concrete mix
concrete mix
(OP)
I am looking a set of structural drawings from 1918. The concrete mix is called out as 1:1:2 and 1:2:4. Does anybody know what this means? What would be the corresponding strengths of concrete?
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RE: concrete mix
I looked in a 1919 edition of "Trautwine", but could find no reference to the strength. I found only a general estimation formula, but nothing specific.
If you do not have a meter to determine the f'c, you might consider taking and testing two or three core samples.
Mike McCann
McCann Engineering
RE: concrete mix
As Mike said, consider a few cores if necessary. It's possible that they might come up higher than 2000 psi.
RE: concrete mix
RE: concrete mix
For a 4 inch slump and about 36-38 gal of water/cu.yd...no admixture..SGs of cement and aggregate at 3.15 and 2.65 respectively, loose unit weights of cement and aggregate of 94 lb/cu.yd and 100-105 lb/cu.yd:
1. The 1:2:4 mix would approximate a 5scy mix with a W/C of about 0.67. I'd say that might work for a f'c of between 2000 to 2500 psi at 28 days. The in-situ concrete is much older now.
2. The 1:1:2 mix will be much richer in cement and have a mcuh lower W/C ratio than the 1:2:4 mix....less than 0.40. Consequently the f'c requirement will be higher than the 1:2:4 mix. Was this used for beams and columns?
All the same, I support the suggestion that cores be taken to evaluate strength.
RE: concrete mix
RE: concrete mix
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based on my fathers old british Reinforced concrete Designer's handbook, 1:1:2 concrete is typically high strength for it's time and is between 4000 to 4500psi.
1:2:4 concrete is standard concrete at 3000psi.
RE: concrete mix
RE: concrete mix
Since the building is approx. 100 yrs old, my suggestion is to test some concrete cores. There can be deterioration due to carbonation etc.