What are basic cement mixing rules?


  #1  
Old 12-22-05, 02:59 PM
J
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What are basic cement mixing rules?

I'm patching an old cement basement wall. Someone here once recommended "parging" and using 1 part portland cement to .9 parts sand and water to the consistency I need. I find that this mixture gives a surface a bit rougher than the surrounding surface(which is gritty but not rough) and I'm wondering about varying the mixture.

How would the surface vary using different sand amount, and also what would the effect be using just the portland cement and water. And should lime be added to this mix? I have no real basic knowledge about this process and I'd appreciate hearing from some experienced persons about the effects of different mixtures.

John
 
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Old 12-22-05, 03:09 PM
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Using just portland cement and no sand would be a mistake. It would be very weak and brittle and would just flake off. Whenever I've parged, I mixed about 1.5 to 2 parts sand (fine grained sand, like play sand) to 1 part portland cement. If you want it to stick better, mix in some acrylic bonding agent like Acryl 60 or similar. Then apply it to the wall with a rubber float. It's like a stiff foam rubber sponge with a handle. I like the more rigid black ones better than the softer red ones. I have always found that the mixture sticks and cures better when applied to a slightly damp surface. You can vary the texture with the rubber float.

Pecos
 
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Old 01-03-06, 11:47 PM
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us finishers call this rubbing and patching , you need a rubbing stone , margin trowel and rubber sponge float . rub the areas to be patched with the rubbing stone as if you were sanding it , get out all loose debree and wet with house sponge use a cement patch compound they sell it at a concrete supply store and the curing-bonding liquid you mix with it (it looks like milk) mix it up in a 5 gallon bucket use your margin trowel to fill the hole and float over with the rubber sponge float( if you want a smooth finish then instead of hitting with your rubber float hit it with a finishing trowel ) take note this stuff we use on commericial jobs its strong & sets up fast and works great on residential basements
 
 

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