Manufacturing processes for engineered cement-based composite material products

De Koker, Don ; Van Zijl, G. P. A. G. (2004-12)

Thesis (MScEng)--University of Stellenbosch, 2004.

Thesis

ENGLISH ABSTRACT: The effort to modify the brittle behaviour of plain cement materials such as cement pastes, mortars and concretes has resulted in the modern concepts of fibre reinforcement and matrixfibre interface engineering. The behaviour of such modern cement-based materials is characterized by a more ductile post-peak softening in uni-axial tension compared with the plain, unreinforced matrix. This is as a result of balancing the matrix strength and toughness with fibre bond and strength. The mechanical response shows a sustained or even higher tensile load carrying capacity after first cracking of the matrix. This class of fibre reinforced composites, designed to exhibit such pseudo-strain hardening properties based on micromechanical principles, are referred to as engineered cement-based composites (ECC). ECC are manufactured by either cast moulding, extrusion or spinning (in the case of pipes). Different manufacturing techniques lead to different performance of composites. Researching the micro-mechanical aspects of ECC, particularly fibre orientation and fibrematrix interfacial bond strength, leads to a better understanding of the strength characteristics and mechanical behaviour. Moreover, the manufacturing process significantly influences these characteristics. Here lies the focus of this research. The research consisted of an in-depth research, literature study and understanding of ECC technology, developing extrusion and cast equipment, developing laboratory testing equipment for pipe testing, tailoring the ECC mix for the specific purpose of manufacture, manufacturing of ECC plate and pipe samples, testing of ECC for various manufacturing techniques and scrutinising/ analysing the results for recommendations with respect to further research and commercialisation of ECC material products.

AFRIKAANSE OPSOMMING: Beton, mortel en sement produkte se bros gedrag onder belasting het nuwe konsepte in veselversterkte bewapening tot gevolg gehad. Veselversterkte beton se gedrag word gekarakteriseer deur die verhoogde weerstand in trek na aanvanklike faling. Deur die matrikssterkte en die veselkarakteristieke te balanseer, kan veelvuldige krake veroorsaak word, met gepaardgaande geleidelike weerstandsverhoging. Hierdie klas van veselversterkte sement produkte word na verwys as ‘Engineered Cement-based Composites’ (ECC). ECC produkte kan vervaardig word deur die produk te giet, te ekstrueer of in die geval van pype, te spin. Die vervaardigingsproses het ‘n noemenswaardige invloed op die sterktegedrag van die ECC. Ondersoek na die mikro-meganiese gedrag van ECC, hoofsaaklik veseloriëntasie en die vesel-matriks interaksie, is nodig om die sterkte-gedrag van ECC te verstaan en verder te ontwikkel binne die raamwerk van die spesifieke vervaadigingsmetodes. Hier lê die fokus van hierdie studie. Die navorsing het die volgende behels: deeglike literatuurstudie, die ontwikkeling van apparatuur vir ekstrusie en giet, die ontwikkeling van laboratorium toetsapparatuur (vir pype), ECC mengontwerp vir die spesifieke vervaardigingstegnieke, vervaadiging van ECC plaat-monsters en pyp-monsters, die toets daarvan en interpretasie van resultate met betrekking tot die maak van aanbevelings ten opsigte van verdere navorsing en kommersialisering van ontwikkelde tegnologie.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/16300
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