Historic Reinforced Concrete in Alberta: Analysis and Conservation of Two Structures
Date
2018-09-14
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Abstract
The Brooks Aqueduct and the Greenhill mine tipple structure were built in the turn of the twentieth century in southern Alberta. They were among the first reinforced concrete structures to be built in that region and are considered great engineering and construction achievements for their time. They were both built at a time when there was no standard for the design of reinforced concrete structures in North America and lots of issues about the concrete design and construction, especially from the durability point of view, were still unknown. Both structures had a great impact on the economy of their local regions and now are designated as national and provincial historic sites respectively. Frequent repair and maintenance became necessary from the early stages of operation of Brooks Aqueduct due to design and construction deficiencies. Both structures show significant signs of damage and deterioration and need to be evaluated and properly repaired and maintained.
This research involves evaluation of the two structures through site inspections and laboratory tests on the samples taken from them. The work also involves numerical modelling of the structures to identify areas of possible over stress and find the main causes of damage and deterioration. Several similarities and differences are found between the concrete used in these structures and their deterioration mechanism. The main goal in evaluation and repair of Brooks Aqueduct is to maintain it as a monument and an engineering and construction achievement. In the case of the Greenhill mine tipple structure, two scenarios were studied: adaptive reuse as a restaurant and maintaining the structure as a monument. Results of the analyses show that although there was clear lack of understanding about the behaviour of concrete in the design of these structures, most of the damage and deterioration are non-structural and has happened due to durability issues mainly from exposure to freeze-thaw cycles and corrosion of the reinforcement. Service life analysis of the two structure is also performed based on theoretical models and test results. Recommendations for extending the remaining service life and conservation and retrofitting of the two structures and similar cases are provided based on the results of the tests and analyses. The research identifies common types of problems in historic reinforced concrete structures constructed in Alberta in the early twentieth century and ways to recognise and overcome these problems. The results also emphasize that in evaluation of concrete from the early twentieth century, one has to look for certain problems such as lack of resistance against durability issues (mainly freeze-thaw and carbonation), lack of precision in placement of the reinforcing steel (rebar), lack of rebar splice lengths, lack of proper cover of concrete and lack of proper grading and selection of aggregates.
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Keywords
Reinforced Concrete, Historic Structures, Condition Assessment, Structural Analysis, Finite Element, Durability, Conservation
Citation
Rouhi, A. (2018). Historic Reinforced Concrete in Alberta: Analysis and Conservation of Two Structures (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/33162