cement?

If you are speaking of millenia, there are tens (hundreds?) of possible formulations of "cement" which were used since the "beginnings". Just look at puzzolane. Non long ago, dentist cements were even based on Zn phosphate or silicate. J.J.

Why don't you look up the manufacturing process. Solid state reactions take place that turn the raw materials into OPC.

Terry, Thanks for your suggestion. When I tried to use Google to search for the composition of cement or concrete, I just got companies that sell the stuff. But putting "cement manufacturing process" into Google did the trick. One site I found that had useful information was:

Here's some of what they say on the site: Cement is a hydraulic binder. That means it is a material which sets and hardens when mixed with water. Cement is primarily made up of limestone and clay. It is the result of chemical processing at very high temperatures, after several burning and grinding operations. The raw materials which go into the production of cement, primarily limestone and shale, are extracted from the quarry by blasting. They are then crushed and transported to the plant, where they are stored and homogenized. Very fine grinding provides a fine powder known as raw meal, which is then pre-heated and then enters the kiln. Flames reaching temperatures of 2000°C heat the material to 1500°C, before drastically cooling it by air blasts. The burning process produces cement clinker, the basic material required for the production of all cement. Clinker and gypsum are finely ground together to obtain a "pure cement". Secondary constituents are also added to make blended cements. Lastly, the finished products are stored in large silos from where they are dispatched in bulk or in bags to where they will be used.

On Tue, 16 Sep 2003 19:43:04 +0000 (UTC), "Terry Harper" wrote: