A platform for research: civil engineering, architecture and urbanism
A platform for research: civil engineering, architecture and urbanism
For outdoor concrete structures in cold regions, additional air-filled spaces are normally created in concrete to protect concrete structures from frost damage. To ensure frost resistance of concrete, it is of importance to quantitatively evaluate the void structure in hardened concrete. In this thesis, the shape from focus (SFF) method is proposed to capture the depth information of the concrete surface. Based on the performance of focus measure operators and window sizes, the selected operator and window size are used to carry out the SFF analysis of the examined surface. The voids are identified based on the reconstructed depth map. Then the void parameters are determined by an automated analysis. The results demonstrate that the SFF method can be used for automated analysis of the void parameters without contrast enhancement. Contrary to conventional air entraining agents (AEA), superabsorbent polymers (SAP) can be used to engineer the void structure in concrete, which may counteract the strength loss of frost resistant concrete. Also, internal curing provided by SAP may increase the concrete strength. However, the frost behaviours of concrete containing SAP are still not fully understood. In this thesis, the calorimetric freeze-thaw response of liquids in SAP in a cementitious environment is studied. Compared to the bulk exposure liquids, the freezing and melting peaks of liquid in SAP occur at lower temperatures. And the freezing and melting peaks of the liquids in SAP are likely influenced by several factors, e.g., the presence of ice-nucleating agents, the ion concentration in the exposure liquids, the moisture state of SAP, repeated absorption and desorption of SAP, and repeated freezing and thawing. The freezing and melting peak temperatures of liquids in SAP decrease with the decrease of the liquid/SAP ratio in SAP. And a good correlation is observed between the proportion of freezable water in SAP and the freezing and melting peak temperatures. SAP is used to formulate the void structure in cement ...
For outdoor concrete structures in cold regions, additional air-filled spaces are normally created in concrete to protect concrete structures from frost damage. To ensure frost resistance of concrete, it is of importance to quantitatively evaluate the void structure in hardened concrete. In this thesis, the shape from focus (SFF) method is proposed to capture the depth information of the concrete surface. Based on the performance of focus measure operators and window sizes, the selected operator and window size are used to carry out the SFF analysis of the examined surface. The voids are identified based on the reconstructed depth map. Then the void parameters are determined by an automated analysis. The results demonstrate that the SFF method can be used for automated analysis of the void parameters without contrast enhancement. Contrary to conventional air entraining agents (AEA), superabsorbent polymers (SAP) can be used to engineer the void structure in concrete, which may counteract the strength loss of frost resistant concrete. Also, internal curing provided by SAP may increase the concrete strength. However, the frost behaviours of concrete containing SAP are still not fully understood. In this thesis, the calorimetric freeze-thaw response of liquids in SAP in a cementitious environment is studied. Compared to the bulk exposure liquids, the freezing and melting peaks of liquid in SAP occur at lower temperatures. And the freezing and melting peaks of the liquids in SAP are likely influenced by several factors, e.g., the presence of ice-nucleating agents, the ion concentration in the exposure liquids, the moisture state of SAP, repeated absorption and desorption of SAP, and repeated freezing and thawing. The freezing and melting peak temperatures of liquids in SAP decrease with the decrease of the liquid/SAP ratio in SAP. And a good correlation is observed between the proportion of freezable water in SAP and the freezing and melting peak temperatures. SAP is used to formulate the void structure in cement ...
Use of superabsorbent polymers in the production of frost resistant concrete
Li, Gui (author)
2022-01-01
Li , G 2022 , Use of superabsorbent polymers in the production of frost resistant concrete . Technical University of Denmark , Kgs. Lyngby .
Book
Electronic Resource
English
DDC:
690
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