| Author: | Fong, Ming-sum |
| Title: | Hydration heat in mass concrete |
| Degree: | M.Sc. |
| Year: | 2000 |
| Subject: | Concrete -- Thermal properties Concrete -- Cracking Heat of hydration Thermal stresses Concrete construction Hong Kong Polytechnic University -- Dissertations |
| Department: | Multi-disciplinary Studies Department of Civil and Structural Engineering |
| Pages: | xi, 108 leaves : ill. ; 30 cm |
| Language: | English |
| Abstract: | This thesis presents a thorough study on the methods to control or lower the adverse effects due to heat of hydration at early ages of concrete construction. Detailed investigation was carried out on the concrete hydration heat parameters and two most effective concrete hydration heat property measuring devices, i.e. adiabatic calorimeter and rigid cracking frame. The following hydration heat control methods also had been studied: (I) pre-cooling fresh concrete, (II) post-cooling fresh concrete, (Ill) concrete ingredient manipulation, (IV) replacing part of cement by pozzolanic materials, (V) construction sequence, lift height and pour size control, (VI) proper curing of mass concrete, (VII) type 'U' expansive agent (UEA). Each control method was critically evaluated. Concrete is preferably to be cooled, particularly in mass concrete construction. Lower water and cement contents for a given strength and slump can offset adverse effects due to temperature rise in mass concrete caused by heat of hydration of the cement. Thermal contraction of concrete is reduced by the lower cement content and by the lower water content of concrete. Thereafter, five case studies, which adopted the combination of the abovementioned hydration heat control methods, were analyzed and compared. By using field measurement data and computer analysis, the risk of cracking was evaluated. Finally, effective temperature control procedures relevant to Hong Kong situations were proposed. |
| Rights: | All rights reserved |
| Access: | restricted access |
Files in This Item:
| File | Description | Size | Format | |
|---|---|---|---|---|
| b15179734.pdf | For All Users (off-campus access for PolyU Staff & Students only) | 3.42 MB | Adobe PDF | View/Open |
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