"1:2:4" Concrete Strength
"1:2:4" Concrete Strength
(OP)
I am analyzing some existing structural damage an old condo building from 1938 where the original drawings specify all concrete to be 1:2:4. This building was also designed under the WSD design method.
If my memory serves me correctly, I believe 1:2:4 was very common for the time and would extrapolate to about 2000 to 2500 psi concrete today.
Can anyone verify that or shed further light on the issue? I do not have my older info from the City of Seattle with me right now.
If my memory serves me correctly, I believe 1:2:4 was very common for the time and would extrapolate to about 2000 to 2500 psi concrete today.
Can anyone verify that or shed further light on the issue? I do not have my older info from the City of Seattle with me right now.
Mike McCann, PE, SE (WA)






RE: "1:2:4" Concrete Strength
http://www.concrete.org.uk/fingertips-nuggets.asp?...
Mike McCann, PE, SE (WA)
RE: "1:2:4" Concrete Strength
Does the structural damage warrant undertaking concrete cores to be more definitive of the compressive strength?
RE: "1:2:4" Concrete Strength
Looks like the courtyard was spec'd for 2 feet of earth, but I measured 4 feet. => problem... Only an additional 230 psf of load...
Mike McCann, PE, SE (WA)
RE: "1:2:4" Concrete Strength
Just to keep everyone shaking their heads, My father & I used that proportion to place some in-fill slabs around the house in 1968, kept the slump low and had 4000 psi concrete.
RE: "1:2:4" Concrete Strength
RE: "1:2:4" Concrete Strength
See attached catalog from Atlas Cement Co. (dated 1926; you must've been out when the salesman was there that day
Table 14 on Page 14 has 7-day, 28-day, and 6-month strengths for 1:2:4 concrete and a few other mixes.
RE: "1:2:4" Concrete Strength
RE: "1:2:4" Concrete Strength
RE: "1:2:4" Concrete Strength
I guess you are showing your age too, aye matey?
Thanks for the link. That is great!
Mike McCann, PE, SE (WA)
RE: "1:2:4" Concrete Strength
You're quite welcome AND you're absolutely right - I was thinking the same thing today. I worked on two bridge projects recently - one was built in 1940; the other in 1941 - these were the earliest plans where I came across the names of people I worked with.
RE: "1:2:4" Concrete Strength
In general, I agree, but always through the veil of common sense and good judgement.
RE: "1:2:4" Concrete Strength
RE: "1:2:4" Concrete Strength
Party Pooper! Good to know. Most of my evidence is from contractors trying to cut old concrete or install Tapcons where they easily break. Never had any tested, however.
RE: "1:2:4" Concrete Strength
Unrelated but give me a couple weeks and I will have over 40 cores tested with the same specification, not it will help you.