hard concrete and glenium 7500

[bridgeman5858]

I am currently usen a 4000psi mix that has glenium 7500 in it my problem seems to be that 1, I can only have a2inch slump plus 1 and when we add any water it dryes to fast and cant vibrate it the other fast is it is being added at the plant witch is 35 min away the amount of glenium 7500 is 9oz per gal. is this right? the weather is 41 deg.Do i have to use it and will it change the mix design help......

 

[Ron]

It sounds like you are having at least two problems with your mix...

First, the dose rate is 9 oz. per 100 lbs of cement, so if you have a 4000 psi mix, you likely have about 600 lbs of cement per cy, so you probably have about 50 to 60 oz/cy of Glenium 7500. Your dose rate is about right for most applications; however, it appears your dwell time is being affected by the haul time from the readymix plant. Since all of your other units are in US conventional units, I will assume that the "41 deg" is Fahrenheit. If that's the case, you should not be getting set times so quickly as you've described.

You mentioned that when you add water, it "dries up fast". This indicates that perhaps your aggregates at the plant are not being kept in a saturated, surface dry condition and they are not properly compensating with water addition at the time of batching.

I would suggest a ready mix plant audit to see if they are batching correctly.