We decided that it was too icy in the freezing temperatures we had over night (well below zero all night) and the concrete has lots of patches of frozen water all over the place.
It would have been too risky to be playing around with pieces of steel framework that weighs hundreds of kilograms, trying to hoist them up etc.
So after lunch, after waiting to see if the ice will melt, we decided that the day was lost to the weather.
The forecast says that the next 2 days could be warmer with lots of sunshine so we keep our fingers crossed and we can resume progress.