Check the data. Lime is not a panacea for the atmosphere.
Lime production puts more Carbon Dioxide into the atmosphere PER
POUND OF PRODUCT than cement production does. The clay component in
cement clinker doesn't carbonize as much as straight limestone. When
cement is mixed with flyash the differences per pound of product
become even more pronounced.
The cement industry overall puts more carbon dioxide in the
atmosphere because far more cement is manufactured. Cement is simply
used more. The more that lime replaces cement the more carbon
dioxide is put in the atmosphere.
If cement is a big Ford SUV on the highway, lime is a HUMMER as far
as carbon dioxide is concerned. Hummers are more polluting per
vehicle, but there are less of them on the road, so Ford SUV's put
out more total pollution.
Yes, lime reabsorbs some co2 back from the atmosphere, but it doesn't
reclaim nearly as much as is released during its manufacure. Cement
also reabsorbs a little, but very very slowly compared to lime. Does
this mean that cement lasts longer? Does this mean that less energy
gets used due to repairs/reconstruction over time? How often do
walls get replastered? How often does a concrete foundation get
redone? Perhaps that's not the ideal example, but you get my point.
Quoting the Department of Energy:
...
The lime production industry is the second largest producer of
process-related CO2 emissions. In a process similar to cement clinker
production, limestone is heated in a kiln to drive off the carbon to
create lime. While there are energy efficiency improvements that
could be undertaken in the lime production process, lime production
inherently produces carbon dioxide. In 2005, the lime production
industry's process-related CO2 emissions were 15.7 million metric
tons of CO2, second only to the cement industry.
...
The above quote was snipped from:
http://www.eia.doe.gov/oiaf/servicerpt/csia/special_topics.html
I'm not anti-lime. I LIKE lime (both the citrus and the calcium
types). It has many wonderful uses. Great stuff.
Lime has different properties from cement. Each material has its
place.
IMHO the argument about which is greener is pointless. Each material
can be used in a responsible manner. Each material can be used in a
irresponsible manner.
Build a super efficient house and you'll be way ahead no matter what
you use.
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