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Quantifying the cracking behaviour of strain hardening cement-based composites
Thesis (MScEng)--Stellenbosch University, 2012.
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| Format: | Thesis |
| Language: | en_ZA |
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Stellenbosch : Stellenbosch University
2012
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| _version_ | 1867613773787824128 |
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| access_status_str | Open Access |
| author | Nieuwoudt, Pieter Daniel |
| author2 | Boshoff, William Peter |
| author_browse | Boshoff, William Peter Nieuwoudt, Pieter Daniel |
| author_facet | Boshoff, William Peter Nieuwoudt, Pieter Daniel |
| author_sort | Nieuwoudt, Pieter Daniel |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (MScEng)--Stellenbosch University, 2012. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/20076 |
| institution | Stellenbosch University (South Africa) |
| language | en_ZA |
| last_indexed | 2026-06-10T12:41:28.315Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2012 |
| publishDateRange | 2012 |
| publishDateSort | 2012 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/20076 Quantifying the cracking behaviour of strain hardening cement-based composites Nieuwoudt, Pieter Daniel Boshoff, William Peter Stellenbosch University. Faculty of Engineering. Dept. of Civil Engineering. Strain hardening cement based composite (SHCC) High performance fibre reinforced cement-based composite (HPFRCC) Dissertations -- Civil engineering Theses -- Civil engineering Reinforced concrete -- Strains and stresses Reinforced concrete -- Cracking Thesis (MScEng)--Stellenbosch University, 2012. ENGLISH ABSTRACT: Strain Hardening Cement Based Composite (SHCC) is a type of High Performance Fibre Reinforced Cement-based Composite (HPFRCC). SHCC contains randomly distributed short fibres which improve the ductility of the material and can resist the full tensile load at strains up to 5 %. When SHCC is subjected to tensile loading, fine multiple cracking occurs that portrays a pseudo strain hardening effect as a result. The multiple cracking is what sets SHCC aside from conventional Reinforced Concrete (RC). Conventional RC forms one large crack that results in durability problems. The multiple cracks of SHCC typically have an average crack width of less than 80 μm (Adendorff, 2009), resulting in an improved durability compared to conventional RC. The aim of this research project is to quantify the cracking behaviour of SHCC which can be used to quantify the durability of SHCC. The cracking behaviour is described using a statistical distribution model, which represents the crack widths distribution and a mathematical expression that describes the crack pattern. The cracking behaviour was determined by measuring the cracks during quasi-static uni-axial tensile tests. The cracking data was collected with the aid of a non-contact surface strain measuring system, namely the ARAMIS system. An investigation was performed on the crack measuring setup (ARAMIS) to define a crack definition that was used during the determination of the cracking behaviour of SHCC. Several different statistical distributions were considered to describe the distribution of the crack widths of SHCC. A mathematical expression named the Crack Proximity Index (CPI) which represents the distances of the cracks to each other was used to describe the crack pattern of SHCC. The Gamma distribution was found to best represent the crack widths of SHCC. It was observed that different crack patterns can be found at the same tensile strain and that the CPI would differ even though the same crack width distribution was found. A statistical distribution model was therefore found to describe the CPI distribution of SHCC at different tensile strains and it was established that the Log-normal distribution best describes the CPI distribution of SHCC. After the cracking behaviour of SHCC was determined for quasi-static tensile loading, an investigation was performed to compare it to the cracking behaviour under flexural loading. A difference in the crack widths, number of cracks and crack pattern was found between bending and tension. Therefore it was concluded that the cracking behaviour for SHCC is different under flexural loading than in tension. AFRIKAANSE OPSOMMING: “Strain Hardening Cement-based Composite” (SHCC) is ‘n tipe “High Performance Fibre Reinforced Cement-based Composite” (HPFRCC). SHCC bevat kort vesels wat ewekansig verspreid is, wat die duktiliteit van die material verbeter en dit kan die maksimum trekkrag weerstaan tot en met ‘n vervorming van 5 %. Wanneer SHCC belas word met ‘n trekkrag, vorm verskeie fyn krake wat ‘n sogenaamde vervormingsverharding voorstel. Die verskeie krake onderskei SHCC van normale bewapende beton. Normale bewapende beton vorm een groot kraak met die gevolg dat duursaamheidsprobleme ontstaan. Die gemiddelde kraakwydte van SHCC is minder as 80 μm (Adendorff, 2009) en het dus ‘n beter duursaamheid as normale bewapende beton. Die doel van die navorsingsprojek is om die kraak gedrag van SHCC te kwantifiseer en wat dan gebruik kan word om die duursaamheid van SHCC te kwantifiseer. Die kraak gedrag is beskryf deur ‘n statistiese verspreiding model wat die kraak wydtes se verspreiding voorstel en ‘n wiskundige uitdrukking wat die kraak patroon beskryf. Die kraak gedrag was bepaal deur die krake te meet tydens die semi-statiese een-asige trek toetse. Die kraak data was met behulp van ‘n optiese vervormings toestel, naamlik die ARAMIS, versamel. ‘n Ondersoek is gedoen op die kraak meetings opstelling (ARAMIS), om ‘n kraak definisie te definieer wat gebruik is om die kraak gedrag te bepaal. Daar is gekyk na verskeie statistiese verdelings om die kraak wydtes van SHCC te beskryf. Die kraak patroon van SHCC is beskryf met ‘n wiskundige uitdrukking genoem die “Crack Proximity Index” (CPI) wat die krake se afstande van mekaar voorstel. Dit is bevind dat die Gamma verdeling die kraak wydtes van SHCC die beste beskryf. Daar is waargeneem dat verskillende kraak patrone by dieselfde vervorming verkry kan word en dat die CPI kan verskil al is die kraak wydte verdeling dieselfde. ‘n Statistiese verdelingsmodel is dus gevind om die CPI verdeling van SHCC te beskryf by verskillende vervormings, en daar is vasgestel dat die Log-normaal verdeling die CPI verdeling van SHCC die beste beskryf. Nadat die kraak gedrag van SHCC bepaal is vir semi-statiese trek-belasting, is ‘n ondersoek gedoen waar die trek-kraak gedrag vergelyk is met buig-kraak gedrag. ‘n Verskil in die kraak wydtes, aantal krake en kraak patroon is gevind tussen buiging en trek. Dus is die gevolgtrekking gemaak dat die kraak gedrag van SHCC verskillend is in buiging as in trek. 2012-03-09T12:38:39Z 2012-03-30T10:40:14Z 2012-03-09T12:38:39Z 2012-03-30T10:40:14Z 2012-03 Thesis http://hdl.handle.net/10019.1/20076 en_ZA Stellenbosch University 102 p. : ill. application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Strain hardening cement based composite (SHCC) High performance fibre reinforced cement-based composite (HPFRCC) Dissertations -- Civil engineering Theses -- Civil engineering Reinforced concrete -- Strains and stresses Reinforced concrete -- Cracking Nieuwoudt, Pieter Daniel Quantifying the cracking behaviour of strain hardening cement-based composites |
| title | Quantifying the cracking behaviour of strain hardening cement-based composites |
| title_full | Quantifying the cracking behaviour of strain hardening cement-based composites |
| title_fullStr | Quantifying the cracking behaviour of strain hardening cement-based composites |
| title_full_unstemmed | Quantifying the cracking behaviour of strain hardening cement-based composites |
| title_short | Quantifying the cracking behaviour of strain hardening cement-based composites |
| title_sort | quantifying the cracking behaviour of strain hardening cement based composites |
| topic | Strain hardening cement based composite (SHCC) High performance fibre reinforced cement-based composite (HPFRCC) Dissertations -- Civil engineering Theses -- Civil engineering Reinforced concrete -- Strains and stresses Reinforced concrete -- Cracking |
| url | http://hdl.handle.net/10019.1/20076 |
| work_keys_str_mv | AT nieuwoudtpieterdaniel quantifyingthecrackingbehaviourofstrainhardeningcementbasedcomposites |