Need a book? Engineering books recommendations...

Return to index: [Subject] [Thread] [Date] [Author]

Re: Concrete Exposed to Sulfates

[Subject Prev][Subject Next][Thread Prev][Thread Next]
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.