Slump of Pump Mix Concrete!

[engr567]

Where can I find the allowable slump for pump mix concrete using high range water reducer? We have specified a slump of 4"+/-1" at normal condition - 4000 psi and 5000 psi concrete (cast in place parking garage). Concrete mix design indicates 8" of slump. I would appreciate help.

 

[gosai]

The slump of the concrete is contractor's item which depends on the site requirements and method of placement. When contractor need higher slump then specified they request the supplier to use superplastisizer to increase slump. Supplier maintain the slump prior to addition of superplasisizer.

 

[TXStructural]

Using a high range water reducer (and ideally, a viscosity modifier to keep aggregate in suspension), you may end up with anywhere from 8" to something which is too fluid to be measured by slump testing. Since slump is simply a QA measure for water-cement ratio and workability, once the WRA is added, you can't really test for these.

Your admix supplier and ready mix supplier/designer should be able to provide advice. On small jobs, you may be able to add the admixtures after checking an initial slump (depending on admix). On large jobs, the supplier should provide test data on the mix design as part of submittals.

 

[engr567]

Thanks both of you.