Influence of substrate moisture preparation on concrete overlay bond strength

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dc.contributor.advisorBeushausen, Hans-Dieteren_ZA
dc.contributor.advisorMoyo, Pilateen_ZA
dc.contributor.authorTalotti, Marcoen_ZA
dc.date.accessioned2014-11-05T03:33:47Z
dc.date.available2014-11-05T03:33:47Z
dc.date.issued2014en_ZA
dc.descriptionIncludes bibliographical references.en_ZA
dc.description.abstractA considerable amount of progress has been made over the years in understanding the fundamentals of concrete composition and performance in both safe and harsh environments. Nevertheless, premature concrete deterioration remains a concern and is often experienced either due to poor workmanship or design. The bonded concrete overlay technique has become a popular method in repairing these deteriorated concrete structures, as it has a simplistic application procedure and can be applied to a number of different scenarios. This technique involves the removal of the distressed layer of concrete (substrate), followed by the application of a fresh, new layer of concrete (overlay). One of the fundamentals behind bonded concrete overlays is the bond between the existing and new concrete layer. Sufficient bond strength is a prerequisite for the durability and serviceability of a repaired concrete structure. Factors which have been considered most important for achieving a good bond between the substrate and overlay are cleanliness and preparation of the substrate, together with overlay compaction and composition. However, the impact of substrate moisture condition on the bond strength of a repaired member has not been fully investigated and still raises many debates amongst engineers. Current best practice suggests that a concrete substrate which is preconditioned to a saturated surface dry state prior to overlay application will achieve higher bond strengths. This investigation provides insight into the aforementioned through both literature research and practical experiments performed. In this investigation the effects of moisture preparation on bond strength were tested on three different substrate concretes, together with the application of four overlays. The substrates varied according to strength grade (50, 30 and 25 MPa), whereas the overlays varied in both strength (40 and 25 MPa) and workability (30 and 120 mm slump). The accompanied bond strength was established through interface shear testing. All substrates of the repaired specimens were subjected to a constant surface roughness and equally aged to prevent any differential shrinkage which may falsify bond strength readings. The bond strength results were plotted, statistically evaluated and compared with existing literature.en_ZA
dc.identifier.apacitationTalotti, M. (2014). <i>Influence of substrate moisture preparation on concrete overlay bond strength</i>. (Thesis). University of Cape Town ,Faculty of Engineering & the Built Environment ,Department of Civil Engineering. Retrieved from http://hdl.handle.net/11427/9080en_ZA
dc.identifier.chicagocitationTalotti, Marco. <i>"Influence of substrate moisture preparation on concrete overlay bond strength."</i> Thesis., University of Cape Town ,Faculty of Engineering & the Built Environment ,Department of Civil Engineering, 2014. http://hdl.handle.net/11427/9080en_ZA
dc.identifier.citationTalotti, M. 2014. Influence of substrate moisture preparation on concrete overlay bond strength. University of Cape Town.en_ZA
dc.identifier.ris TY - Thesis / Dissertation AU - Talotti, Marco AB - A considerable amount of progress has been made over the years in understanding the fundamentals of concrete composition and performance in both safe and harsh environments. Nevertheless, premature concrete deterioration remains a concern and is often experienced either due to poor workmanship or design. The bonded concrete overlay technique has become a popular method in repairing these deteriorated concrete structures, as it has a simplistic application procedure and can be applied to a number of different scenarios. This technique involves the removal of the distressed layer of concrete (substrate), followed by the application of a fresh, new layer of concrete (overlay). One of the fundamentals behind bonded concrete overlays is the bond between the existing and new concrete layer. Sufficient bond strength is a prerequisite for the durability and serviceability of a repaired concrete structure. Factors which have been considered most important for achieving a good bond between the substrate and overlay are cleanliness and preparation of the substrate, together with overlay compaction and composition. However, the impact of substrate moisture condition on the bond strength of a repaired member has not been fully investigated and still raises many debates amongst engineers. Current best practice suggests that a concrete substrate which is preconditioned to a saturated surface dry state prior to overlay application will achieve higher bond strengths. This investigation provides insight into the aforementioned through both literature research and practical experiments performed. In this investigation the effects of moisture preparation on bond strength were tested on three different substrate concretes, together with the application of four overlays. The substrates varied according to strength grade (50, 30 and 25 MPa), whereas the overlays varied in both strength (40 and 25 MPa) and workability (30 and 120 mm slump). The accompanied bond strength was established through interface shear testing. All substrates of the repaired specimens were subjected to a constant surface roughness and equally aged to prevent any differential shrinkage which may falsify bond strength readings. The bond strength results were plotted, statistically evaluated and compared with existing literature. DA - 2014 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 2014 T1 - Influence of substrate moisture preparation on concrete overlay bond strength TI - Influence of substrate moisture preparation on concrete overlay bond strength UR - http://hdl.handle.net/11427/9080 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/9080
dc.identifier.vancouvercitationTalotti M. Influence of substrate moisture preparation on concrete overlay bond strength. [Thesis]. University of Cape Town ,Faculty of Engineering & the Built Environment ,Department of Civil Engineering, 2014 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/9080en_ZA
dc.language.isoengen_ZA
dc.publisher.departmentDepartment of Civil Engineeringen_ZA
dc.publisher.facultyFaculty of Engineering and the Built Environment
dc.publisher.institutionUniversity of Cape Town
dc.titleInfluence of substrate moisture preparation on concrete overlay bond strengthen_ZA
dc.typeMaster Thesis
dc.type.qualificationlevelMasters
dc.type.qualificationnameMScen_ZA
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceThesisen_ZA
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