Demand is intense for the sale of Boral Ltd.'s fly ash unit, which is to be worth more than billion

Australian building materials group Boral Ltd. the sale of the fly ash unit is attracting interest from companies including Holcim Ltd. the second-largest cement maker worldwide.

Germany-based HeidelbergCement AG said it was also examining a potential acquisition of the North American-focused business , which could be worth more than $ 1 billion, asking not to be identified while discussing classified information.

The sale process has also attracted private equity firms, the people said. Negotiations are ongoing and there is no certainty that the companies will proceed with formal proposals, according to the public.