Increasing concrete mix slump using ad mixture

[AskTooMuch]

I've read in concrere mix guides you can't increase slump using water, of course. It also statea use admixture instead, that's it.

I've not seen a guideline about increasing slump using ad mixture like what's the maximum slump if using admixture, etc..
All other specs are met (concrete strength, etc..)

 

[phamENG]

Usually 8 inches for standard concrete with admixtures. Depends on the application, though.

 

[r13]

I suggest to get acquainted with PCA (Portland Cement Association), which excels in concrete mix design.

 

[jayrod12]

Oh generally speaking 8" is a reasonable number. However some of the self-consolidating type mixes exceed that. They're chocked full of water reducing admixtures and other improvements to ramp up flowability without segregation. But it's a fine line.

 

[r13]

Strictly to say, there is no limit on slump IF the mix can achieve the desired strength, and meeting quality and workability criteria. Uncontrolled use of admixtures is harmful to concrete instead of help, if I remembered correctly.

 

[Divyakumar Vasani]

Hello guys Read this following article for <a href="

https://www.civilquery.com/what-is-admixture-in-concrete/">Admixture

in Concrete</a>. How its effects the mix design

 

[RWW0002]

Strictly to say, there is no limit on slump IF the mix can achieve the desired strength, and meeting quality and workability criteria

The 8" limit above is reasonable. There area guidelines for increasing slump to the point that it is essentially infinite and is measured in slump flow instead of slump (see self-consolidating concrete) but there can be major issues with aggregate segregation and concrete performance if the mix is not proportioned correctly

I would stick with around 8" max as a good rule of thumb. Unless you are familiar with self-consolidating concrete, some of the fresh concrete properties that should be monitored are not typically measured or understood. Just dosing up a mixture with superplasticizer is a recipe for disaster.

 

[r13]

Note that I am not against, nor for, the 8" max, I think set the slump to fit the work and workability are more important, sure, at the premise that no quality would be compromised. Below is an excerption from PCA, interested person can follow up for more information.

Superplasticizers, also known as plasticizers or high-range water reducers (HRWR), reduce water content by 12 to 30 percent and can be added to concrete with a low-to-normal slump and water-cement ratio to make high-slump flowing concrete. Flowing concrete is a highly fluid but workable concrete that can be placed with little or no vibration or compaction. The effect of superplasticizers lasts only 30 to 60 minutes, depending on the brand and dosage rate, and is followed by a rapid loss in workability. As a result of the slump loss, superplasticizers are usually added to concrete at the jobsite.