I am working in a pvt ltd. Construction comp. Will this be considered as a work exp. In top iims?

Yes it will be taken as work experience in every IIM or any other b-school. Point is to make your work experience count your company should be legally registered then whether it is small or big company it does not matter. And you need to have a certificate/leaving letter on the official paper of company showing the work duration in which you have worked in the company.

During the interview process every college will be going through all the documents and if you don't have a valid work experience proof then you won't be given the perks of work experience which you get in your selection process. With a valid work experience of more than 6 months you get additional marks of around 5% in your aggregate score which is used to make up a merit list.

So make sure that your company is legally registered and you have valid proof of your work experience then definitely you can enjoy the perks of work experience in every IIM.