Condition and Durability of Segmental Concrete Block Retaining Walls Along Roadways in Minnesota

This research project assesses the nature and extent of premature deterioration of segmental concrete block retaining walls (SCBRWs) along roadways in the Minneapolis-St. Paul area. Researchers conducted a two-stage condition survey on 104 SCBRWs. The first stage, a general distress survey, focused on determining the type, severity, and extent of distresses present. The second stage, a peak winter survey, assessed the extent of snow/ice cover and exposure to winter sun. According to research results, only 7 percent of the SCBRWs surveyed were in poor or very poor condition. But researchers observed many distress types in 50 percent or more of the walls surveyed, including freeze-thaw damage, scaling, manufacturing flaws, and efflorescence. Freeze-thaw damage and scaling were most highly associated with decreases in overall wall condition. Efflorescence and freeze-thaw damage were found to be at least partly dependent upon SCBRW age and block manufacturer. Durability problems appear to be directly related to the lack of durability of the block units, which suggests problems with the use of inadequate mix designs, non-durable aggregate, and/or inadequate curing procedures. The report includes recommendations to address possible deficiencies in manufacturing processes and quality.