permaculture

[Paul Wheaton <paul@richsoil.com>]

So all of the problems with it are in the manufacture, not in the use?  

We talked on this list a week or two ago about using ferro cement for a 
hobbit hole. 
I've since thought about similar uses for a root cellar.  Then about as a 
roofing
material for a hogan or cob dome.  

I remember once suggesting building a raised bed garden using mortared stone. 
 My father
talked me out of it:  "growies hate cement"   

I remember reading a book on ponds and docks and it saying that cement in the 
water was
the strongest solution, but also the worst for the environment.

I always figured it had to do with a really high pH.   Yes?  No?  More to it?

--- David Neeley <dbneeley@gmail.com> wrote:

> Production of Portland cement is environmentally somewhat of a
> disaster, in that massive amounts of air pollution result. In
> addition, it is a consumer of huge amounts of power--again with the
> resulting environmental problems.
> 
> Because it is heavy, transportation costs are likewise high--and
> contribute to the total embodied energy of the product.
> 
> Cement is used both in concrete and as an admixture in various other
> materials such as stucco or clay renders used on buildings.
> 
> Here is a brief description of the issue from the MIT Press:
> 
> "Hydraulic (chiefly portland) cement is the binding agent in concrete
> and mortar and thus a key component of a country's construction
> sector. Concrete is arguably the most abundant of all manufactured
> solid materials. Portland cement is made primarily from finely ground
> clinker, which itself is composed dominantly of hydraulically active
> calcium silicate minerals formed through high-temperature burning of
> limestone and other materials in a kiln. This process requires
> approximately 1.7 tons of raw materials per ton of clinker produced
> and yields about 1 ton of carbon dioxide (CO2) emissions, of which
> calcination of limestone and the combustion of fuels each contribute
> about half. The overall level of CO2 output makes the cement industry
> one of the top two manufacturing industry sources of greenhouse gases;
> however, in many countries, the cement industry's contribution is a
> small fraction of that from fossil fuel combustion by power plants and
> motor vehicles."
> 
> David
> 
> > 
> > I keep encountering situations where some cement would fix things right 
> > up.  But I
> seem
> > to recall that cement is bad for the environment.  Anybody know what 
> > problems cement
> causes?
> > 
> 
> > you know what I need clarification here. Cement is the bonding agent that
> > holds together the aggregates.
> > 
> > Concrete is the combination of aggregates and cement.
> > 
> > ???don
>