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Using superabsorbent polymers in high performance concrete to mitigate autogenous and plastic shrinkage while observing the compressive strength
Thesis (MscEng)--Stellenbosch University, 2017.
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| Format: | Thesis |
| Language: | en_ZA |
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Stellenbosch : Stellenbosch University
2017
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| _version_ | 1867613850279346176 |
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| access_status_str | Open Access |
| author | Ebrahim, Nuraan |
| author2 | Boshoff, William Peter |
| author_browse | Boshoff, William Peter Ebrahim, Nuraan |
| author_facet | Boshoff, William Peter Ebrahim, Nuraan |
| author_sort | Ebrahim, Nuraan |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (MscEng)--Stellenbosch University, 2017. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/100934 |
| institution | Stellenbosch University (South Africa) |
| language | en_ZA |
| last_indexed | 2026-06-10T12:42:41.823Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2017 |
| publishDateRange | 2017 |
| publishDateSort | 2017 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/100934 Using superabsorbent polymers in high performance concrete to mitigate autogenous and plastic shrinkage while observing the compressive strength Ebrahim, Nuraan Boshoff, William Peter Combrinck, Riaan Stellenbosch University. Faculty of Engineering. Dept. of Civil Engineering. Polymers -- Absorption and adsorption Concrete -- Expansion and contraction High strength concrete Concrete -- Curing UCTD Thesis (MscEng)--Stellenbosch University, 2017. ENGLISH ABSTRACT: The use of high performance concrete (HPC) is relatively new in South Africa and guidelines on its production and use is lacking in the local construction industry. Conventional mix design methods are not suitable for HPC with low water to cement (w/c) ratios. A more sophisticated mix design approach is required. HPC with low w/c ratios tend to be sticky and have low workability. The high cement content also subjects the mix to early-age shrinkage and cracking. Conventional curing methods cannot be applied to low w/c ratio concretes to control shrinkage, due to its dense microstructure that inhibits the ingress of an external supply of curing water. This study involved a material selection process to develop a mix that has high strength as well as high flowability of both pastes and concrete. Autogenous shrinkage was tested on pastes and plastic shrinkage was tested on concretes. Plastic shrinkage cracking was also measured. However, it was found that the test method used for plastic shrinkage cracking is not suitable for HPC with low w/c ratios. Superabsorbent polymers (SAP), accompanied with additional water, was introduced as an internal curing agent. SAP was successful in reducing both autogenous and plastic shrinkage in all pastes and concretes, respectively. However, the presence of SAP and the extra water reduced the compressive strength in all pastes and concretes with the exception of one concrete mix variation. The variations in the mixes was the amount of internal curing water that was added to a given dosage of SAP. Previous literature reveals that the amount of internal curing water needed to saturate a SAP particle is often over estimated and leads to an effective increase in w/c ratio resulting in loss of strength. For this reason, the amount of internal curing water added was 50 and 75 % of the theoretical amount of water needed to saturate the SAP. Additionally, two different stone sizes, 6 and 9 mm, were also tested to observe the effect of larger aggregates on the desorption of SAP during mixing and setting. The results of the tests showed that w/c ratio, stone size, SAP dosage and amount of internal curing water have a combined effect on the early-age shrinkage and compressive strength development of both pastes and concretes. The optimum amount of water needed to reduce early-age shrinkage while maintaining a reasonable strength is not unique to a given w/c, stone size or SAP dosage only, but is unique to each combination and requires an excessive amount of testing to provide a guideline to the use of SAP in HPC. AFRIKAANSE OPSOMMING: Die gebruik van hoë werkverrigting beton (HWB) is relatief nuut in Suid-Afrika en daar is nie genoegsame riglyne beskikbaar oor die produksie en die gebruik daarvan in die plaaslike konstruksiebedryf nie. ‘n Konvensionele mengselontwerp metode van lae water-en-sement (w/s) verhouding is nie geskik vir HWB. ‘n Meer gesofistikeerde mengselontwerp word vereis. HWB met 'n lae w/s verhouding is geneig om taai te wees en het 'n lae werkbaarheid. Die hoë sement inhoud veroorsaak dat die mengsel meer geneig is na vroeë ouderdom krimp en kraak. Konvensionele rehabliteringsmetodes kan nie toegepas word op 'n lae w/s verhouding met die doel om die krimping van die beton te beheer nie. Die rede hiervoor is dat die beton se digte mikrostruktuur die invloei van eksterne water verhoed. Hierdie studie behels 'n keuringsproses om 'n mengsel wat 'n hoë sterkte asook 'n hoë vloeibaarheid van beide pastes en beton te ontwikkel. Outogene krimping is getoets op pastes en plastiese krimping is getoets op beton. Plastiese krimp krake is ook waargeneem. Daar is egter bevind dat die toetsmetode wat gebruik word vir plastiese krimp krake nie geskik is vir HWB met 'n lae w/s verhouding nie. Super absorberend polymeer (SAP), vergesel met bykomende water, is ingestel as 'n interne genesingsagent. SAP was suksesvol in die vermindering van beide outogene en plastiese krimping in alle pastes en beton. Maar die teenwoordigheid van SAP en die ekstra water verminderd die druksterkte in alle pastes en beton met die uitsondering van een betonmengsel variasie. Die verskille in die mengsels was die hoeveelheid van interne genesing water wat op 'n gegewe dosis van SAP bygevoeg is. Vorige literatuur toon dat die hoeveelheid interne genesing water wat benodig is om 'n SAP deeltjie te absorbeer, dikwels oorgeskat word en lei tot 'n effektiewe verhoging in w/s verhouding wat weer lei tot die verlies van sy sterkte. Om hierdie rede is die hoeveelheid internegenesing water wat bygevoeg is, 50 en 75 % van die hoeveelheid water wat teoreties benodig is om die SAP te versadig. Daarbenewens was twee verskillende klip groottes, 6 en 9 mm, ook getoets om die uitwerking van ‘n groter aggregaat op die desorpsie van SAP waar te neem tydens die vermenging en instelling van die beton. Die uitslae van die toetse het getoon dat ‘n w/s verhouding, klip grootte, SAP dosis en hoeveelheid interne genesing water 'n gekombineerde effek op die vroeë ouderdom krimping en druksterkte ontwikkeling van beide pastes en beton tot gevolg het. 2017-02-13T12:12:02Z 2017-03-29T11:48:12Z 2017-02-13T12:12:02Z 2017-03-29T11:48:12Z 2017-03 Thesis http://hdl.handle.net/10019.1/100934 en_ZA Stellenbosch University 205 pages : illustrations application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Polymers -- Absorption and adsorption Concrete -- Expansion and contraction High strength concrete Concrete -- Curing UCTD Ebrahim, Nuraan Using superabsorbent polymers in high performance concrete to mitigate autogenous and plastic shrinkage while observing the compressive strength |
| title | Using superabsorbent polymers in high performance concrete to mitigate autogenous and plastic shrinkage while observing the compressive strength |
| title_full | Using superabsorbent polymers in high performance concrete to mitigate autogenous and plastic shrinkage while observing the compressive strength |
| title_fullStr | Using superabsorbent polymers in high performance concrete to mitigate autogenous and plastic shrinkage while observing the compressive strength |
| title_full_unstemmed | Using superabsorbent polymers in high performance concrete to mitigate autogenous and plastic shrinkage while observing the compressive strength |
| title_short | Using superabsorbent polymers in high performance concrete to mitigate autogenous and plastic shrinkage while observing the compressive strength |
| title_sort | using superabsorbent polymers in high performance concrete to mitigate autogenous and plastic shrinkage while observing the compressive strength |
| topic | Polymers -- Absorption and adsorption Concrete -- Expansion and contraction High strength concrete Concrete -- Curing UCTD |
| url | http://hdl.handle.net/10019.1/100934 |
| work_keys_str_mv | AT ebrahimnuraan usingsuperabsorbentpolymersinhighperformanceconcretetomitigateautogenousandplasticshrinkagewhileobservingthecompressivestrength |