[Benito]

Today.

 

[androiduk]

I think I saw that when I walked by yesterday. They kind of look like spider veins on a human. I've seen that before.

 

[p5connex]

I am not sure what you saw exactly, but it does sound a lot like craze cracks. These are noticeable when the formwork is removed as the concrete has set, but then gets wet, in this case rain/snow falling on it. Its appearance looks like dozens of hairline cracks racing around the surface of the concrete. They are superficial and mostly will have no consequence on the performance of the concrete. This can be a symptom of curing too fast, or other issues ie: water content in mixture etc. Generally, as concrete cures, the chemical processes/reactions taking place within it, drive the water inside the mixture toward the surface, where it evaporates and in many cases it drying faster than other areas, often resulting in these types of 'hairline cracks' you may have seen.

Or it could be that the building is doomed!

 

[jibsta]

Well these are massive thick pours, meaning they generate tons of heat and evaporate water.

 

[Full Metal Junkie]

Wet concrete reveals a lot of neat structural details. Case in point, this is what CN Tower looks like when wet

 

[p5connex]

Well these are massive thick pours, meaning they generate tons of heat and evaporate water.

Yes, exactly! If you have ever poured concrete yourself, you can feel the heat the concrete emits as it cures. Not to mention, given the size of these columns, they will be curing (gaining in compressive strength) for months potentially. I recall a project where the concrete on 1 section of a slab pour, took 45 days to reach its minimum required bearing capacity.

 

[vinny_the_hack]

Looking at the recent photos, I am taken aback by the amount of complexity at the site.

 

[interchange42]

Looking at the recent photos, I am taken aback by the amount of complexity at the site.

One would think a 308 metre-tall building with no central elevator core going all the way to the foundations would be more of a walk in the park.

42

 

[BloorMan]

How are you able to see a hairline crack? Are you able to get in there up close?

Here are 2 pictures I took today. Not sure if it's anything to worry about but most certainly, there are cracks.

 

[The Preservationist]

First photo a bit sub par but I've seen surface cracking or crazing at this level before. In one much more extreme case in northern Quebec during a winter pour it was so bad that they chipped the surface down, chemi bonded and patched up. I'm a Mechanical Systems design and install guy by trade so maybe someone else knows more about this.
Second photo looks like you've possibly got cracking through the entire cross section of the column. I did ask a question on this form concerning the amount of rebar versus concrete with thermal expansion of the rebar about a month ago. I suspected that quantity of rebar would cause cracking. The column will be in high compression once loaded so generally horizontal cracking shouldn't be an issue but again I'm getting a little out of my working area. Any thoughts?

 

[ProjectEnd]

Here are 2 pictures I took today. Not sure if it's anything to worry about but most certainly, there are cracks.

Those 'cracks' are completely normal for something like this. Nothing to get worked up over.

 

[jibsta]

I would say over watered concrete for a complex thick pour, nothing that would be a major issue but they can do better

 

[vinny_the_hack]

I would say over watered concrete for a complex thick pour, nothing that would be a major issue but they can do better

Maybe a forum member who lives or works in the area can try to snap some photos of a different column to see if, in fact, they did do better.

 

[Hoppysquirrel]

 

[Benito]

Today.