Formwork pressures by self-compacting concrete: a practical perspective
| dc.contributor.advisor | Wium, Jan | en_ZA |
| dc.contributor.advisor | Jurgens, Chris | en_ZA |
| dc.contributor.author | Labuschagne, Jean-Claude | en_ZA |
| dc.contributor.other | Stellenbosch University. Faculty of Engineering. Dept. Civil Engineering. | en_ZA |
| dc.date.accessioned | 2018-02-14T11:44:15Z | |
| dc.date.accessioned | 2018-04-09T06:55:05Z | |
| dc.date.available | 2018-02-14T11:44:15Z | |
| dc.date.available | 2018-04-09T06:55:05Z | |
| dc.date.issued | 2018-03 | |
| dc.description | Thesis (MEng)--Stellenbosch University, 2018. | en_ZA |
| dc.description.abstract | ENGLISH ABSTRACT: One of the challenges facing the South African construction industry is the prediction of lateral formwork pressure exerted by Self-Compacting Concrete. A major hindrance to the increased use of Self-Compacting Concrete (SCC) in cast-in-place applications in the South African construction industry is the lack of information about and understanding of, lateral formwork pressure exerted by SCC. There are no accepted standardised codes or guidelines for the local construction industry that can be used to facilitate the design of formwork for predicting formwork pressure exerted by SCC. Formwork systems designers have been encouraged to design formwork to withstand full hydrostatic pressures, unless a method based on appropriate and reliable experimental data is available. This generally limits contractors to low wall or extremely strong formwork, which can lead to extra formwork costs. Numerous parameters, including placement conditions, material properties and formwork characteristics can influence lateral formwork pressure. This study presents the results of an experimental investigation undertaken using on-site conditions, aimed at studying the influence of placement methods (top-down and bottom-up pumping), of various casting rates, as well as implementing predetermined waiting periods of 10 and 15 minutes between castings. The influence of each of these parameters was evaluated by using six vertical instrumented wall elements. All six walls were fitted with eight flush diaphragms transducers and were identical in dimensions (5.4 m x 2.0 m x 0.25 m). The test results show that with high casting rates from the top of the formwork system, hydrostatic pressure can be expected. It was shown that by interrupting the casting procedure and implementing waiting periods to allow the fresh SCC to set, decreased the lateral pressure exerted. It was found that, when pumping from the base of the formwork system at high casting rates, hydrostatic pressure could be expected during the casting process and that lateral pressures above the hydrostatic pressure could be expected during the casting of the SCC. The knowledge gained in this study can therefore be used to lay the foundation for future studies for the prediction of lateral pressure exerted on formwork by SCC under South African conditions. | en_ZA |
| dc.description.abstract | AFRIKAANSE OPSOMMING: Een van die uitdagings vir die Suid Afrikaanse konstruksie industrie is tans in die gebied van die laterale druk wat op bekisting uitgeoefen word deur selfkompaktende beton (SCC), en spesifiek die akkurate voorspelling van hierdie druk. ‘n Groot hindernis tot die meer algemene gebruik van SCC in die giet van beton in die Suid Afrikaanse konstruksie industrie is die gebrek aan inligting oor, en die begrip van, die laterale druk wat op bekisting uitgeoefen word deur SCC. Daar bestaan geen aanvaarde standaard kodes of riglyne vir die plaaslike konstruksie industrie om die ontwerp van bekisting te vergemaklik deur die laterale druk van SCC op bekisting te voorspel nie. Bekisting stelselontwerpers word aangemoedig om bekisting te ontwerp om die volle hidrostatiese druk te kan weerstaan, tensy ‘n ander metode beskikbaar is wat op toepaslik en betroubare data gebasseer is. Dit beperk kontrakteurs gewoonlik tot of lae muur of uiters sterk bekisting, wat tot hoë bekistingskoste kan lei. Verskeie parameters, insluitend plasingstoestande, material eienskappe en bekistingseienskappe, kan die laterale druk van SCC op bekisting beïnvloed. Hierdie studie verskaf resultate van ‘n eksperimentele ondersoek wat onder terrein toestande onderneem is, met die doel om die invloed van plasingsmethodes te bepaal (van bo na onder gepomp, sowel as van onder na bo), van verskillende giet-tempos, sowel as voorafbepaalde wagperiodes met duurtes van 10 en 15 minute tussen gietperiodes. Die invloed van elk van die parameters is evalueer deur die gebruik van ses vertikale muurelemente met gemonteerde drukmeters. Op elke muurelement is agt diafragma sensors gemonteer. Die afmetings van al die mure was dieselfde (5.4 m x 2.0 m x 0.25 m). Die toetsresultate toon dat ‘n hoë giet-tempo vanaf die bokant van die bekistingstelsel, ‘n hidrostatiese druk tot gevolg het. Dit is bewys dat onderbreking van hierdie gietproses met wagperiodes, wat toelaat dat die vars SCC kan set, die laterale druk op die bekisting verminder. Dit is gevind dat, wanneer SCC vanaf die onderkant van die bekisting gepomp word teen ‘n hoë tempo, hidrostatiese druk verwag kan word teen die einde van die gietproses en dat laterale druk op die bekisting bo hidrostatiese druk sal styg tydens die gietproses. Die kennis verwerf tydens hierdie studie kan dus van nut wees as die basis vir toekomstige studies wat kan lei tot die akkurate voorspelling van die laterale druk van SCC op die bekisting onder verskillende omstandighede in Suid Afrika. | af_ZA |
| dc.format.extent | 183 pages : illustrations | en_ZA |
| dc.identifier.uri | http://hdl.handle.net/10019.1/103400 | |
| dc.language.iso | en_ZA | en_ZA |
| dc.publisher | Stellenbosch : Stellenbosch University | en_ZA |
| dc.rights.holder | Stellenbosch University | en_ZA |
| dc.subject | Formwork | en_ZA |
| dc.subject | Self-compacting concrete | en_ZA |
| dc.subject | Construction industry | en_ZA |
| dc.subject | Self-consolidating concrete | en_ZA |
| dc.subject | UCTD | en_ZA |
| dc.title | Formwork pressures by self-compacting concrete: a practical perspective | en_ZA |
| dc.type | Thesis | en_ZA |