Forums > Specific Focus > Home, Garden & Construction in Mexico

robt65

Nov 16, 2011, 7:39 PM

Post #1 of 18 (4277 views)

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Percentage of Cal is Best for a Strong Concrete Mix for Cantara Stone Wall and Other Building Projec

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It seems that there are as many different formulas for a strong concrete mixture as there are different moles in Mexico! What mix of cement, sand, gravel and "Cal" would you use to build your wall and why? I am not used to using any "Cal" in concrete mixtures . . . at least by that name. I am sure it has a specific use here in Mexico for a specific reason and I seek a little education in this subject.

Also, it appears that many folks here use a concrete mix for setting ceramic tile floors in their homes and evidently there are certain tiles that are made specifically to be used with concrete and others that are not. How does one tell the difference and what are the ramifications, pluses or minuses for using concrete as a base for setting a ceramic floor in general living spaces outside of the bathrooms?

thanks,

robt65

(This post was edited by robt65 on Nov 16, 2011, 7:41 PM)

Bennie García

Nov 17, 2011, 6:41 AM

Post #2 of 18 (4252 views)

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Re: [robt65] Percentage of Cal is Best for a Strong Concrete Mix for Cantara Stone Wall and Other Bu

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What you are looking for is mortar and not concrete.There is no gravel in mortar. You can buy bags of premixed mortar which is cement with added plasticiser (which is what lime is) and all you add is sand and water. If you want to use cement and lime then there are different formulas depending on what you are using it for. The type of sand also must be considered.

Thick clay tiles such as saltillo are often set in a thick mortar bed similar to what is used for laying brick. Thin hard glazed tiles are laid with thin set tile adhesive which comes premixed.

YucaLandia

Nov 17, 2011, 3:21 PM

Post #3 of 18 (4227 views)

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Re: [robt65] Percentage of Cal is Best for a Strong Concrete Mix for Cantara Stone Wall and Other Bu

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Robert,
Google self-healing concrete. The cal helps the concrete heal cracks in the future.

Are you needing mortar mix for setting stones in a wall? That's a different product: different cement and different materials than concrete. See Cemex N, S, or M product specs: http://www.cemexusa.com/...nto/pdf/type-nsm.pdf

You also mention tile work, which points to yet a different mix: pegazulejo.

Here in Yucatan, the terra-cotta style tiles are set in mixes that resemble mortar mixes.

Each of these types of cement have very different properties than the concrete used for flat-work,
steve
=
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Read-on MacDuff
E-visit at http://yucalandia.com

(This post was edited by YucaLandia on Nov 17, 2011, 3:26 PM)

Bennie García

Nov 17, 2011, 4:35 PM

Post #4 of 18 (4216 views)

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Re: [robt65] Percentage of Cal is Best for a Strong Concrete Mix for Cantara Stone Wall and Other Bu

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Like I said in my first post. Concrete isn't what you are looking for. Mortar mixes, whether premixed in the bag or mixed from scratch depend on a number of factors. You need to be careful with lime, too much and it will set too soft. Too much and you might have a salitre problem. Especially if you use a thick mortar bed (I recommend this method) for laying saltillo type floor tiles.

robt65

Nov 17, 2011, 7:40 PM

Post #5 of 18 (4204 views)

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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)

robt65

Nov 17, 2011, 7:59 PM

Post #6 of 18 (4200 views)

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Re: [YucaLandia] Percentage of Cal is Best for a Strong Concrete Mix for Cantara Stone Wall and Othe

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Hi Steve,

Thanks for the CEMEX PDF spec site. that really is a big help. I had forgotten all about that American version as we were never allowed to buy "foreign" associated products in our particular government projects at the time. Thanks also for the tile references.

robt65

Bennie García

Nov 18, 2011, 6:36 AM

Post #7 of 18 (4180 views)

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Re: [robt65] Percentage of Cal is Best for a Strong Concrete Mix for Cantara Stone Wall and Othe

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1 part portland cement, 4 parts cal (hydrated lime) and 5 parts sand is a common mix. I am not sure what your definition of slurry is. We use cement slurries, just cement and water, and it is mixed at about the consistency of yogurt. The mortar your workers are preparing should be thick enough it will keep its shape until spread by the trowel when laying up the wall.

robt65

Nov 18, 2011, 6:53 AM

Post #8 of 18 (4177 views)

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

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YucaLandia

Nov 18, 2011, 7:24 AM

Post #9 of 18 (4169 views)

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Re: [robt65] Percentage of Cal is Best for a Strong Concrete Mix for Cantara Stone Wall and O

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Robert,
The efflorescence has 2 common causes:
1. If there is no moisture barrier laid down between the foundation and the wall, then ground moisture (water) is wicked up into the wall and dissolves some poorly crystallized calcium - from too much cal - and it moves to the surface as Cacium salts = > weak walls.

2. When the concrete or mortar is mixed with too much water - as seems common across Mexico with most albiniiles hand-mixes -> as the concrete cures, the excess water causes uneven curing, with pockets of moisture collecting - that never cure right - where the water then leaches out the unbonded-uncrystallized Calcium making patches of efflorescence => weak concrete.

So, some cal helps in self healing, but the common practice of pouring slurries or soupey concrete makes a product that is ultimately weak and that gets weaker over time. These methods of making concrete and mortar do not fit even the Mexican cement instructions on their bags => cheaper but a poorer performing product for its entire life.

Notice how Roman concrete and properly mixed concrete gets harder and harder over time, until the concrete that my great grandfather and grandfather poured is so hard that I can't drive a nail into it, while the common albinile-hand-mixed home-made-up-formula concretes do not cure properly, have a lot of unnecessary efflorescence, are weak, and get weaker over time vs. stronger over time.

So, by substituting Cal for cement and by making a soupey slurry to make it easier and faster to handle (less bubbles to have to work out) and much easier and faster to finish - many common guys create a weaker product that does not perform well.

Concrete mixes - supervised and designed by civil engineers that is commonly used for roads and bridges and large buildings does not have these issues, because the Redi-Mix plants and civil engineers follow the manufacturers instructions and use the products as they were designed => strong mixes that do not have weak incomplete crystallization, and do not have the efflorescence and additional weakening over time due to the interstitial unbonded Ca salts.

Fortunately, the home-made ad hoc formulas are not typicaly used to bear heavy loads, so, I guess it works out => cheaper lower grade product that you can slap-up quickly, that serves the purpose - for 5-6 decades, except for the efflorescence? But still the amount of prematurely cracking concrete here is shocking.
steve

s s => weak > w
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Read-on MacDuff
E-visit at http://yucalandia.com

Bennie García

Nov 18, 2011, 7:47 AM

Post #10 of 18 (4162 views)

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Re: [robt65] Percentage of Cal is Best for a Strong Concrete Mix for Cantara Stone Wall and O

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I promised not to respond to yucalandia's posts but all they really contain are opinions based on information gathered from Google. It might be helpful if he would refrain from posting on subjects he has absolutely no experience or personal knowledge of.

YucaLandia

Nov 18, 2011, 5:47 PM

Post #11 of 18 (4136 views)

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

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In Reply To

Hey Bennie,
You should have kept your promise to yourself. You have imagined things that are a bit off the mark.

My sources?
My dad: Owned and ran a paving business from 1948 - 1996 in Washington DC. He was a fine fine non-degreed engineer. Even his oldest concrete jobs from the 1940's and 1950's are in much better shape 60 years later than just 10 year old home-spun concrete work and home-made formulations that I've seen over the past 25 years visiting and living in Mexico.

My Grandfather: built 3 houses, including the concrete basements and foundations. Again, 80 years later, his concrete work is still far far stronger than anything I've encountered that's made by typical albiniles and their personal mixes that ignore the manufacturer's instructions.

My Sister in Law: One of the top 3 Architecture students at graduation. and a general contractor for masonry and concrete building projects since 1982 here in Yucatan. I spent 6 months working with her guys to find out how concrete things are done here.

My Father in Law: A degreed Civil Engineer, who did 40 years of concrete roads and bridges projects. This guy was also the official Chief Carreteras y Puentes Inginero for Yucatan - the state with the best roads in Mexico.

He did such a good job in Yucatan State, that Campeche State hired him for the same job - Chief Roads and Bridges Engineer to design a modern roads and bridges system for Campeche State.
next?
This same concrete Engineer was invited to be the Chief Engineer for Roads and Bridges in Tabasco...
and
Then this same suegro was invited to Guerrero to... wait for it ... design and build concrete roads and bridges in Guerrero.
If you know the recent-past engineering history of Mexican concrete engineers, you might have known mi suegro. There are nice placas placed in public areas around Mexico - including Ciudad México.

This sweet man was given National Honors from the Mexican Government for his exceptional service to the Nation. Guerrero just last month had a special celebration of their roads and bridges programs. and guess what? Since mi suegro is now dead, they paid to have his daughter, mi esposa. come and receive public honors for his contributions.

In addition to these fine family members, I also get information on current concrete methods and programs from the top Civil Engineer for Yucatan Peninsula's largest private roads & bridges construction firm - my brother in law .... This brother-in-law is currently building/improving the latest highway project south out of Cancun - replacing the previous guys who - screwed up the concrete work - so, they invited in my brother-in-law to clean up the mess....

" It might be helpful if (Dr. Fry) would refrain from posting on subjects he has absolutely no experience or personal knowledge of"

In addition to the learning I have gained from these fine fine engineers and contractors who spent their entire careers working with ... concrete.... I spent a measly 9 summers doing.... concrete work... as a 60 hour per week paving laborer. I also have continued to pour patios, driveways and sidewalks as small projects since then, and I have done a little masonry work too since moving to Mexico 6 years ago.

As a Doctor of chemistry and materials sciences expert, I have also formally analyzed and studied concrete and its properties.

'nuff said about your imaginations of Google Searches as the source of my information - and that I have no experience?

I really must thank you Bennie, for the chance to think warmly of my beloved engineer-parientes: my father and my father-in-law - both loving and wonderful and very talented men. I was very lucky to experience their influences and benefit from their fine efforts. If you know the recent-past engineering history of Mexico's top concrete engineers, you might have known mi suegro.

steve
-
-
Read-on MacDuff
E-visit at http://yucalandia.com

Bennie García

Nov 18, 2011, 6:48 PM

Post #12 of 18 (4122 views)

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

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That's quite a resumé!!

But with such a wealth of knowledge to draw from forgive my surprise at the following quote from one of your prior posts (bolding mine):

Quote

Notice how Roman concrete and properly mixed concrete gets harder and harder over time, until the concrete that my great grandfather and grandfather poured is so hard that I can't drive a nail into it, while the common albinile-hand-mixed home-made-up-formula concretes do not cure properly, have a lot of unnecessary efflorescence, are weak, and get weaker over time vs. stronger over time.

So, by substituting Cal for cement and by making a soupey slurry to make it easier and faster to handle (less bubbles to have to work out) and much easier and faster to finish - many common guys create a weaker product that does not perform well.

Because it seems odd you wouldn't know that for the Romans and others for centuries that followed, lime was the main ingredient of their cement, concrete and mortar.

Lime mortar was used pretty much exclusively up until Portland cement came along when it was first added to speed up the set time.

Since you are obviously an expert on concrete construction and spent 6 months working with your SIL, and love to make long, linformative posts, explain how a typical house is built here. (Don't go Googling now. That would be like cheating at Solitaire). A step by step explanation. Start us off with the foundation and take us all the way up through the roof. Materials, techniques, different cement and concrete mixes etc. Necessary compression strength, slump testing and a rebar schedule should be included. Some detailed information on the different aggregates used in your area. Include specifics on the workability of your mortars. The different kinds of brick and block plus their differences and properties.

I know I am not alone in anxious anticipation of your response.

P.S. It is spelled albañil

YucaLandia

Nov 18, 2011, 7:43 PM

Post #13 of 18 (4112 views)

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

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Hi Benny,
There is no need for me to explain things that you already know. This is not a contest of knowledge.

You claimed that I had no personal experience with concrete.
I offered facts that show I do have personal experience with concrete, so, that other readers could decide whether to follow your advice or to follow your empty criticism of my advice. People can determine for themselves who they want to believe or trust.

You said I get my information only from Google.
Your imagined sources of information helped me think of how blessed I have been with the aid, teaching, and support of some very special men and women, helping me reminisce about some very gracious, talented, and knowledgeable people. Your efforts to enlighten everyone had the side benefit of reminding me of how lucky I am to have a terrific family of 2 generations of Mexican builders and construction professionals.

I am so very proud to be a part of talented and gracious families in both Mexico and the US, and very blessed by all my family members. We never know what will pop-out when someone pushes.

Thank you again for reminding me of all the blessings in my life, and also for reminding me of what is important in life.
steve
-
-
Read-on MacDuff
E-visit at http://yucalandia.com

Bennie García

Nov 18, 2011, 7:52 PM

Post #14 of 18 (4108 views)

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

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In Reply To

There is no need for me to explain things that you already know. This is not a contest of knowledge.

It really wasn't for me. I was sure you would be happy to expound on the subject for the benefit of others ion the board just as you have with so many other topics.

Sculptari

Nov 19, 2011, 11:38 AM

Post #15 of 18 (4078 views)

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

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Roman cement contains pozzolans, which even until this day, the best comes from Italy. It was specified, for example, in the concrete support pylons for the Vancouver "subway". In North America we use Fly Ash, a byproduct of coal power generation.

Lime, Cal, does not "cure" in the typical sense, it slowly absorbs carbon dioxide from the air. Every application varies. Sometimes we use a high lime content to cushion heavy stones, especially in an area of vibration (nearly everywhere today near roads). It is important that the grout be softer than the stone or brick, you want the mortar to fail before it cracks or breaks the masonry.

There are many types or classifications of lime. There is a good Mexican website on this, but I cannot find the bookmark right now. As mentioned, a 100 year old piece of cured lime cement is harder than you can imagine (again, endangering what may be irreplaceable masonry)

Of all the cements ever developed, Portland cement is the least desirable, and it's introduction to the world is a tale of dishonesty, corruption and untold ecological damage.

Bennie García

Nov 19, 2011, 1:05 PM

Post #16 of 18 (4071 views)

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

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Yes puzolana, as it is called in Spanish, was an ingredient in the Roman's masonry. Puzolana is readily available here and was still used frequently in mortar mixes in the not too distant past. Like just about everywhere else, portland cement mortar mixes became the standard. Lime was added to add workability and flexibility and the mix doesn't set as quickly so a larger batch can be prepared which is the opposite of portland cement mixes. Kind of ironic. People went to the cement mortars becasue they set faster. Now some add more lime to keep it from setting so quickly although not necessarily for the right reason..

Sculptari

Nov 20, 2011, 8:54 AM

Post #17 of 18 (4042 views)

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

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In Canada, the U.S.A., and probably Western Europe, the price of skilled labor far outweighs the price of material, Instead of lime, we add chemical 'plasticizers' and/or retarders, there are many to choose from. In the freezing areas, we also add a little foaming agent because a few air bubbles seem to vastly improve frost resistance.

Portland cement's big and only advantage as far as i am concerned, is resistance to water while setting in its early stages. Early cement likes to be wet, but I never see Mexican masons following this rule. It is at home in a cool. wet environment. The magnesium based cements are far superior in every aspect, and are commonly used in India and China. Some engineers, with too much time on their hands, have calcuated that if the world had adopted magnesium cement instead of portland cement, to build it's roads and cities, that there would be no global warming/ozone holes. Magnesium cements, like lime, suck carbon dioxide from the air to cure. The problem is getting CO2 deep into a large pour. This is easily solved by adding a CO2 filled foam into the mixture.

morgaine7

Nov 20, 2011, 9:19 AM

Post #18 of 18 (4038 views)

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

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Quote

Early cement likes to be wet, but I never see Mexican masons following this rule. It is at home in a cool. wet environment.

Whenever I've had concrete work done, the albañiles have asked me to hose it off 3-4 times a day while it's setting. Or is that something different? This is a sunny, very dry climate during most of the year (Baja California Sur).

Kate