The building materials giant announced this week that the final hurdle had been cleared with the secretary of state for trade and industry deciding not to refer the deal to the Competition Commission.
The City did not receive news of the deal warmly, with some complaining that RMC should be slimming down, not gaining weight. But the company has ignored the grumbles and gone ahead anyway. Its share price rose 15p to 765p soon after the announcement was made on Tuesday.
The deal, for 206p per share, values Alexander Russell at £59.7m. RMC already owns 22% of its smaller rival.
Meanwhile back at the contractors' ranch, Balfour Beatty was up 7.5% to 221p last week and Carillion rose 6.4%. ROK, formerly known as EBC, continued its strong performance with a 16% rise to 130p.