January 2010 – South St. Paul, Minn. – What do you get when a structure built 30 years ago is asked to accommodate the handling of a highly corrosive substance? You guessed it… corrosion and deterioration.
Structural engineers from Krech, O’Brien, Mueller and Associates are working with Al Schultz Construction to determine a solution for deterioration in a barge slip located on the shores of the Mississippi River in South St. Paul. The owner of the slip, a national bulk terminal company, has used it to unload salt for some time, and has noticed a developing deterioration in the slip’s concrete cap.

“The top concrete cap is seeing significant degradation, and we believe it’s due to the absorption of spilled sodium chloride and calcium chloride,” said Mike Lisowski, PE, KOMA structural engineer. “The degradation is significantly impacting the cap of the slip, and we want to correct the problem before it requires complete replacement, or before the slip itself becomes a hazard.”

Tests are currently being conducted to confirm the percentage of chloride ions in the concrete and whether or not the ions are the sole contributor to the slips degradation. Upon reviewing the results of the testing, a plan to repair and support the slip will be put forth.

Both sodium chloride and calcium chloride are used in common road salt which – while effective at de-icing roads – is also highly corrosive. “We’ve dealt with the effects of corrosives in the past,” said Lisowski. “Salt, fertilizers and other substances can have a very real effect on the stability of a structure.”