Concrete Mix for Headworks at WWTP
Concrete Mix for Headworks at WWTP
(OP)
This is for all of you WWTP designers out there. What mix design have you been using for Headworks structures, or other structures with relatively high exposure to sulfates? We have generally been using the same mix design we use for all watertight structures (f'c = 4,500 psi, w/c = 0.42, Type II cement, 6% air) as recommended by ACI350-06 Table 4.3.1 for 'moderate' sulfate exposure, and then recommending the Headworks be lined with a protective coating. But I'm wondering if it might be beneficial to jump to the 'severe' sulfate design mix for the headworks (f'c = 5,000 psi, w/c = 0.40, Type V cement, 6% air) instead. My only concern here is that for some of the small municipalities, Type V cement might be hard to come across. Any thoughts?






RE: Concrete Mix for Headworks at WWTP
Lean towards fly-ash with type 10 because of chloride issues. Type 50 (here HS) is contraindicated for chloride resistance.
Dik
RE: Concrete Mix for Headworks at WWTP
I'd be much more worried about hydrogen sulfide attack on the inside head space of the channels. And there's no concrete mix known that's going to be resistant to that. You're either going to need to put a liner on the concrete (T-Lok) or coat with a hydrogen sulfide resistant coating like Plasite or Sauereisen.
RE: Concrete Mix for Headworks at WWTP