Any Graduates here who know about Post-tensioning in construction? I need help?

Post-tensioning (PT) is a technique for constructing very efficient concrete bridges and floor slabs... basically you cast steel cables into the concrete inside tubes which run from one end to the other, then after (the "post-" bit) the concrete has set you use a jack to stretch the cables slightly (the "tensioning"). Once the cables have been stretched you lock them off against the edge of the slab, this means a compressive force is in the concrete which prevents it from cracking which improves its performance. It is very similar to pre-stressed concrete and a lot of things on the internet about PT also refer to pre-stressed. Although the principles are quite simple there are a lot of subtleties to it which have to be taken into account when actually designing something. I am working on some buildings with PT floor slabs at the moment.

It has been around for a while and is very routine in other countries e.g. Australia, but is still seen as quite a niche thing to do in the UK. I'm not sure why this is, maybe because there were some high profile collapses of PT structures decades ago which put people off it and it hasn't quite recovered. It's getting more popular though (I think) for buildings, at least, the workmanship problems which it used to cause problems have now been resolved, also clients like it as it means less concrete, faster construction and longer spans which mean more flexible spaces.

TBH assuming you have studied whatever engineering degree is relevant to the role you're applying for, I'm surprised you haven't heard of it!