The road works between junctions 47 and 49 will take place from August to December.
Welsh Government agency, Traffic Wales say the project involves essential maintenance work to ensure the longer term resilience of the road network and to avoid any unplanned emergency repairs.
The work will involve the re-waterproofing, resurfacing and replacement of bridge joints to several bridge decks.
It adds that work is taking place during the summer period to minimise the likelihood of delays to the work caused by adverse weather conditions.
During the works between junctions 47 and 49, the traffic management layout will change to accommodate each phase of the scheme with traffic running in contraflow using the hard shoulder from early September until mid-November.
Lower, mandatory speed limits will also be in place to protect drivers and the workforce delivering the scheme.
(Lead image: Google Maps)
