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Charli2011

Selitre expert?

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41 minutes ago, RVGRINGO said:

The cement is probably fine, but the sand and gravel used are often the culprits.  After all, CEMEX, supplies all of North America with cement products, but not the stuff you mix it with. In fact, they are a global player in the cement industry.

Thanks RV.  So are you saying that with the standard bags of CEMEX cement with clean silica sand and gravel in the appropriate rations, that 3000 and 4000 psi concrete can be achieved?

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It should, if you mix it properly:  Portland cement and sand at a 1:2 or 1:3 ratio. The 1:2 ratio will yield concrete with about a 3500 pound per square inch compression stress. The 1:3 ratio will yield somewhat less than 3000 PSI, which is typical for house slabs, footings, and sidewalks.

This assumes that you are using clean, washed sand and clean water. For most applications, a crushed stone agragate is used, which should also be clean; preferably granite, not limestone, for example.

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1 hour ago, RVGRINGO said:

It should, if you mix it properly:  Portland cement and sand at a 1:2 or 1:3 ratio. The 1:2 ratio will yield concrete with about a 3500 pound per square inch compression stress. The 1:3 ratio will yield somewhat less than 3000 PSI, which is typical for house slabs, footings, and sidewalks.

This assumes that you are using clean, washed sand and clean water. For most applications, a crushed stone agragate is used, which should also be clean; preferably granite, not limestone, for example.

Thank you for the information RV.  This is very helpful.  Do you think that batch plants in Mexico can be trusted to provide truck fulls of the desired mix ratios for a strong concrete?  Should one hire a contractor who will go to the plant and confirm what is being ordered is delivered?

Thanks again!

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1 hour ago, pedro malo said:

Thank you for the information RV.  This is very helpful.  Do you think that batch plants in Mexico can be trusted to provide truck fulls of the desired mix ratios for a strong concrete?  Should one hire a contractor who will go to the plant and confirm what is being ordered is delivered?

Thanks again!

You can call the concrete plant yourself and ask for the concrete with the desired resistance and slump. They will mix it up and you can have them take a slump test and cylinders for resistance testing 7 and 28 days after. If you are buying a lot of concrete they will perform lab test as part of their service or charge for it if the volume is not enough.

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On March 26, 2018 at 1:47 PM, NachoOE said:

You can call the concrete plant yourself and ask for the concrete with the desired resistance and slump. They will mix it up and you can have them take a slump test and cylinders for resistance testing 7 and 28 days after. If you are buying a lot of concrete they will perform lab test as part of their service or charge for it if the volume is not enough.

I know you can do this NOB but are you suggesting this is the case in Mexico as well?  I think I heard that you must hire someone trustworthy to go to the plant and personally witness and confirm they are mixing the ratio you are paying for.  Was wondering if anyone in MEXICO has had experience with this?

Thank you.

pm

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25 minutes ago, pedro malo said:

someone trustworthy

Yes I do but that is a different story.  If you want that level of assurance, you may have to hire someone like a construction engineer.

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6 hours ago, pedro malo said:

I know you can do this NOB but are you suggesting this is the case in Mexico as well?  I think I heard that you must hire someone trustworthy to go to the plant and personally witness and confirm they are mixing the ratio you are paying for.  Was wondering if anyone in MEXICO has had experience with this?

Thank you.

pm

I've had experience doing this here in Mexico. Working both with Cemex and Cruz Azul. Cemex is a bit more expensive, I have used othee companies but mostly for low resistance not for structural elements (Forza and Moctezuma) . If you still want to test every single truck it might be cheaper to hire CIDI or some other lab to take the samples and do the testing. My own experience using lab testing is a vast majority of the supplied concrete exceeds resistance by a considerable amount. 

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Several years ago I visited a home for sale that had been fully renovated.  One of the things they did was to cut a narrow slot through the plaster running just above the baseboard around the perimeter of every room.  I think the slot was no more than 1/8 inch wide and about an inch deep.  This was supposed to prevent salitre by ventilating moisture out of the wall just above the floor level.

Haven't seen this done anywhere else.   I wonder if it works.

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I bought a ruin in San Cristobal and the engeneer had a tranch cut at the base of the wall and sealed the base and refilled the trench. They opened the wall on a 3f long slot, ditd the process reclosed the wall and opened the next 3 feet. I have had the house for over 10 years and no salitre from the ground..

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On 2/28/2017 at 5:09 PM, NachoOE said:

The best solution is to remove wall plaster, let it dry a couple of days. Apply muriatic acid (1 part acid to 3 water) to the wall, allow it to dry. Apply another hand. Replaster leaving a 1 inch gap at the bottomn apply acid to the plastered wall. Let it dry, and paint. After each acid application you have to wash the wall will water.

I wound up hiring this person as a result of him responding to my request for information on a building product ...  that I now know to be Hebel.  I did not know that he had been posting various places on this board ...  which looks like he was trying to generate some work for himself.   That's not necessarily a  problem ........    He responded to one of my posts for information on Hebel.  We met, I interviewed  him, got some references,, etc.  It was not enough.  After 6 months building a home, he was separated from the project without any recommendations from  us. If anyone is thinking about hiring him, you are welcome to contact me via a PM.

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