摘要: |
In the past several decades, reinforced concrete structures have deteriorated similarly by chemical attack, especially chloride attack. For highway bridges, this phenomenon becomes more severe since bridges are exposed to extreme environmental conditions, such as snow and ice. In an effort to better protect the bridge decks and reduce maintenance costs, State Departments of Transportation (DOT) apply waterproofing membranes (WPMs) to the bridge decks. The use of WPMs was investigated by the Colorado Department of Transportation (CDOT) to analyze the performance of four products as an effective protection system: Polyguard, Protecto Wrap, Bridge Preservation鈩? and Sikadur. Each WPM was installed on Bridge F-17-YB and monitored for approximately two years. The performance of each WPM was evaluated for bond strength, resistance to chloride intrusion, freeze-thaw resistance, and cost analysis. Pull-off testing showed that all the WPMs have higher bond-strength than the control section, especially the constructed-in-place WPMs. Chloride penetration tests included testing the chloride concentration profiles of specimens extracted from the decks and from ponded specimens. The short-term results indicate that all four WPM systems can effectively control the intrusion of moisture, but not the migration of the chloride ions into the concrete deck. Among the materials tested, the Bridge Preservation鈩?product provided the best performance. At last, a simplified model has been developed to predict the long-term performance of WPMs. |