Factors influencing plastic settlement cracks in concrete and the corresponding influence on concrete durability
| dc.contributor.advisor | Combrinck, Riaan | en_ZA |
| dc.contributor.author | Brits, Gabriel | en_ZA |
| dc.contributor.other | Stellenbosch University. Faculty of Engineering. Dept. of Civil Engineering. | en_ZA |
| dc.date.accessioned | 2021-02-18T21:17:17Z | |
| dc.date.accessioned | 2021-04-21T14:32:01Z | |
| dc.date.available | 2021-02-18T21:17:17Z | |
| dc.date.available | 2021-04-21T14:32:01Z | |
| dc.date.issued | 2021-03 | |
| dc.description | Thesis (MEng)--Stellenbosch University, 2021. | en_ZA |
| dc.description.abstract | ENGLISH ABSTRACT: Plastic settlement cracking occurs as a result of differential settlement during the plastic state of concrete. Differential settlement is always caused bya restraining factor, such assteel reinforcement ora varying concrete section depth. Concrete settles due to the influence of gravitational forces. Since plastic settlement cracks occur at the object of restraint, and form from the bottom upwards, it may not be visible at the surface of the concrete, even thoughthey are present below the concrete surface.This has resulted inplastic settlement cracking beingoverlookedas the source or start of durability related issues. Any form of crackingis likely to increase the permeability of the concrete, or act as a weak point that allowother, more severe cracks to form. These cracks permitthe ingress of aggressive agents thataccelerate thedeterioration of the concrete structure. Steel reinforced concretedurabilityis mostly affected by the corrosion of its steel reinforcement; therefore,the quality of the concrete plays a large role in its durability. If the concrete is very permeable and of low quality, it would provideeasy access for aggressive agents to the steel reinforcementwhich may compromise the structural integrity of the structure. This study investigatesthe behaviour of plastic settlement crackingin concreteand the factorsinfluencing it, namely cover depth, re-vibration, viscosity, and plastic shrinkage cracking. Practical measuresweredevelopedto study this behaviour more closelyand durability index tests were performed on the concrete.The crack severity of the plastic settlement cracks wasalsoinvestigated. All these results were comparedto determine the influence of these cracks on the durability of the concrete, depending onthe factor being tested. CT scans werealsotaken to get a visual representationof the cracks present in the concrete. The resultsshow thatasmallerconcrete cover result in more severe plastic settlement cracking. It also indicated that higher strength concrete typically hasless severe plastic settlement cracks. Re-vibration or a lower plastic viscosity does not necessarily decrease the severity of plastic settlement cracks, but it does improve the concrete permeability. Plastic shrinkage cracks are likely to amplify the plastic settlement cracks and make it more severe. It was concluded that plastic settlement crack severity does not directly influence the durabilityparametersof the concrete.The main durability parameters considered for this study was the permeability, sorptivity, porosity and crack severity of the concrete. These factors interacted inconsistently,and it was therefore determined that more durability tests are needed to draw final conclusions. Other aspects also need further investigation, such as the influence of high strength concrete, the influence of higher plastic viscosity, the effect of a different method of re-vibration, and the influence of plastic settlement cracks induced by a varying concrete section depth. | en_ZA |
| dc.description.abstract | AFRIKAANSE OPSOMMING: Geen opsomming beskikbaar | af_ZA |
| dc.description.version | Masters | en_ZA |
| dc.format.extent | 133 pages | en_ZA |
| dc.identifier.uri | http://hdl.handle.net/10019.1/109920 | |
| dc.language.iso | en_ZA | en_ZA |
| dc.publisher | Stellenbosch : Stellenbosch University | en_ZA |
| dc.rights.holder | Stellenbosch University | en_ZA |
| dc.subject | Plastic concrete | en_ZA |
| dc.subject | Concrete -- Cracking | en_ZA |
| dc.subject | Reinforced concrete | en_ZA |
| dc.subject | UCTD | en_ZA |
| dc.subject | Durability of concrete | en_ZA |
| dc.subject | Cracking of concrete | en_ZA |
| dc.title | Factors influencing plastic settlement cracks in concrete and the corresponding influence on concrete durability | en_ZA |
| dc.type | Thesis | en_ZA |