With investments on hold in much of the world due to an uncertain global economic outlook, makers of building materials are focused on cutting costs and boosting efficiency.

This has triggered a consolidation wave that has seen Lafarge and Holcim combine to create the world's biggest cement maker. HeidelbergCement responded in July when it agreed to buy control of Italcementi in a deal that valued its smaller Italian rival at 6.7 billion euros (4.74 billion pounds).

HeidelbergCement said the acquisition was on track, increasing its synergy target to 300 million ($326 million) euros a year from 175 million previously.

"We assume that investors have finally realized the clever acquisition move ... with more realistic synergies target and which we expect to have a better chance to create value than merging two completely different cultures," Baader Bank analyst Patrick Appenzeller wrote to clients, keeping a "buy" rating.

Shares in HeidelbergCement gained 3.5 percent as the second-biggest gainers in Germany's blue-chip index. They have remained flat since the Italcementi acquisition was announced, compared with a 14 percent drop of LafargeHolcim over the same period.

Traders said the raised synergy target offset a lower sales outlook for 2015, which the group blamed on weakening cement demand in Eastern Europe, Central Asia and Russia, where investments fell.

HeidelbergCement said it now expected moderate to significant growth in sales in 2015. It previously expected sales to rise significantly.

"From our perspective, the weaker development of sales volumes compared with the previous quarters is temporary in nature," Chief Executive Bernd Scheifele said in a statement.

The company -- which makes cement, concrete, building products and is the world's biggest producer of sand, gravel and crushed-rock aggregates -- also reported third-quarter core earnings of 865 million euros, slightly lower than expected.

(Editing by Georgina Prodhan and Keith Weir)

By Christoph Steitz

Stocks treated in this article : Italcementi SpA, HeidelbergCement AG, Lafargeholcim Ltd