[Cob] Re: Wet cob and forms

[ocean]

We've mixed cob in a small gas-powered cement mixer.  First using a 1/2 
drill with a large drywall mud-beater, we whipped the clay into a wet 
slip.  We added added the slip to sand in the mixer, letting the mixer 
turn until uniformly coating sand with clay.  This is a wet slurry of 
sand and clay, to which we added dry straw, mixing until the straw was 
uniformly covered.  The straw absorbed some of the excess water, making 
a wet cob, which couldn't be built up more than 8" or so per day.

But I've often wondered if we'd mixed several batches at once, then 
dumped them all in a pile and let it sit a few days.  The excess water 
would drain out and the cob might then be a better building/sculpting 
consistency.

On Jun 22, 2006, at 12:43 PM, Lance Collins wrote:

> David T asked
>
>> >Anyone ever used forms to hold a layer of cob on the wall?
>>
>> It's called 'poured earth' or ' formwork cob' or several other names.
>>
>> How does it compare to straight cob?
>
> pro: mix quality is less critical,  so can do wetter mix in a concrete 
> mixer
>
> con: need to have formwork
>      : takes time to set up forms
>      : forms are usually straight so wall shape is less flexible
>      : wall is not one big mud brick so less strong
>
> Overall using forms is quicker with less work but less flexible (in 
> design) and not as strong.
>
> As in earth building generally the characteristics of your soil are 
> important in deciding whether to cob, use forms, go strawbale or make 
> blocks for an adobe wall.  And there are lots of variations on block 
> making.
>
> Lance
> (in Aus)
>
>
> -- 
> No virus found in this outgoing message.
> Checked by AVG Anti-Virus.
> Version: 7.1.394 / Virus Database: 268.9.2/373 - Release Date: 
> 22/06/2006
>
>
>
> _______________________________________________
> Coblist mailing list
> Coblist at deatech.com
> http://www.deatech.com/mailman/listinfo/coblist
>