Cob: Re: cob walkways- use lime

[Michael Saunby]

On 02 November 1999 18:31, Don Stephens [SMTP:dsteph at tincan.tincan.org] 
wrote:
>
> What is meant by "earth" and "soil"?  <<G>> These are very unspecific
> terms - I'm used to dealing with catagories like "clay", "silt", "sand",
> "humus", etc., or mixes of these.
>

I guess for most people it means the earth on their doorstep, no point 
moving it from one place to another if you don't have to.  I expect most 
traditional building techniques are fairly insensitive to the actual makeup 
of the soil providing good judgement is applied to dimensions, quantities 
and additives. There's nothing much that can't be done with a few centuries 
of trial and error  (or months of rigorous science)

> ( ...I have a multi page report on what they did...
>
> Is there a way to access it?  I have a client couple building a
> demonstration ecohome to be open free to the public monthly or so and 
they
> will be wanting to show options for driveway, paths and floors.  Their
> weather-exposed answers so far have largely depended on some cement added
> to their 30/70 clay/sand onsite soil in about 1 to 4 or 5 mixes, but
> they'd be thrilled to show you could also forgo this energy-hogging,
> greenhouse-gas-producing product.

Hogging (or hoggin) is perhaps one answer.  A slightly arched (to give 
drainage to the sides) pathway of well compressed clay with fine gravel 
packed down hard.  Doesn't last forever, but is easily maintained, if you 
can spare a little labour to fill any holes/depressions that might happen 
from time to time and control weed that might grow if it's not used 
regularly.

>
> On the other hand, what eco-drawbacks are there to lime?  What escapes
> into the air during its mining, processing and hydrating? (and would one
> get even better results with hot lime?) Is it as energy-intensive as
> cement?  Where is it produced for use in various regions of the US, with
> how much transport energy consumption, typically?  And what harm, if any,
> is caused when it's used in on-earth applications like paths?  Does bad
> stuff leach down to harm plant roots and water tables?  Perhaps this has
> already been discussed on the lists, while I was off-line and up to my
> ears in design projects and overlooked it. If so, sorry, but perhaps a
> reitteration would be beneficial anyway, or reply off-list, if you wish.
> Thanx....Don

No idea where lime is produced in the US.  In the UK limestone is fairly 
common in many areas. It gives off carbon dioxide when "burnt" doesn't it? 
 Hardly a big problem I'd have thought.

Produce only what you need and use it only when you need it - 
sustainability is more about common sense than choice of materials.

Michael Saunby