Why doesn't the floor concrete burn?

[anders07]

I have bought Kiilto Floorfiller which is supposed to be "walkable" after 2 hours and cure in 2 days according to the instructions. I have mixed 6 bags according to the instructions and mixed well (at least I think so).

It has now been three days (just over) and I can still make marks with my thumb in it.

The bucket I mixed in was new. Some old dried residues of regular concrete on the mixer and municipal water from the tap and primed concrete slab underneath...

Can "old" concrete behave like this or did I miss something?
(purchased at the local builders' merchant where I suspect the bags have been lying for a long time)

 

[AG A]

There is only one thing I can think of. There must be something wrong with the cement, maybe it's old. I know several people who have had problems with concrete that doesn't set, even though they have tried mixing it in several ways.
Cement/cement mortar can normally be mixed in almost any way, and it will still set. However, with varying strength.

 

[myrstack]

Have had old fall-building mortar that hasn't set as it should (LIP245) due to age, so something definitely happens over time with special cement

 

[Isakare]

Had a bag of quick-setting cement 15 min that had been unopened for 2 years, nothing happened, had to scrape it off again, read on the bag "Storage time 6 months"

 

[largab]

Unfortunately, one must always check the best-before date on the bags. There are many sales outlets that do not keep track of this.

 

[oceanis]

Had similar issues with Weber's leveling compound a couple of years ago. It turned out that the sacks delivered had expired. After discussions directly with Weber, they confirmed that such things could happen with old sacks but that the process normally continued anyway. We solved it by increasing the heat in the room, which got the process going, and it was most noticeable in the parts of the floor that were coldest and near exits and walls.

 

[anders07]

OK, thanks for the response. Unfortunately, I don't have the bags anymore to check, but they were really dusty and were on the side of everything else in an "outdoor shed" at the construction market. It's probably not below freezing in the shed, but it's cold during the winters, so I suspect it might be age. Now after a little over four days, it's starting to harden, but I can still scrape the surface with, for example, a screwdriver...

 

[Eld]

Raise the temperature in the space.

 

[anders07]

Raise the temperature in the space.

Well, I set up a small 2kW construction heater and wrapped it in plastic last night, and now it's rock solid. Last time I open a bag of concrete without checking the date marking!