Talk:Types of concrete

Old concrete recipes

Added this:

Concrete has been used since ancient times. Regular Roman concrete for example was made from vulcanic ash (pozzolana), and hydrated lime. Roman concrete was superior from other concrete recipes (for example those consisting of only sand and lime. used used by other nations. Besides using vulcanic ash for making regular Roman concrete, brick dust can also be used. Besides regular Roman concrete, the Romans also invented waterproof concrete, which they made from vulcanic ash and clay.

Perhaps this can be improved, ie ratio's of the components isn't mentioned. I also don't know whether they used sand at all in the regular mix, or whether they (sometimes) used it, yet in tiny amounts. 91.182.46.186 (talk) 11:06, 10 September 2012 (UTC)

I think it's great that this article is getting some information, but the cite needs more specific information to be complete, like a timestamp of where these assertions are made within the video, director of the show, etc. See Template:Cite video and Citing TV or video recordings for guidelines on what to include. Thanks, Shearonink (talk) 05:47, 11 September 2012 (UTC)

In this article "regular Roman concrete" is specified as containing volcanic ash and hydrated lime, and "hydraulic concrete", volcanic ash and clay. However, the article for cement states "The chemical process for hydraulic cement found by ancient Romans used volcanic ash (activated aluminium silicates[citation needed]) with lime (calcium oxide)." So there seems to be in our dear Wikipedia some confusion about the Roman recipes. Lewis Goudy (talk) 19:59, 20 July 2016 (UTC)

Section on Geopolymer Contcrete

This is the original text:

Geopolymer concrete is a greener alternative to ordinary Portland cement made from inorganic aluminosilicate (Al-Si) polymer compounds that can utilise 100% recycled industrial waste (e.g. fly ash and slag) as the manufacturing inputs resulting in up to 80% lower carbon dioxide emissions. Greater chemical and thermal resistance, and better mechanical properties, are said to be achieved by the manufacturer at both atmospheric and extreme conditions.

Similar concretes have not only been used in Ancient Rome (see Roman concrete) as mentioned but also in the former Soviet Union in the 1950s and 1960s. Buildings in Ukraine are still standing after 45 years so that this kind of formulation has a sound track record.

I have removed the words "greener alternative" for a number of reasons, which include (i) A claim to be "greener" cannot be made without substantiation (ii) Indeed, the supporting documentation in terms of research into this subject area confirms that the "commonality" to all geopolymer cements is the treatment of the raw material with Sodium Hydroxide, in concentrations as high as 16M (i.e. ~64% NaOH) - at best, the claim to be "greener" is dubious without further substantiation.

Further issues:

PARA 1:

• Claiming a cement is an "alternative to Portland cement" is a very strong statement to make and cannot be supported without further embellishment.
• The mechanical properties are not substantiated in detail - what is meant by this? And what is meant by "better"?
• The sentence, "several additional plants coming online.... in 2008": this is promotional and in any event makes reference to 2008.

PARA 2:

• The source is dubious and is from a journalist rather than substantive research.
• In fact, to classify "Roman Cement" specifically as "Geopolymer cement" (or to even risk raising that innuendo) is not supported. For example, there is no evidence that the Romans used Sodium Hydroxide in cement preparation.

For this reason I have added the appropriate tags.

Jono2013 (talk) 12:37, 11 May 2013 (UTC)

COMMENTS on Roman Cement vs Geopolymer Cement: it is correct that the Roman did not use Sodium Hydroxide in cement preparation. On the opposite they induced the production of this alkali or of KOH, in situ, by an appropriate calcic activation with lime Ca(OH)2 of certain zeolitic volcanic tufs, such as phillipsite often found in Roman pozzolans. For a better understanding of the in situ reaction, please go to the section Roman Cement in Wikipedia article Geopolymer, from which I quote : From the digging of ancient Roman ruins, one knows that approximately 95% of the concretes and mortars constituting the Roman buildings consist of a very simple lime cement, which hardened slowly through the precipitating action of carbon dioxide CO2, from the atmosphere and formation of calcium silicate hydrate (CSH). This is a very weak to medium good material that was used essentially in the making of foundations and in buildings for the populace. But for the building of their "ouvrages d’art", especially works related to water storage (cisterns, aqueducts), the Roman architects did not hesitate to use more sophisticated and expensive ingredients. These outstanding Roman cements are based on the calcic activation of ceramic aggregates (in Latin testa, analogue to our modern metakaolin MK-750) and alkali rich volcanic tuffs (cretoni, zeolitic pozzolan), respectively with lime. MAS-NMR Spectroscopy investigations were carried out on these high-tech Roman cements dating to the 2nd. c. AD. They show their geopolymeric make-up. I agree with the general comments and issues outlined above and I have cleaned up the controversial journalistic statements. For this reason, I have removed the appropriate tags. Prof. Joseph Davidovits (talk) 09:31, 8 November 2013 (UTC)

Vacuum concrete

If vacuum concrete is something "being researched," how does that relate to this 1948 photo? Does the term have more than one meaning? If so, the meaning relevant to this photo should be covered, no? - Jmabel | Talk 01:11, 21 October 2014 (UTC)

What is C40/20 ?

Question moved here from top of the page. C40/20 means concrete specimen having cylindrical strength of 40 N/mm2 and 20 means the size of aggregate used in that mix. This is middle to high grade concrete used for parts experiencing loads such as slabs, foundations, columns, and footings. Strengths of concrete are typically given in twelve grades, such as C7.5, C10, C15, C20, C25, C30, C35, C40, C45, C50, C55, C60 and so on. DroneB (talk) 15:19, 13 December 2018 (UTC)

Conductive concrete

The main article Concrete mentions that carbon products have been added to make concrete electrically conductive, for deicing purposes. Will someone add this type of concrete to the article, noting that besides melting snow it can also provide efficient electrical grounding of equipment and shielding of electronics against EMP attack? See more information at:

• https://www.sciencealert.com/this-electrically-conductive-concrete-melts-snow-without-chemicals
• http://www.cubis-systems.com/uk/products/conductive-concrete/
• https://news.unl.edu/newsrooms/today/article/conductive-concrete-shields-electronics-from-emp-attack/
• https://www.engineeringcivil.com/electrically-conductive-concrete-properties-and-potential.html

DroneB (talk) 15:38, 13 December 2018 (UTC)

"Mix design" section very choppy

I'm an amateur wikipedian and know little about proper formatting, but it seems that the first section on "mix design" is very choppy, with each sentence blocked off as its own paragraph. It could be formatted into one paragraph with two trailing sentences without changing a single word, and could be modified into a single paragraph with minimal editing. — Preceding unsigned comment added by 67.254.145.190 (talk) 17:22, 20 March 2019 (UTC)