Hey Starship not only do you have me reading 'things I don't want to read about' but also looking for more! How are you on types of cement? Two reasons, first I found this quote below in Wikipedia and noticed the mention of "low-energy" cements would you elucidate?

Calcium sulfoaluminate cements are made from clinkers that include ye’elimite (Ca4(AlO2)6SO4 or C4A3\bar \mathrm{S} in Cement chemist’s notation) as a primary phase. They are used in expansive cements, in ultra-high early strength cements, and in "low-energy" *cements.

Second reason is that years ago I used a black cement in a bit of sculpture, I was told at the time that it wasn't Portland and no colourants were added. I have no idea what it was but it was great stuff, does this poor description ring any bell? Have asked at various local cement purveyors to be only met with a concrete and stony silence.

*my bold

Building with (steel-reinforced) concrete is one of the most silly things, mankind ever invented. If you have insight into the static of concrete constructions, e.g.

• the complex problems that are created simply by neglecting natures laws and to replace them with technological vanity by complicating structures needlesly,
• the contradictory solutions to otherwise relatively simple static rules, beforehand the very dangerous phenomenon of punching of columns and walls, which does not exist in traditional constructions (arches and vaults),
• the dangers of misunderstanding the sometimes very difficult task of resolving the equilibrium of forces in each part of the structure (which exist also elsewhere, but is much much much more pronounced in concrete),
• the fact, that concrete does not hold together, even without external forces, but has to be bound together by steel reinforcement,
• that concrete has to break before it works,
• that water will enter these cracks an the steel will rust, that concrete, therefore, is not durable, but has to be replaced every 50 years,
• that concrete weights 2,5 metric tonnes per m3 (a ceiling of 20cm is 5,0 kN/m2!!! (=500kg/m2) This is incredible, even the highest density for ramped earth is not more than 2,2 to/m3)
• that concrete structures are, therefore, very heavy, and everything, that wears them, has to be also very heavy and overdimensioned
• that this is completely needles, because mankind knows better alternatives since we began to exit Africa some million years ago!!

and if you consider further

• the fact, that concrete is much too dense to allow respiration of the structure, that it is very unhealthy to live in concrete houses, that it ruins your conjunctive tissues and empoisons
  you with all kinds of spores of fungus that grow in airtight environment,
• that the high density makes concrete a very good conductor and leads to - hurray to the industry - a special layer of insulation,
• that the calcareaous nature of cement in concrete reacts with the moister of human skin (and others, too) and that, therefore, working with concrete is a torture,
• that the steel in the structure compromises the electric impulses, living beings work with and that it is, therefore, recommended to build barns for cattle without reinforced ceilings (for the cattle!!!) because they otherwise give less milk or meat or whatever,
• cement production is some 8-10% (dont nail me on this, but it is something about this numbers) of worldwide CO2-production,
• that finally concrete was, is, and will always be, just UGLY
  

, if you take all this and you think about the fact that the worlds biggest concrete manufacturer, the swiss Holcim group, which is responsible for the devastation of vast natural mountains and ecosystems, the polution of air and water, won for the third time in a row the title "Leader of the Industry" of Dow Jones Sustainable Index, that civil engineers don't even learn of alternatives in the university, just concrete, steel and wood, if they have luck (but wood is already a scarce ressource and no alternative, once the energy lacks), and not even hear about the fantastic possibilities of mud and adobe,

and if you take all the other reasons and examples, than you can only hope that Peak Oil is also Peak Concrete!

P.S. I decided to write a book it, because no one knows about all this, everone takes concrete for granted and "natural". This is a very important peak-oil-issue!

Yours Snomm

Right.

Because they like the quality of our clinker compared to the African clinker (another reason which I didn't elaborate on is that of cement type, which is combination of chemical make up and burn temperature). Most cement is "Type I." Type II has a slightly different chemical makeup and is "burned" at a much higher temperature (harder on the kiln refractory, particularly at the end of a production campaign when the kiln will be rebricked).

A good basic site for info is:
http://www.cement.org/basics/

Well, any increase in cost in materials will ultimately be reflected in the final cost of construction. Steel prices have soared over the past few years and are as much of a contributor to increased cost as anything else.

The minimum energy requirement per ton (or Mg) of clinker is the amount required to dry the materials, calcine the carbonate to oxide (CaCO₃ to CaO) and the amount to raise the temperature of the calcined mixture to the reaction temperature of the mixure of calcium, silica, alumina, and iron (that reaction is exothermic). Beyond that, it's the type of cement process and to some extent the type of cement that dictates the overall energy requirement. The most energy efficient is the precalciner/short kiln and the least is wet kiln.

But as I think I pointed out in a previous post, the choice between wet and dry is usually the largest energy difference. But that choice is governed by conditions of the raw materials and to some extent the chemistry.

The only raw material limitation I see on the horizon is the energy source (gas or coal). Limestone probably isn't a problem (though the contamination with MgCO₃ and other single valence alkalies must also be limited), and sand, clay (sources of alumina and silica) and iron oxide won't be problems.

It's not necessarily a simple issue balancing these cross-cutting interests. There is a facility that I've evaluated that has relatively high energy requirements because it's a wet-process kiln and it has a relatively high alkali content (potassium) feed material but it provides not only cement but, because of it's design, potash as an agricultural supplement.