Alfred McAlpine will officially become part of Carillion on 12 February if the £572m takeover proceeds as planned.
In a statement Carillion said McAlpine’s shares would be delisted on that day, followed by the issue of fresh Carillion shares.
The move will follow extraordinary general meetings at Carillion on 14 January and Alfred McAlpine on 21 January.
Although no announcements have been made about the make-up of the board, City sources said the deal spelled the end for Ian Grice, chief executive of Alfred McAlpine. He has been blamed for weak profit figures.
One City source also speculated that Matt Swan, managing director of project services at Alfred McAlpine, would leave, after the appointment of David Hurcomb as Carillion’s head of building and private finance operations last month.