning hydrocarbons... which may be recaptured and used for other industries. AXONOV (talk) ⚑ 20:02, 4 August 2022 (UTC)
replies: text: Extensive, often repetitive, and weakly sourced commentary about environmental impact, etc often damage articles. Some of that material is valuable, but often it is garbage, hearsay, WP:UNDUE, WP:OR, or just preaching. My guess is that editors who introduce such content are incapable to contribute core information, but they fervently want to contribute somehow.  Warnings are easy to post. Its our job as editors to weed out that content when it is inferior (as well as our jobs to enhance such content when appropriate).--Smokefoot (talk) 21:49, 4 August 2022 (UTC)
thread_title:  Environmental Effects Sections Are Ruining Articles  

message: Do mention some uses in dentistry. Jidanni (talk) 16:33, 20 April 2022 (UTC)
thread_title:  Dentistry