FRANKFURT — If the past is any guide, European Union leaders will leave their summit meeting this week waving promises to weave the eurozone more tightly together. They are likely to back a plan to finance infrastructure projects in stricken countries.

But unless the usual expressions of resolve are bolstered by concrete action or at least a binding timetable, financial markets are likely to continue to penalize Spain and other troubled countries by pushing up their borrowing costs to levels that will eventually prove unaffordable.

‘‘We know by experience that recent summits have generated expectations that were not met by decisions,’’ Joaquin Almunia, vice president of the European Commission, said last week.

The ideal outcome from the meeting in Brussels on Thursday and Friday, as a rising chorus of central bankers and foreign leaders has made clear, is deliberate movement toward a eurozone in which countries would backstop one another’s banks and bonds, while policing one another’s spending.

On Sunday, the Bank for International Settlements was the latest to urge eurozone leaders to establish a banking union.

Wolfgang Schauble, the German finance minister who is known as an advocate of a stronger European central government, said in an interview published Sunday that Germany may need to hold a referendum on a new constitution within several years, to make it easier for the country to cede budgetary authority.

A meeting of leaders of the four largest countries in Rome on Friday suggested what might be expected from the full meeting this week. The leaders of Germany, France, Italy, and Spain agreed to a $163 billion growth pact, which mostly redirects existing funds. It would also create so-called project bonds, with the eurozone providing credit to private companies for infrastructure projects and job creation.

While helpful, the plan, expected to be formalized at the summit, does not address the underlying weaknesses of the eurozone.