Homestead mailing list

[Clansgian AT wmconnect.com]

> >Of course if you overdo it and make it too thin it
> will not be strong enough, but if you put the least
> amount of water possible it won't fill the voids. 
> This application would not require the strength of
> something like a loading dock

THe old saw that drier is stronger and wetter is weaker is over simplistic.  
Too dry is far weaker than too wet because the unoxidized dust does not get 
distributed around the aggregate well enough.

Mortar or condrete that is rather wet will be weaker initially, but a 
mysterious thing about concrete is that it becomes stronger with time.  
Initially the 
CaO (and other similar molecules) combine with water to make Ca(HO)2.  As the 
water is driven off and replaced by carbon dioxide CaC03 is formed.  The 
exact amount of water means that the exchange of H2O for CO2 is quicker and 
the 
concrete sets harder quicker.

What gives concrete its strength, however, is that the calcium atoms will 
randomly begin to share bonds.  This continues for hundreds of years so the 
properly made concrete or mortar continues to harden for years.

Adding extra lime (CaO) to the portland is done to make the mix easier to 
work and stick to the work surfaces.  It weakens the concrete.  The amount of 
lime that is in concrete is the right amount already.   If you don't need 
rock 
hard mortar joints, then adding lime to 'fluff' up the mixture does not  harm.

The foundation of my house is made of laid stone.  A sort of permanent slip 
form of 4" block was laid straight for the inside wall, stones laid 12" thick 
outside that.  The space in between the stones and block was poured full of 
concrete, and as has been suggested here, it was mixed thin so that it would 
fill 
the form completely.

Understanding what hardens concrete in the long run, I used limestone sand 
rather than silica sand.  THe paces where this mix filled between stones, I'm 
not saying you can't break it, but you' better bring a lunch and plan on 
staying 
all day.

A mason was visiting when I was doing the masonry of the house.  Along the 
concrete footing were bits of conventional mortar I had used building some 
inconsequential parts of walls and bits of the above described mix.  He 
picked up 
one of the mason's hammers and was idly chipping up the bits of mortar while 
were talking until he came to none of the bits made of limestone sand.  He 
hit 
it and the hammer jarred in his hand, the bit or mortar didn't move.  He hit 
it 
harder and then harder.  A tiny bit chipped off but the rest stayed firmly 
fixed.  "Damn,  " he says, "What the hell is that stuff??"

Just look beyong the dry-good, wet-bad saw to how concrete works.   </HTML>