In pre-GST era, as per Notification No.24/12-ST dated 6.6.12
(a) “original works” means-
(i) all new constructions;
(ii) all types of additions and alterations to abandoned or damaged structures on land that are required to make them workable;
(iii) erection, commissioning or installation of plant, machinery or equipment or structures, whether pre-fabricated or otherwise.
In pre-GST era your activity was covered under this notification.
Now definition of 'works contract ' has changed. More emphasis is laid on construction of original works. Even then in view of the language of the above Notification Serial No.V(e), you can get the benefit of word, "Infrastructure" for GST rate of 12 %. It is stretching. The issue is not litigation-free. Better option is to seek clarification from GST Council.
You must make efforts. Chances are bright.