concrete slump for SOG

[a2mfk]

Wondering what you ladies and gents are specifying these days for slump. We currently call out for 4" max slump for all concrete, except 3" for SOG. Its been in our general notes for a long time and I honestly don't know where it came from. Never had a question, comment, problem or concern, but a peer reviewer (SE) that I respect said these are "very low slump numbers".

To avoid tangents and long theoretical concrete mix discussions, I know the answer could be "it depends on ____", especially the mix design. But just looking for your typical slump range for the following that you may have on your general notes for average projects. We are in Florida, USA if that helps.

Footings-
SOG-
Tilt-Panels-
Concrete on elevated slab-on-deck (composite slab)-

 

[Ron]

a2...it depends on how you get the slump! If the slump is obtained with a plasticizer, then 5" +/- 1" is fine. If the slump comes from water addition and a compromise to the w/c ratio, then keep the slump low.

In short, it depends on the mix design.

 

[a2mfk]

Dangit Ron! I knew you were going to respond just like that

In short, what about modifying our general notes allowing the mix design to add plasticizers and allow an increase in the slump, submit mix design for review?

 

[Ron]

EXACTLY! Specify a slump of 4" (under ASTM C94, that gives a +/- of 1". The state that if greater slump is required for placement, then plasticizers (high-range water reducing admixtures) must be used. Submit mix design for either or review.