Lafarge recently merged its UK operations with those of Anglo American to create LafargeTarmac, a business employing 5,500 staff at 300 locations. It has dozens of sites around Scotland, ranging from a recycling centre on Glasgow's Bogmoor Road to Dunbar Cement in East Lothian.
Holcim owns Aggregate Industries in the UK. Its Scottish interests are also wide-ranging, including a cement operation at King George V Docks in Glasgow and Glensanda Quarry near Oban.
LafargeHolcim is set to be the world's leading player in cement, concrete and aggregates once the tie-up is completed in the first half of next year.
With the deal set to receive close scrutiny from regulators, the companies plan to offload assets, generating between 10% and 15% of their global earnings.
The tie-up has been presented as a merger of equals, with the new board featuring equal numbers of Lafarge and Holcim directors.