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The deformation properties of concrete with classified Lethabo fly ash
Bibliography: pages 71-74.
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| Other Authors: | |
| Format: | Thesis |
| Language: | English |
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Department of Civil Engineering
2015
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| _version_ | 1867614228870856704 |
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| access_status_str | Open Access |
| author | Mukheibir, Pierre Victor |
| author2 | De Kock, M O |
| author_browse | De Kock, M O Mukheibir, Pierre Victor |
| author_facet | De Kock, M O Mukheibir, Pierre Victor |
| author_sort | Mukheibir, Pierre Victor |
| collection | Thesis |
| description | Bibliography: pages 71-74. |
| format | Thesis |
| id | oai:open.uct.ac.za:11427/15944 |
| institution | University of Cape Town (South Africa) |
| language | eng |
| last_indexed | 2026-06-10T12:48:43.029Z |
| license_str | Not specified — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UCTD — University of Cape Town Open Access Repository |
| publishDate | 2015 |
| publishDateRange | 2015 |
| publishDateSort | 2015 |
| publisher | Department of Civil Engineering |
| publisherStr | Department of Civil Engineering |
| record_format | dspace |
| source_str | UCTD — University of Cape Town Open Access Repository |
| spelling | oai:open.uct.ac.za:11427/15944 The deformation properties of concrete with classified Lethabo fly ash Mukheibir, Pierre Victor De Kock, M O Civil Engineering Concrete Bibliography: pages 71-74. It has become necessary to determine the magnitude of creep, shrinkage, elastic and thermal deformations of concrete as these characteristics determine the loss of prestressing in prestressed concrete and affect the deflections with time of large concrete sections. Much of the literature available on this topic has conflicting conclusions. In this research, the effect of fly ash was first investigated with regard to general concrete properties such as bleeding, early set, workability, mortar excess and compressive strength. Classified Lethabo fly ash and local Western Cape materials were used for this work. With the increase in the percentage fly ash present in the concrete mix, the water requirement was reduced in order to get the same workability. This characteristic reduced the amount of water available for bleeding. For a given C/W ratio the inclusion of fly ash in a concrete mix had no effect on the mortar excess. The early setting time was retarded for mixes with increasing percentages of fly ash. Higher cementitious material to water ratios were required for concrete with classified Lethabo fly ash than Ordinary Portland Cement mixes, to obtain the same 28 day compressive strength. The fly ash mixes had higher strength developments with time i.e. they have lower early strengths and higher long term strengths than OPC mixes for the same 28 day compressive strengths. Having developed a wide range of concrete mixes, the main investigation was done on specific deformation properties of concrete such as the elasticity, shrinkage, creep and thermal movement. The effect of different wet curing durations and testing ages on these properties were investigated. The elastic modulus was determined by both static and dynamic test methods. A relationship was established between the two methods to estimate the static modulus from the dynamic modulus, which was quicker to perform. In this thesis, the elastic modulus was not affected by the presence of fly ash. The elastic properties of the fly ash mixes was found to be similar to that of the OPC mixes of the same compressive strength. Similarly, the drying shrinkage and thermal movement were not affected noticeably by the presence of fly ash. The volume of aggregate was not a variable as it did not change when fly ash was added to the mix. An attempt was made to develop a test to determine the plastic shrinkage of an unrestrained sample. The effect of fly ash on the plastic shrinkage was not investigated fully. For the creep of concrete, it was established that mixes containing fly ash have lower creep factors than OPC concretes, although no clear trends were apparent for increasing percentages of fly ash. The effect of fly ash in pump mixes was also investigated and the same trends were apparent, although in general, the pump mixes had higher creep factors than the normal mixes. The curing of concrete is critical if good quality concrete is to be obtained. For all deformation properties, the longer a specimen was wet cured, the lower were the deformations. With longer wet curing, a larger volume of hydrated gel developed which gave higher compressive strengths and more rigidity within the matrix. The conclusion reached in this thesis was that the presence of classified Lethabo fly ash did not noticeably affect the deformation properties of the concrete for equivalent compressive strengths. Where some effects were noticed, the fly ash concretes displayed somewhat lower deformations. 2015-12-28T05:59:29Z 2015-12-28T05:59:29Z 1990 Master Thesis Masters MSc http://hdl.handle.net/11427/15944 eng application/pdf Department of Civil Engineering Faculty of Engineering and the Built Environment University of Cape Town |
| spellingShingle | Civil Engineering Concrete Mukheibir, Pierre Victor The deformation properties of concrete with classified Lethabo fly ash |
| thesis_degree_str | Master's |
| title | The deformation properties of concrete with classified Lethabo fly ash |
| title_full | The deformation properties of concrete with classified Lethabo fly ash |
| title_fullStr | The deformation properties of concrete with classified Lethabo fly ash |
| title_full_unstemmed | The deformation properties of concrete with classified Lethabo fly ash |
| title_short | The deformation properties of concrete with classified Lethabo fly ash |
| title_sort | deformation properties of concrete with classified lethabo fly ash |
| topic | Civil Engineering Concrete |
| url | http://hdl.handle.net/11427/15944 |
| work_keys_str_mv | AT mukheibirpierrevictor thedeformationpropertiesofconcretewithclassifiedlethaboflyash AT mukheibirpierrevictor deformationpropertiesofconcretewithclassifiedlethaboflyash |