If you're pouring buckets down the col formwork, you might get that effect.
The rebar acts like a sieve, catching and slowing the large aggregates. So you get a thin layer of weak cement landing, and then a layer of gravel on top. Next bucket a similar thing happens, and you end up with thin...
Khinz,
On top of everything else, you need to hold the contractor to the specification of the stirrups.
Those overlapping corners need to be bent 'in' as shown on your drawing - it stops them popping open if the frame twists due to any reason (eg earthquake)
(also, comparing the drawing and...
