Students returning for the summer semester may find the King Memorial Commons concrete replaced at no expense to NIU.

Because the crumbling concrete was found to be the fault of the contractor, the contracting company will repair the concrete at its own expense from May 13 until June 15, said Eddie Williams, vice-president for Finance and Planning.

Perkins and Will, the project architects, as well the Capital Development Board have recommended that Alliance Contractors replace the cracked concrete at their expense.

Recent concrete test results concur with previous findings, said Eddie Williams. Previously, it was speculated that the damage was the result of a lack of air in the cement, which was confirmed in the most recent tests of April 12.

Core concrete samples were sent to an independent laboratory to determine why the crumbling occurred, Williams said at the Board of Regents’ Finance and Facilities committee meeting April 17.

Williams said the concrete “spalling” was caused by a lack of air, which should be captured in the concrete during pouring and setting, allowing the concrete to expand and retract during freeze and thaw cycles.

“If there is not sufficient air entrapped in the concrete, the freeze and thaw cycles will cause it to spall,” Williams said. “The first results from the laboratory concluded that there was not a sufficient air entrapment.”

Patricia Perkins, administration assistant of Finance and Planning, said several factors can cause a lack of air, including improper mixture, added water and increased transportation time.

The tests were funded by the Capital Development Board in Springfield and not by NIU, Perkins said.

Perkins said the contractor, Alliance Contractors in Woodstock, Ill., is responsible for laying concrete that meets specific standards.

Chuck Ruth of Alliance Contractors declined to comment on the situation.

“There appears to be a general problem with projects throughout the DeKalb area, all of which used the same concrete supplier,” according to the president’s report released last week.

Perkins said the supplier was Johnson Concrete, 1302 E. Lincoln Hwy. Owner Steve Larson could not be reached for comment Monday.

Perkins said her office is anxious to have the project finished because they are proud of the significance of the memorial to Dr. King.