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Re: Concrete Exposed to Sulfates[Subject Prev][Subject Next][Thread Prev][Thread Next]
- To: seaint(--nospam--at)seaint.org
- Subject: Re: Concrete Exposed to Sulfates
- From: "Bill Sherman" <SHERMANWC(--nospam--at)cdm.com>
- Date: 12 Feb 99 10:11:11 -0500
RE: Questions by Steve W. regarding applying or interpreting 1994 UBC Sec. 1904.3 and Table 19A-3: 1. If sulfates are known to exist, do you call out both the water-cement ratio and the concrete strength per T-19-A3? Yes, both should apply. Note that the second half of the sentence in 1904.3.1 reads "maximum water-cementitious materials ratio and minimum compressive strength". But this raises another question for me - what is the difference between the first and second half of 1904.3.1 (as separated by the word "or")? 2. If the required concrete strength per the Table is greater than the design strength, which may very well be the case, do you require special inspection to verify? How do you verify the water-cement ratio? I would confirm the water-cement ratio in the concrete mix submittal and verify the compressive strength the same as if it were the design strength via test cylinders. 3. If the foundation system is not required to be designed/engineered, such as a conventional framing foundation, would the sulfate exposure requirements of Chapter 19 be applied? Section 1802 seems to require all concrete foundations must conform to Chapter 19. The provisions have to do with durability, not stress design. Therefore they apply regardless of whether it is an "engineered foundation". 4. If you have sulfates and you design/engineer a portion of a foundation (and provide the strength and water-cement ratio for that portion) would you also provide the same for adjacent non-engineered footings? Yes. 5. What do you tell the owner about the cost of all this testing? What do you tell the contractor when he can't pump or work the .45 water-cement ratio concrete? Regarding the owner, I'd note that these are code requirements and that they are to ensure that the foundation will not prematurely deteriorate - thus it is for the owner's benefit. Regarding the contractor, the concrete can be pumped with use of appropriate admixtures.
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