Excessive Retardation of Concrete - any articles or papers?

[Ndtman]

I am trying to help a client who has had a problem with excessive retardation of concrete in drilled shafts (piles).
When tested by sonic logging at 7 days some of the concrete had low UPV. When retested at 14 days UPV had increased by 50 percent. The mix was self-consolidating (9 inch slump) with double the recommended dose of Master Builders Pozzolith 300R. I am looking for any conference papers or journal articles describing similar experiences. Can anyone point me in the right direction?

 

[kjde]

Very less is available on this subject but personal experience has shown that lignosulphonate based admixtures behave this way when a phospho gypsum is used during cement grinding process. The concrete will regain its full strength at 28 days for sure.