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Testing plastic shrinkage and cracking in concrete with an improved digital image correlation method
Thesis (MEng)--Stellenbosch University, 2023.
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| Format: | Thesis |
| Language: | en_ZA en_ZA |
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Stellenbosch : Stellenbosch University,
2023
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| _version_ | 1867614079133155328 |
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| access_status_str | Open Access |
| author | Fenton, Craig Taylor |
| author2 | Combrinck, Riaan |
| author_browse | Combrinck, Riaan Fenton, Craig Taylor |
| author_facet | Combrinck, Riaan Fenton, Craig Taylor |
| author_sort | Fenton, Craig Taylor |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University, |
| description | Thesis (MEng)--Stellenbosch University, 2023. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/127224 |
| institution | Stellenbosch University (South Africa) |
| language | en_ZA en_ZA |
| last_indexed | 2026-06-10T12:46:20.037Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2023 |
| publishDateRange | 2023 |
| publishDateSort | 2023 |
| publisher | Stellenbosch : Stellenbosch University, |
| publisherStr | Stellenbosch : Stellenbosch University, |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/127224 Testing plastic shrinkage and cracking in concrete with an improved digital image correlation method Fenton, Craig Taylor Combrinck, Riaan Stellenbosch University. Faculty of Engineering. Dept. of Civil Engineering. Digital image correlation; plastic shrinkage; plastic shrinkage cracking; plastic settlement; concrete shrinkage Digital image correlation; Concrete -- Expansion and contraction Plastics -- Additives Plastics at high pressures Resin concrete Thesis (MEng)--Stellenbosch University, 2023. ENGLISH ABSTRACT: Plastic shrinkage cracking is a well-known issue in concrete elements, as it is linked to many durability issues. Despite plastic shrinkage being a well-researched topic, the methods for its measurement still have limitations. Traditional testing methods for plastic shrinkage and plastic shrinkage cracking only consider either a single point on or in a concrete specimen or the visible surface of the concrete specimen as measurement area. This relies on the assumption that the concrete specimen behaves uniformly during plastic shrinkage in order to draw conclusions. This study developed a testing method for evaluating plastic shrinkage, plastic surface settlement and plastic shrinkage cracking throughout the depth of concrete specimens using digital image correlation. This was done to gain a better understanding of the behaviour of the concrete throughout its depth during shrinkage in the plastic state. This method was utilised to test the effect of an increase in climate severity on a standard concrete mix, the effect of an addition of a low volume of fibres to the standard concrete mix, as well as the effect of 100 % replacement of water with nanobubble water in the standard concrete mix. It is well known that fibres assist in minimising the propagation of plastic shrinkage cracks in concrete, however, the exact mechanism by which they assist is not understood. Therefore, an additional goal of this research was to study the effect that fibres have on mitigating plastic shrinkage cracking, as well as to explore the effect that nanobubbles could have on mitigating plastic shrinkage cracking. The results indicate that concrete follows a distinct pattern during plastic shrinkage when exposed to climates of increasing severity and that the top and bottom segments of a concrete specimen shrink at different rates. It is shown that the difference in shrinkage with depth can be used to quantify the effect that plastic shrinkage cracking mitigation measures such as fibres have. An equation to quantify plastic shrinkage cracking potential was developed and used to create a model to predict plastic shrinkage crack widths based on free shrinkage data. Based on the results of this study it is argued that fibres mitigate plastic shrinkage by the homogenisation of the entire concrete matrix throughout the depth prior to cracking, as well as reducing crack widening by the mechanism of crack bridging once cracking has occurred. This reduces the differential shrinkage rates of the top and bottom of the specimen during an increase in climate severity. Using the developed method for monitoring plastic shrinkage crack widening, it is also evident that the cracking that occurs below the surface, not measurable with traditional methods, is greater than the cracking that is visible on the surface. The effect of nanobubbles on mitigating plastic shrinking cracking shows promise in the reduction of crack widening, however further investigation is needed to understand the mechanisms behind any assistance that the nanobubbles provide in the mitigation of plastic shrinkage cracking understand the mechanisms behind any assistance that the nanobubbles provide in the mitigation of plastic shrinkage cracking. AFRIKAANS OPSOMMING: Plastiese krimpkrake is 'n bekende probleem in betonelemente, aangesien dit aan baie duursaamheidskwessies gekoppel word. Ten spyte daarvan dat plastiese krimping 'n goed nagevorsde onderwerp is, het die metodes vir die meting daarvan steeds beperkings. Tradisionele toetsmetodes vir plastiese krimp en plastiese krimp krake beskou slegs óf 'n enkele punt op of in 'n betonmonster of die sigbare oppervlak van die betonmonster as meetarea. Dit maak staat op die aanname dat die betonmonster eenvormig optree tydens plastiese krimping om gevolgtrekkings te maak. Hierdie studie het 'n toetsmetode ontwikkel vir die evaluering van plastiese krimping, plastiese oppervlakafsetting en plastiese krimpkrake dwarsdeur die diepte van betonmonsters deur gebruik te maak van digitale beeldkorrelasie. Dit is gedoen om 'n beter begrip te verkry van die gedrag van die beton regdeur sy diepte tydens krimping in die plastiese toestand. Hierdie metode is gebruik om die effek van 'n toename in klimaatserns op 'n standaardbetonmengsel te toets, die effek van 'n byvoeging van 'n lae volume vesel tot die standaardbetonmengsel, asook die effek van 100 % vervanging van water met nanoborrel water in die standaard betonmengsel. Dit is welbekend dat vesels help om die voortplanting van plastiese krimpkrake in beton te verminder, maar die presiese meganisme waardeur dit help word nie verstaan nie. Daarom was 'n addisionele doel van hierdie navorsing om die effek wat vesels het op die versagtende plastiese krimp krake te bestudeer, asook om die effek wat nanoborrels kan hê op versagtende plastiese krimp krake te ondersoek. Die resultate dui aan dat beton 'n duidelike patroon volg tydens plastiese krimping wanneer dit blootgestel word aan klimate van toenemende erns en dat die boonste en onderste segmente van 'n betonmonster teen verskillende tempo's krimp. Daar word aangetoon dat die verskil in krimping met diepte gebruik kan word om die effek wat plastiese krimpkrake versagtende maatreëls soos vesels het, te kwantifiseer. 'n Vergelyking om plastiese krimp krake potensiaal te kwantifiseer is ontwikkel en gebruik om 'n model te skep om plastiese krimp krake wydtes te voorspel gebaseer op vrye krimp data. Gebaseer op die resultate van hierdie studie word geargumenteer dat vesels plastiese krimping versag deur die homogenisering van die hele betonmatriks regdeur die diepte voor krake, sowel as om kraakverbreding te verminder deur die meganisme van kraakoorbrugging sodra krake plaasgevind het. Dit verminder die differensiële krimptempo's van die bo- en onderkant van die monster tydens 'n toename in klimaatserns. Deur gebruik te maak van die ontwikkelde metode vir die monitering van plastiese krimpkraakverbreding, is dit ook duidelik dat die krake wat onder die oppervlak voorkom, wat nie met tradisionele metodes meetbaar is nie, groter is as die krake wat op die oppervlak sigbaar is. Masters 2023-03-01T12:13:46Z 2023-05-18T07:10:40Z 2023-03-01T12:13:46Z 2023-05-18T07:10:40Z 2023-03 Thesis http://hdl.handle.net/10019.1/127224 en_ZA en_ZA Stellenbosch University, xvi, 103 pages : illustrations. application/pdf Stellenbosch : Stellenbosch University, |
| spellingShingle | Digital image correlation; plastic shrinkage; plastic shrinkage cracking; plastic settlement; concrete shrinkage Digital image correlation; Concrete -- Expansion and contraction Plastics -- Additives Plastics at high pressures Resin concrete Fenton, Craig Taylor Testing plastic shrinkage and cracking in concrete with an improved digital image correlation method |
| title | Testing plastic shrinkage and cracking in concrete with an improved digital image correlation method |
| title_full | Testing plastic shrinkage and cracking in concrete with an improved digital image correlation method |
| title_fullStr | Testing plastic shrinkage and cracking in concrete with an improved digital image correlation method |
| title_full_unstemmed | Testing plastic shrinkage and cracking in concrete with an improved digital image correlation method |
| title_short | Testing plastic shrinkage and cracking in concrete with an improved digital image correlation method |
| title_sort | testing plastic shrinkage and cracking in concrete with an improved digital image correlation method |
| topic | Digital image correlation; plastic shrinkage; plastic shrinkage cracking; plastic settlement; concrete shrinkage Digital image correlation; Concrete -- Expansion and contraction Plastics -- Additives Plastics at high pressures Resin concrete |
| url | http://hdl.handle.net/10019.1/127224 |
| work_keys_str_mv | AT fentoncraigtaylor testingplasticshrinkageandcrackinginconcretewithanimproveddigitalimagecorrelationmethod |