Replies

1. 
   Piffin | Sep 14, 2005 03:25am | #1

   Best done above freezing, but there are techniques.

   my masons set up for a winter job by placing a water barrel and then piling the sand around it. They have an electrode heating element in the water to keep it warm, and residual heat keeps the sand thawed also. Then the whole thing is kept covered with a concrete curring balnket. After each day's work, a blanket is also placed over it to help it cure before it freezes,

   In Colorado, I saww masons doing stone work down to zero temps with siomilar methods. They worked with a tent plastic over their area and a hater, aand insulated the work at night. They used a section of steel pipe laid on the ground and dumped the sand over it, then ran a torpedo heater through the pipe to keep warm sand.

   Your bond cracks - several possibnilities. Could be you are mixing the mud too wet, or adding water after it starts to kick. Could be freezing materials. Most likely, you are not misting your product, so the dry cultured stone sucks the moisture right out of the mix and leaves you with poowder between the stone and the mud.

    

    

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1. 
   Asr | Sep 17, 2005 03:18pm | #4

   Thank you for your imput. Do you add anti-freeze to it. We added a special type of mix last year and it seemed to work.

1. 
   Piffin | Sep 17, 2005 06:04pm | #5

   I've heard of adding anitfreeze, but never done it or seen it done. With concreete, enough heaat is generated by the reactions to keep it good with minimal insulation while iot cures, but the small amt of mortar vs the larger mass of the stone, artificial or otherwise, makes it imperative that the materials be kept above freezing, in my thinking. Antifreeze may prevent the crystaline structure of ice from harming the mix, but it does nothing to help the curing process take place. If yiou add enough antifreeze to keep ice out at, say 0°, the mortar is still uncured. Your goal is to get the finished product to be sound enough to last a few generations, not just long enough to get paid. That means keeping the mass above freezing during the first critical three days 

    

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1. 
   Asr | Sep 17, 2005 07:51pm | #6

   Do you know where I can get the facts to back up what you are saying concerning this statement so I can show it to my supervisor.

1. 
   Piffin | Sep 17, 2005 08:53pm | #7

   Any book that teaches the basics of using portland products will explain it. The written instructions on labels of any premixed portland product will state it clearly. "Avoid Freezing until cured" or something to that effect. to understand this better, look at the physaics of water and how it behaves. and of portland cement and the hydraulic reaction that makes it harden over time.Water added to the mix of portland cement and the aggregate( sand) goes into a chemical reaction called hydration, I believe. The water becomes part of the final product. This is why we say that it cures, and not that it drys. If it werrer to dry before it cured, the mix would fall apart - why scaling happens on the surface of some concrete slabs when they are poured in extremely hot sun and not kept damp to cure.Similar problem when it freezes before it cures. Water changing from liquid state to a solid state assumes a crystalline structure that makes it EXPAND. you see this when ice cubes form in the tray in your freezer. The crystals force the particles of aggregate and portland APART instead of facilitating any bond between them. Later, as the ice thaws, it is free to evaporate into the air just as easily as to enter the chemical reaction, because at low temps, the reaction is occouring so slowly. And with larger spaces between particles caused by the crystals, the overall structure is naturally weaker even if it all went into reaction.Theorectically, the antifreeze avoids the solidification of the liquid water and that damage, but it does nothing to further the actual curing process which cannot proceed without enough heat energy.
   For instance, the fional cured hardness and strength of concrete is calculated partly based on temperature. The other vaariables are time, and mix properties - how much water, portland, aggregate, chemical, etc. Calcium is used to add heat energy to concrete as a sort of antifreeze. Water plus calcium yields heat. but adding calcium to concrete to avoid freezing will carry a cost, not only in dollars, but in final strength, the amt dependent on the actual percentage of calcium used.Similarly, any antifreeze added to mortar will effect teh outcome acording to all the variables, including what the antifreeze chemical actually is, and how it interferes with the ionic bonding that is going on in the mix.here is a site for your own educationhttp://matse1.mse.uiuc.edu/~tw/concrete/prin.html
    

    

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2. 
   Asr | Sep 17, 2005 10:08pm | #8

   Thank you sir, have a great weekend

    

3. 
   Isamemon | Sep 17, 2005 11:24pm | #9

   nice link piffin

   I thought you only did decks

4. 
   Piffin | Sep 18, 2005 01:00am | #10

   Dang, You gotta hang out more. 

    

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2. 
   FastEddie | Sep 14, 2005 05:53am | #2

   What is dutch quality stone , and revierra stone?

    

    

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3. 
   joeh | Sep 14, 2005 06:41am | #3

   There was an article in JLC maybe 2 years ago about this. I think maybe it was the cover?

   Joe H