Heat production of massive concrete pylon cast in warm climate 2

[hmlilja]

I'm involved with pylon-design for cable stayed bridge in warm climate, planning to use C50 (fck=50MPa) concrete (C40 in general, C50 in most critical cross sections), cross section is ~3*3,5 meters with 1,5m hole inside. What do you think, is the temperature production a problem, outside temp can reach up to 35-40C, sorry not familiar with Farenheit ;-)
Any tips for precautions to avoid cracks due to temp production? How to predict/control the temp production? Anything in internet concerning the problem?

Heikki

 

[Ron]

Since you have the capability to dissipate heat in the interior of the shaft through the 1.5m hole, I would not worry too much about the heat build-up as compared to true "mass" concrete. I would follow ACI recommendations for "Hot Weather Concreting".

 

[JAE]

Agree with Ron. Also: try ACI 207.4R-93 for good recommendations on mass concrete and the heat/cracking problems.

 

[hmlilja]

Thank you guys, this forum seems to be working well!

 

[hmlilja]

Hello again,

Agree with you both, because of the shaft the heat production is well controlled when considering one casting section itself. But how about the previous casting section that has already cooled down, any worries that cracks might appear right above the casting joint (after latest casting section cools to the same temperature as previous one?). I've heard about some problems with similar climbing casting system in this climate with concrete C50 (cross section of pylon was bit larger though). I don't have ACI 'Hot weather concreting' or ACI 207.4R-93 with me right now (I'm already here behind God's back, it takes a while to get those), any change of finding those from internet?

Cheers, Heikki

 

[Jim6758]

In addition to the above, you could use a high quality fly ash as a component in your mix and don't let the Contractor get in a hurry to strip the forms.

 

[farhat]

I am working on the thermal gradient of concrte results from the ambient temperature which is not more that 50 C. I am really seeking an answer for the effect of high ambient temperature on the bond between concrete beams and repair materials.
In case the concrete beam is casted in hot environemnt, there will be a thermal gradient occures in mid day between the surface and extends toward the repair system if the beam is repaired on the tension phase.

thatnk you
farhat