Service Life Assessment and Improvement of Concrete Infrastructure
|
|
Freeze-Thaw Durability and Modeling of Concrete InfrastructureIn many regions of the US such as the Midwestern region, the Northeastern region, and the Mountain region, concrete infrastructure is exposed to freezing and thawing. In these regions, a large portion of concrete infrastructure (such as concrete pavements or concrete bridges) experiences damage and degradation well before the expected service life is reached. This is increasingly problematic as transportation agencies are requesting pavements and bridges with a longer initial service life (40-50 years or more). This research attempts to understand a variety of complex damage mechanisms that occur during freezing and thawing using advanced experimental techniques (e.g., electrical measurement, stress wave technique, multi-scale experimental characterization, image processing, and thermal analysis techniques) and numerical modeling. The results of this research provide an advanced understanding of freezing and thawing problems and help to find ways to mitigate the damage and increase the service life of concrete infrastructure exposed to freezing and thawing.
Read More |
|
|
Chemical Degradation in Concrete Infrastructure due to Salt ExposureMany concrete infrastructure systems (e.g., pavements, bridges, tunnels, and underground structures) are in exposure to different types of salts. Salts can interact with cementitious materials and can cause damage and degradation to the concrete infrastructure. This research shows that chloride based salts can severely deteriorate concrete with or without thermal cycling. The deterioration is mainly due to chemical reactions, addition of osmotic pressure to ice formation, and crystallization pressure. Advanced techniques (e.g., stress wave techniques, thermal analysis, microstructural characterization, chemical analysis, and physio-chemical characterization) are used to evaluate and monitor the performance, response, and durability of concrete due to chemical distresses caused by salt exposure and to increase the service life of concrete infrastructure expose to salts.
Read More |
|
|
Transport of Fluids and Ionic Species in Concrete InfrastructureEvery year, a considerable amount of national budgets are dedicated to repairing, reconstruction, and rehabilitation of the existing infrastructure due to corrosion of reinforcing steel. Studies show that the annual direct losses caused by corrosion of reinforcement in the US highway bridges are estimated at 276 billion dollars, approximately 3.1% of the nation’s Gross Domestic Product (GDP). This research uses advanced transport testing of fluid/gas/ion in concrete (e.g., absorption, chloride migration testing, electrical resistivity measurement, gas diffusivity, gas permeability, and x-ray fluorescence) to understand the migration of ions, fluids, and gases to cause corrosion, freezing/thawing damage, and chemical degradation in concrete infrastructure. The results of this research can be used to predict and increase the service life of concrete infrastructure exposed to corrosion, carbonation, freezing/thawing, and/or chemical degradation.
Read More |
