| |
 |
|
|
Science Forum Index » Materials Forum » cement?
Page 1 of 1
|
| Author |
Message |
| Bruce Ritchings |
 Posted: Tue Sep 16, 2003 12:27 am |
|
|
|
Guest
|
Clearly, I was asking the wrong question when I queried what concrete
is, because from your descriptions, it's just cement with some rocks
(sand/gravel) thrown in for good measure. I guess the real question I
should have asked was: what is cement, and more specifically how it's
formulation has changed over the millenia. Clearly lime is involved,
but agricultural lime (Calcium Carbonate) is pretty darn unreactive,
so there must be a more reactive form of lime (quick lime?) which is
involved. The next question is how exactly this lime reacts with the
material it's put with to create something hard and durable. I hope
this doesn't turn into a chemistry question, but materials science is
certainly based in part on the chemical properties of the materials we
use. Anyway, if anyone has useful information on cement, I'd love to
hear it. Thanks. Bruce |
|
|
| Back to top |
|
| jacques jedwab |
| Posted: Tue Sep 16, 2003 6:52 am |
|
|
|
Guest
|
In article <o0bdmv0mc4j9tdvif784ppcb9sqrvgop71@4ax.com>, Bruce Ritchings
<britchings@hotmail.com> wrote:
Quote: Clearly, I was asking the wrong question when I queried what concrete
is, because from your descriptions, it's just cement with some rocks
(sand/gravel) thrown in for good measure. I guess the real question I
should have asked was: what is cement, and more specifically how it's
formulation has changed over the millenia. Clearly lime is involved,
but agricultural lime (Calcium Carbonate) is pretty darn unreactive,
so there must be a more reactive form of lime (quick lime?) which is
involved. The next question is how exactly this lime reacts with the
material it's put with to create something hard and durable. I hope
this doesn't turn into a chemistry question, but materials science is
certainly based in part on the chemical properties of the materials we
use. Anyway, if anyone has useful information on cement, I'd love to
hear it. Thanks. Bruce
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. |
|
|
| Back to top |
|
| Terry Harper |
| Posted: Tue Sep 16, 2003 9:43 am |
|
|
|
Guest
|
"Bruce Ritchings" <britchings@hotmail.com> wrote in message
news:o0bdmv0mc4j9tdvif784ppcb9sqrvgop71@4ax.com...
Quote: Clearly, I was asking the wrong question when I queried what concrete
is, because from your descriptions, it's just cement with some rocks
(sand/gravel) thrown in for good measure. I guess the real question I
should have asked was: what is cement, and more specifically how it's
formulation has changed over the millenia. Clearly lime is involved,
but agricultural lime (Calcium Carbonate) is pretty darn unreactive,
so there must be a more reactive form of lime (quick lime?) which is
involved. The next question is how exactly this lime reacts with the
material it's put with to create something hard and durable. I hope
this doesn't turn into a chemistry question, but materials science is
certainly based in part on the chemical properties of the materials we
use. Anyway, if anyone has useful information on cement, I'd love to
hear it. Thanks. Bruce
Why don't you look up the manufacturing process. Solid state reactions take
place that turn the raw materials into OPC.
--
Terry Harper
http://www.terry.harper.btinternet.co.uk/ |
|
|
| Back to top |
|
| Uncle Al |
| Posted: Tue Sep 16, 2003 12:10 pm |
|
|
|
Guest
|
Bruce Ritchings wrote:
Quote:
Clearly, I was asking the wrong question when I queried what concrete
is, because from your descriptions, it's just cement with some rocks
(sand/gravel) thrown in for good measure. I guess the real question I
should have asked was: what is cement, and more specifically how it's
formulation has changed over the millenia. Clearly lime is involved,
but agricultural lime (Calcium Carbonate) is pretty darn unreactive,
so there must be a more reactive form of lime (quick lime?) which is
involved. The next question is how exactly this lime reacts with the
material it's put with to create something hard and durable. I hope
this doesn't turn into a chemistry question, but materials science is
certainly based in part on the chemical properties of the materials we
use. Anyway, if anyone has useful information on cement, I'd love to
hear it. Thanks. Bruce
(Don't confuse cement and mortar) Cement is silaceous rock and
limestone burned together in a kiln and the clinker thereform ground
fine. If you want to do better than that you need an old fart
engineer.
Concrete is cement plus filler (sand to aggregate to big rocks). The
chemistries of cements is hellishly complex. Whenever something
important is built the poured concrete is always continuously
sampled. It is the only way to know. If you haven't talked with your
Teamster representative, watch out for sugar.
If you take finely divided cement, and a water-soluble polymer, blend
with water under vacuum and cast without voids, you can make credible
cement springs. Water destroys them. Take a newly cured concrete
whatever, saturate it with supercritical CO2 in a pressure chamber.
You get rapid 50-year full cure. This is generally inapplicable to
buildings and roads.
Google
cement chemistry 121,000 hits
concrete chemistry 340,000 hits
mortar chemistry 34,400 hits
--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
"Quis custodiet ipsos custodes?" The Net! |
|
|
| Back to top |
|
| Bruce Ritchings |
| Posted: Tue Sep 16, 2003 2:39 pm |
|
|
|
Guest
|
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:
http://www.lafarge.com/cgi-bin/lafcom/jsp/content.do?function=ce_process&lang=en
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"
<Terry.Harper@btinternet.com> wrote:
Quote: "Bruce Ritchings" <britchings@hotmail.com> wrote in message
news:o0bdmv0mc4j9tdvif784ppcb9sqrvgop71@4ax.com...
Clearly, I was asking the wrong question when I queried what concrete
is, because from your descriptions, it's just cement with some rocks
(sand/gravel) thrown in for good measure. I guess the real question I
should have asked was: what is cement, and more specifically how it's
formulation has changed over the millenia. Clearly lime is involved,
but agricultural lime (Calcium Carbonate) is pretty darn unreactive,
so there must be a more reactive form of lime (quick lime?) which is
involved. The next question is how exactly this lime reacts with the
material it's put with to create something hard and durable. I hope
this doesn't turn into a chemistry question, but materials science is
certainly based in part on the chemical properties of the materials we
use. Anyway, if anyone has useful information on cement, I'd love to
hear it. Thanks. Bruce
Why don't you look up the manufacturing process. Solid state reactions take
place that turn the raw materials into OPC. |
|
|
| Back to top |
|
| |
|
Page 1 of 1
All times are GMT - 5 Hours
The time now is Sat Sep 06, 2008 5:32 pm
|
|