Concrete Temperature 1

[facca]

It is my belief that the temperature of cement powder has a direct correlation to the temp.of concrete.What should the ideal powder temp. be when it introduced into the concrete.

 

[dirtsqueezer]

I think the temperature of the aggregate/water may have more of an affect on your mix than your cement. Most concrete mixes have on the order of 2-4 times the water and 20 or 30 times the weight of aggregate over cement. I think even if the powder was a source of heat, it could be controlled by regulating the heat of other materials. Up here water is usually the big factor- hot in the winter, cold in the summer. Is there a particular problem with the mix? It's an interesting brain-teaser, because I'm sure there is an ideal temp, but one that can be...gotten around. ] Anyway, two ennies for your spending pleasure. Good luck.

 

[Zambo]

Cement is sometimes delivered dirctly from the factory and can be very hot, this will have an effect on the concrete temperature that may be important if you are trying to control the initial temperature. Ideally cement would be at ambient air temperature.

Zambo

 

[tincan]

The hot load of cement has been blamed for "mud balls" in the mix. A "mud ball" being a large clump of cement that formes when water is added and does not break up and equally disperce thru the mix. The formation of a number of these would reduce the cement content thru the mix and lessen the strength. I have seen "muc balls" the size of small melons in the back of a transit mixer.

 

[Zambo]

I doubt that this is because the cement is hot, certainly I have never seen it. I suggest that the cement is hot because it has come straight from production maybe due to a cement shortage on the market where you are working. Is it possible that this has also encouraged the concrete supplier to use some expired cement as well. It can often be seen that expired cement has hard lumps which may not be broken down in the batching plant.

Zambo

 

[letrab]

The temp of the cement used in the mix does have a direct correlation to the temp of the concrete. For a typical 30 MPa mix 10 deg increase in cement temp will increase concrete temp abt 1.2 degrees.Although water content would be abt half, the effect would be double because of the greater specific heat of water. Cement specific heat =.22 that of water.
Since the aggregates form the bulk of the concrete its temperature also has a greater effect than that of the cement.
I also agree with Zambo that hot cement should not be the reason for lumps forming in the mix.

 

[tincan]

Zambo
Cement plant is only 50+miles from main ready mix plant. It's infrequent, but hot loads happen,

Tincan

 

[facca]

Thanks letrab for the excellent post are the temp you reference metric or imperial.I am trying to improve quality control at the Ready mix plants that supply us and avoid the cost of using ice.

 

[letrab]

Hi facca,
The temp could be any units as long as it is used consistently throughout. We use metric only.

If you send me an e-mail address I will send you a simple spreadsheet to calculate the concrete temp based on the masses and temps of the constituent materials.
We have to use it all the time in the desert to ensure the concrete reach site at an acceptable temp. The calculated results and the actual delivered concrete are normally within 0.5 deg C.

 

[facca]

I would appreciate that greatly email don@faccamcom