Building Homes or Extensions/Hand mixing concrete

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QUESTION: I am working on a project that requires 4- 16" x 16" x 16" concrete pedestals to be formed and poured. The area which we are doing this work requires this concrete to be hand mixed. While doing some research on the ratio's to be used, I came across several different answers.
My question is what Portland to Sand to Gravel ratio works best for ultimate strength? These pedestals will be supporting approximately 5000 lbs at the four corners.

Thanks for the help,
James

ANSWER: Hi James, why not buy a premixed 5000 pound mix from Home Depot and just add water?

---------- FOLLOW-UP ----------

QUESTION: The project I'm working on is in Tunisia. They don't have premix concrete here so I have to improvise. They have Portland type cement in bags so I am having to hand mix this.

Thanks for the help
James

Answer
Hi again James, sorry, I should have looked at your location a little closer.  A simple 3000 psi mix is 1 part cement, three parts sand and three parts crushed aggregate or rock.  

http://www.everything-about-concrete.com/concrete-mixing-ratios.html

provides some detailed mix ratios for 4000 pound mix and larger quantities like cubic yards.  

3000 psi mix should be more than sufficient to support 5000 pounds over 256 sq. inches.  That's less than 20 pounds per square inch.  What are you building?

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Bruce E. Johnson

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I can answer any construction related question in regards to carpentry, concrete, drywall, masonry, structural elements of any type of building, residential or commercial. Interior or exterior.

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Custom Commercial and residential buildings. Churches, theaters, schools and auditoriums. Most recently I am working with the Catholic Church on several design build committees. I have a website related to scheduling and project supervision. Although my expertise is more related to multimillion dollar commercial, educational and theatrical projects my generous credentials in residential and remodelling construction make me a viable source of information regarding all forms of building questions.

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