BRUSSELS--Irish building-materials company CRH PLC (CRH.DB) secured European Union approval for its 6.5 billion euro ($6.98 billion) purchase of assets from Lafarge SA (LG.FR) and Holcim Ltd. (HOLN.VX), clearing a key hurdle toward the completion of the two cement companies' $40 billion merger.

The European Commission, the bloc's top antitrust regulator, said Friday that the asset sale didn't raise concerns because CRH would continue to face sufficiently strong competition in markets where its activities overlapped with the divested businesses.

The sale of the cement assets in Europe, Canada and elsewhere is a precondition of winning antitrust approval of the pending merger between France's Lafarge and Switzerland's Holcim.

The two companies announced their merger in April last year, and said they hoped to close the deal in the first half of 2015. To address competition concerns, the companies agreed to sell assets that generate roughly EUR5 billion in annual revenue.

CRH announced in February that it would purchase the assets. The Irish company had been vying for them with a private-equity consortium including Blackstone Group LP, Cinven and Canada Pension Plan Investment Board, people familiar with the matter said at the time.

Shayndi Raice in London contributed to this article.

Write to Tom Fairless at tom.fairless@wsj.com

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