minimum concrete strength
minimum concrete strength
(OP)
Does ACI list a minimum f'c value for concrete footings?
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minimum concrete strength
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RE: minimum concrete strength
See 1.1.1, 5.1.1, 19.3.1, 21.1.4.2, 22.2.3
Nonetheless, from 5.1.1, it states:
Concrete shall be proportioned to provide an average compressive strength, f'cr, as prescribed in 5.3.2 and shall satisfy the durability criteria of Chapter 4. Concrete shall be produced to minimize the frequency of strength tests below f'c, as prescribed in 5.6.3.3. For concrete designed and constructed in accordance with the Code, f'c shall be not less than 2500 psi.
I usually have footings designed for 3000 psi though.
RE: minimum concrete strength
As with ISCK, I typically use 3000psi.
RE: minimum concrete strength
can someone scan me the 2008 version of 5.6.5 for low strength tests? i don't have the 08 version
RE: minimum concrete strength
This means:
1)go to books.google.com
2)search for "aci 318"
3)the search results will give you link to the limited preview of ACI 318-05
4)click on that link
5)on the upper right hand corner, it says "search in this book"
6)type in 5.6.5
7)results will show page 67
8)click on that
9)use the left and right arrows on the top to go to page 68
I've looked over page 68 and 69 of the ACI 318-05 and ACI 318-08 in the Code column for 5.6.5. The difference is pretty much in the wording of 5.6.5.3
ACI 5.6.5.3 states:
Cores shall be obtained, moisture conditioned by storage in watertight bags or containers, transported to the laboratory, and tested in accordance with ASTM C42. Cores shall be tested no earlier than 48 hours and not later than 7 days after the coring unless approved by the licensed design professional. The specifier of tests referenced in ASTM C42 shall be the licensed design professional.
As always, we'll need to reference these codes often, so it's best to buy a copy of the ACI 318-08. Some structural websites or companies will often post the "Significant changes" to ACI 318-08 online, so that those who have the ACI 318-05 can adjust accordingly with their engineering judgment.
See these links:
htt
http://www.gostructural.com/article.asp?id=2919
h
I hope this helps.
RE: minimum concrete strength
Why do you want to spec a low strength concrete? The current applicable codes do not rference the '08 documents, but will in a year or so.
If you are looking at something that is easily removable there are other types of concrete.
The material cost savings are negigile between 2500 psi and 3000 psi and will probably get the same concrete if you just specify a minimum strength. The cost to place and finish is the same, so any savings is negligible and reduces and cushion in the design.
If it for residebtial construction, 2500 psi is a common minimum and may not require any reinforcement since a narrow strip footing rarely has a need for reinforcement. The footing is only to privide a clean, level surface to build off of.
Dick