3D Printing of rapid setting ordinary concrete mixtures
| dc.contributor.advisor | Combrinck, Riaan | en_ZA |
| dc.contributor.advisor | Kruger, Pienaar Jacques | en_ZA |
| dc.contributor.author | Gunzel, Friedhelm Stefan | en_ZA |
| dc.contributor.other | Stellenbosch University. Faculty of Engineering. Dept. of Civil Engineering. | en_ZA |
| dc.date.accessioned | 2021-11-18T07:15:14Z | |
| dc.date.accessioned | 2021-12-22T14:21:31Z | |
| dc.date.available | 2021-11-18T07:15:14Z | |
| dc.date.available | 2021-12-22T14:21:31Z | |
| dc.date.issued | 2021-12 | |
| dc.description | Thesis (MEng)--Stellenbosch University, 2021. | en_ZA |
| dc.description.abstract | ENGLISH ABSTRACT: In recent years, significant research and development has gone into 3D printed concrete. This construction technique requires no formwork as in ordinary construction projects. The addition of admixtures increases the complexity of 3D printable mixtures in comparison to ordinary concrete mixtures in which cement, water and aggregate are the main constituents. In this study, more ordinary concrete mixtures are used for 3D printing in order to minimise the complexity of 3D printable mixtures. The combination of a more ordinary concrete mixture with the efficiency of 3D printing as a construction technique, combines the benefits of both construction techniques. The aim was to 3D print ordinary concrete mixtures that have improved buildability characteristics due to a rapid setting behaviour. Three types of rapid setting behaviours were tested in this study: false setting, ordinary Portland cement (OPC) cement replacement with belitic calcium sulfoaluminate (BCSA) cement and flash setting. The study was conducted in two phases. The first phase was used to characterise the three rapid setting mixtures. Compressive strength, hydration temperature development, setting time and early age compressive strength were tested for the characterisation. In the second phase, the three rapid setting mechanisms were printed in a 3D printer to determine the buildability of the three rapid setting mechanisms. In addition to buildability, the economic feasibility of the rapid setting mixtures was analysed. It was found that false setting does not significantly influence the mechanical characteristics of concrete. The early age strength gain is not as rapid as for flash setting or with the addition of BCSA cement. Flash setting improves the early ages strength gain of concrete but reduces the long-term compressive strength development. Replacing OPC cement with BCSA cement improves the early age strength gain and does not impact the mechanical properties significantly. Higher cement replacement rates increased the intensity of the rapid setting mechanisms, shorter setting times and higher early age strength was improved. From the buildability study it was found that flash setting has the largest positive impact on the buildability characteristics of 3D printed concrete. The buildability could be increased by 321% with flash setting. OPC cement replacement with BCSA cement resulted in a buildability increase of 214%. False setting was found to be the least effective rapid setting mechanism with a 35% increase in buildability. Flash setting and BCSA replacement are cost effective methods to improve the buildability of 3D printed concrete. False setting is found too expensive to induce and the compressive strength gain at early ages is little compared to the other two rapid setting mechanisms. The aim of this study was achieved by 3D printing rapid setting ordinary concrete mixtures. Significant buildability improvements could be made, and the rapid setting ordinary concrete mixtures are beneficial for the rapid construction of 3D printed components or structures. | en_ZA |
| dc.description.abstract | AFRIKAANSE OPSOMMING: In die afgelope paar jare was daar beduidende navorsing en ontwikkeling in 3D gedrukte beton. Hierdie konstruksie tegniek vereis geen bekisting soos vir gewone bouprojekte nie. Die toevoeging van bymiddels verhoog die kompleksiteit van 3D drukbare mengsels in vergelyking met gewone betonmengsels waarin sement, water en aggregaat die belangrikste bestanddele is. In hierdie studie word gewone betonmengsels gebruik, om die kompleksiteit van 3D drukbare menge te verminder. Die doelwit is om gewone betonmengsels te druk, met beter boubaarheid. Drie tipes vinnige settingsgedrag is in hierdie studie getoets: valsset, vervanging van OPC-sement met BCSA-sement en flitsset. Die studie is in twee fases uitgevoer. Die eerste fase is gebruik om die drie vinnige settings- mengsels te kenmerk. Druksterkte, ontwikkeling van hidrasie temperatuur, stettings tyd en druksterkte op vroeë ouderdom is getoets vir die karakterisering. In die tweede fase is die drie vinnige settings mengsels in 3D gedruk om die boubaarheid van die drie mengsels te bepaal. Benewens die boubaarheid, word die ekonomiese lewensvatbaarheid van die mengsels met 'n vinnige setting ontleed. Daar is gevind, dat valsset nie die meganiese eienskappe van beton beduidend beïnvloed nie. Die toename in sterkte op vroeë ouderdom is nie so groot soos by flitsset of met die toevoeging van BCSA sement nie. Flitsset verbeter die vroeë ouderdom sterkte van beton, maar verminder die ontwikkeling van druksterkte in die langtermyn. Deur OPC-sement met BCSA-sement te vervang, word die vroeë ouderdom sterkte van die beton verbeter terwyl die meganiese eienskappe nie aansienlik beïnvloed word nie. Sement met hoër vervangingsyfers het die intensiteit van die flitsset meganismes verhoog, korter settye en hoër vroeë druk sterkte kon gemeet word. Uit die boubaarheidstudie is gevind dat flitsset ‘n positiewe impak op die boubaarheidseienskappe van 3D gedrukte beton het. Die boubaarheid het met flitsset met 321% verhoog. Die OPC sementvervanging met BCSA sement het 'n toename in boubaarheid van 214% tot gevolg gehad. Daar is bevind dat valsset die minste effektiewe vinnige set meganisme is, met 'n toename in boubaarheid van 35%. Flitsset en BCSA vervanging is koste effektiewe metodes om die boubaarheid van 3D gedrukte beton te verbeter. Valsset is te duur bevind, en die toename in druk sterkte op 'n vroeë ouderdom is min in vergelyking met die ander twee set meganismes. Die doel van hierdie studie is bereik, deur die 3D druk van gewone betonmengsels met vinnig set eienskappe. Aansienlike verbeterings in boubaarheid kan aangebring word, en die vinnige setting van gewone betonmengsels is voordelig vir die vinnige konstruksie van 3D gedrukte komponente of strukture. | af_ZA |
| dc.description.version | Masters | en_ZA |
| dc.format.extent | 125 pages | en_ZA |
| dc.identifier.uri | http://hdl.handle.net/10019.1/123789 | |
| dc.language.iso | en_ZA | en_ZA |
| dc.publisher | Stellenbosch : Stellenbosch University | en_ZA |
| dc.rights.holder | Stellenbosch University | en_ZA |
| dc.subject | 3D printing -- Concrete | en_ZA |
| dc.subject | Flash setting | en_ZA |
| dc.subject | Belitic calcium sulfoaluminate -- Cement | en_ZA |
| dc.subject | Rapid solidification processing | en_ZA |
| dc.subject | Concrete -- Drying | en_ZA |
| dc.subject | UCTD | en_ZA |
| dc.title | 3D Printing of rapid setting ordinary concrete mixtures | en_ZA |
| dc.type | Thesis | en_ZA |