Does anyone allow AEA to be added to concrete at the job site?

[Hemifun]

I have a project going on right now that had a concrete pour last week where the entrained air content was consistently low. The plant kept adjusting the AEA(air entrainment admixture) but still stayed on the low side. The contractor has asked me if we still low air on the additional pours if he can add the AEA to the truck on site. My initial reaction is to deny that request but told him I would look into it. So, has anyone ever done this? Any suggested guidance on this request? Thanks.

 

[DWHA]

Yes, I have seen this done on many bridge projects in Illinois.

 

[larsacious]

It is not uncommon to add AE at the jobsite. In fact, I prefer they add AE instead of water to raise air content. You should instruct the contractor to have the QA person from the ready mix plant be on site to add the AE. Be sure they give 20 at least revolutions before testing the air again. Do not direct them on how much AE to add and warn them if the air is too high and out of spec after adding AE you will need to reject the truck.

 

[Ron]

Agree with larsacious...can be done, but keep the ReadyMix supplier involved. Have their QA person there to make the adjustments. Keep them in the responsibility line for the mix. Don't take it upon yourself or allow the contractor to do so.

 

[beton1]

Agree. It can be done, (superplasticizer is sometimes prepared in appropriate size container and added at site). But keep the concrete supplier on this, they should adjust the concrete mix design if this is a consistent issue. Get them to send their quality control on site to also test air (if not done already).