Forums > Specific Focus > Home, Garden & Construction in Mexico> Re: [Bennie García] Percentage of Cal is Best for a Strong Concrete Mix for Cantara Stone Wall and O

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robt65

Nov 17, 2011, 7:40 PM

Re: [Bennie García] Percentage of Cal is Best for a Strong Concrete Mix for Cantara Stone Wall and O

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Hello Bennie,

I am really just checking up on my workers (not as in questioning their knowledge but rather trying to learn some of their methods and the reasoning behind those methods.

The four of them are doing really good work and the boss man has been at it for years so I am not questioning him, but the mortar mixes and cement mixes here are far different from NOB for sure. And I guess I am a little baffled by them. NOB at least in the Tennessee Valley area including Kentucky and parts of West Virginia, & most of Georgia there is not any use of "Cal" (as it is known here) that I am aware of in a Concrete (not mortar) mix for stone walls, but there is a lime (not calcified in some cases) used along with different sizes and grades of a washed sand or silica sand: gravel is of course not used and all of this depends on the varying loads of tonnage per sq., yard of stone and kinds of stone as well as the current weather.

I have learned that apparently "Cal" as it is called here in the Queretaro area is used with a four bag Cal to one bag cement mix and a certain amount of good washed sand to make what these workers are calling a "cement" mix. To me it is more of a concrete slurry, but certainly not a “mortar” mix as I know mortar mix (with clay and not cement) to be.

Apparently it has something to do with controlling the constant (medium) and not rapid curing of the concrete mix (slurry) they are using. It is more reasonable in material cost for sure and that is great for my purpose, but I was concerned it maybe was not as strong when finally cured.

Evidently up here in the higher altitude along with the normally dry climate “Cal” controls the curing rate so the mix does not cure to rapidly, so as not to cause premature cracking. It also appears to be an easier working substance using the “Cal”. They are a great crew, but I was really caught off guard with the amount of "Cal" in the mixture.

Actually a pure mortar is really a "clay mixture and many times a pure Kaolin clay in the mixture and not a cement, however many masons do use what they call a cement mortar.

A usual specification mix we would call for on such large stone project specifications would traditionally be 2 parts Portland Cement, 1 part Mortar clay and six parts washed or silica sand, using a highly plastic mortar clay actually considered to be a “Kaolinic” mortar clay, for stone laying or large freehand fired brick laying.

I have also noted a great amount of efflorescing taking place here in the Querétaro area on on relatively young facilities. This is usually caused by water reacting to the salts used in some concrete, concrete slab or block or bricks. It usually shows in a flowering crumbly white powder, when touched. Sometimes it can be seen as a “blistering” beneath a painted surface. I was also wondering if this may be caused by the amount of “Cal used I the local mixes. I just don’t know for sure.

Anyway this is why I was asking. Thanks for your response, I appreciate it.

robt65

(This post was edited by robt65 on Nov 17, 2011, 8:03 PM)

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Post edited by robt65 (Veteran) on Nov 17, 2011, 8:03 PM