Thesis (MScEng)--Stellenbosch University, 2011. / ENGLISH ABSTRACT: Strain hardening cement‐based composites (SHCC) are fibre‐reinforced composites designed to form
multiple fine cracks under tensile and flexural load. The cracks are controlled to small widths, whereby
significant toughness, or energy dissipation, is realised on the one hand, and high resistance to gas and
liquid ingress is maintained on the other hand. These two physical phenomena define application fields
of SHCC, i.e. for instance elements of buildings and infrastructure for enhanced earthquake resistance,
and protection of steel bars under service loads which lead to crack formation. Also exploiting the
potential protection offered by SHCC to existing structures, thin overlays have been applied to existing
dam faces, reinforced concrete retaining walls, water channels and RC road pavements. The layers vary
between 20 and 40 mm in thickness. Considering the fibre length, usually 8 or 12 mm, as well as the
application method, such thin layers may have dominantly two dimensional fibre orientation, with little
or no component in the layer thickness direction. While several research groups have performed
uniaxial tensile tests and flexural tests on SHCC specimens, little or no information is available on SHCC
response to biaxial loading, as is to be expected in road pavement repair layers, or other repair layers.
This paper reports the results of biaxial testing of 20 mm thick SHCC specimens produced in such a way
to have dominantly two‐dimensional fibre orientation, and another group of specimens produced by
cutting from larger specimens, whereby three‐dimensional fibre orientation was preserved in the
resulting 20 mm thick specimens. Biaxial tests were performed in three quadrants, i.e. compressioncompression,
compression‐tension, and tension‐tension. A clear fibre orientation‐related difference in
the failure patterns involves out‐of‐plane splitting under biaxial compression of specimens with twodimensional
fibre orientation, at significantly lower load, as opposed to in‐plane tensile splitting of
specimens containing three‐dimensional fibre orientation. / AFRIKAANSE OPSOMMING: Vervormingsverhardende sement‐gebaseerde saamgestelde materiale (SHCC) is veselversterke
saamgestelde materiale wat ontwerp is om verskeie fyn krakies te vorm onder trekspanning en buig
spanning. Die kraakbreedtes word beheer, waardeur betekenisvolle taaiheid verkry, of energie verlies
beheer word aan die een kant, en die hoë weerstand teen die gas en die vloeistof penetrasie aan die
ander kant gehandhaaf word. Hierdie twee fisiese verskynsels definieer die toepassingsvelde van SHCC,
d.w.s vir byvoorbeeld elemente van geboue en infrastruktuur vir verbeterde aardbewing weerstand, en
die beskerming van staal stawe onder die dienslaste wat lei vorming te kraak. By eksploitasie van die
potensiële beskerming aangebied deur SHCC aan bestaande strukture, is dun oorlae op bestaande dam
walle, versterkte beton keermure, water kanale en staal‐versterkte beton paaie gebruik. Die SHCC lae
wissel tussen 20 en 40 mm in dikte. Met inagneming van die vesel lengte, gewoonlik 8 of 12 mm, sowel
as die toepassingsmetode, kan so 'n dun lag ‘n oorheersend tweedimensionele vesel oriëntasie hê, met
min of geen komponent in die rigting van die laag dikte nie. Terwyl verskeie navorsingsgroepe eenassige
trektoetse en buigtoetse op SHCC monsters gedoen het; is daar min of geen inligting beskikbaar op SHCC
se reaksie op biaksiale belasting, soos verwag kan word in die pad herstel lae, of ander herstel lae.
Hierdie verslag rapporteer die resultate van die biaksiale toetsing van 20 mm dik SHCC monsters wat op
so 'n manier gemaak word om dominante twee‐dimensionele vesel oriëntasie te hê, en 'n ander groep
monsters wat deur die sny van groter monsters, waarvolgens die drie‐dimensionele vesel oriëntasie
verseker is. Biaksiale toetse is uitgevoer in drie kwadrante, d.w.s druk‐druk, druk‐trek en trek‐trek. 'n
Duidelike verskil in die falingspatrone, aan die hand van vesel oriëntasie, behels uit‐vlak splyting onder
biaksiale toetsing van monsters met twee‐dimensionele vesel oriëntasie, op 'n aansienlik laer lading, in
teenstelling met die in‐vlak trek splyting van monsters wat ‘n drie‐dimensionele vesel oriëntasie het.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/17806 |
| Date | 12 1900 |
| Creators | Swanepoel, Willie |
| Contributors | Van Zijl, G. P. A. G., Stellenbosch University. Faculty of Engineering. Dept. of Civil Engineering. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | Unknown |
| Type | Thesis |
| Format | 111 p. : ill. |
| Rights | Stellenbosch University |
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