One has to find out what grade of the concrete was specified by the designer and cause of honeycomb in the concrete. One has to conduct NDT for the concrete for the columns which has sound concrete in adjacent locations preferably cast with the same pour and the same tests are conducted at the location after surface preparation is conducted and honeycombed concrete is removed and.or the location nearby the honeycombed concrete but concrete is not observed honeycombed.
The data is analyzed and scrutinized by a competent person. The dept of honeycombed has a critical role to decide the method statement for the repairs to the honeycombed column. Surface honeycombed will be rendered with polymer-modified mortar.
Deep honeycombed for depth exceeding 50mm may be rendered by non-shrink type high-strength micro-concrete. If the concrete grade is very much less than specified, in this case, the columns are jacketed with higher grade of concrete with enlargement of the section by 50 to 100 mm for full height. Competent person will issue you a method statement for treatment to bars, concrete grade shear connectors, and bonding coats.