Thesis (MScEng)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Surface seals are widely used in South Africa. There are a number of reasons which include
affordability, versatility and durability. There are, however, in some cases problems with stone
loss that can lead to a shortened lifespan of the pavement. The loss of aggregate chippings in
surface seals poses a major problem in the seal pavement industry. This study aims to identify
the influencing factors that lead to these adhesive failures as well as to find optimum
combinations of binders and aggregates at various conditions.
Various binders commonly used in South African surface seal construction will be tested using
the Bitumen Bond Strength (BBS) test method. The binders used in the study include 80/100
penetration grade bitumen, elastomer modified bitumen, bitumen rubber, elastomer modified
emulsion and cationic rapid setting emulsion. Aggregates used in the study include dolerite,
granite and quartzite. The test samples were cured and tested at two temperatures, 15 °C and
35 °C. The samples were also cured for 2, 6 and 24 hours respectively.
The study tackles a wide range of variables in order to obtain a good understanding of adhesion
properties of surface seals used in South Africa. Tests were repeated at least once to ensure
repeatability and in some cases up to four repeats were performed. The loading rate at which
the tests were performed had a significant influence on the BBS results. This rate varied which
complicated the process of comparing the results. It was therefore decided to unify the loading
rates.
The BBS results exposed the difference between hot applied binders and emulsions. The
former having significant stronger adhesion properties. It was also confirmed by the results that
temperature plays a key role in the BBS results due to the visco-elastic properties of bitumen.
These influences will be discussed along with others such as aggregate types and curing times.
The type of failure is also discussed. Failure can either be adhesive or cohesive, the former
being a failure between the aggregate and the binder while the later refers to a failure in the
binder itself. The results of other students will also be discussed and compared to the results of this study.
These include results of predecessors that tested emulsions as well as results from tests done
on fractured aggregate surfaces and precoated aggregates. This study showed very similar
results as these from other students, except for tests done with emulsions. It was discovered that the method of curing of the emulsions must be adapted to ensure proper curing of the
emulsions.
It was found that aggregates did not influence the BBS properties to the same extent as
temperature and binder application type. The BBS results of hot applied binders also did not
significantly increase as the curing time increased, but the results of emulsions showed some
increase. However, the emulsions needed more time to cure properly. / AFRIKAANSE OPSOMMING: Oppervlak seëls word algemeen gebruik in Suid-Afrika. Daar is verskeie redes hiervoor
waaronder bekostigbaarheid,veelsydigheid en duursaamheid. Daar is egter in sommige gevalle
probleme met klipverlies wat kan lei tot n verkorte leeftyd. Hierdie klipverlies ontstaan as gevolg
van verskeie redes of kombinasies daarvan. Die studie beoog om hierdie faktore wat die
adhesie eienskappe beïnvloed te identifiseer sowel as om optimum kobinasies van bindmiddels
en klipsoorte te bewerkstellig by verkeie kondisies.
‘n Verskeidenheid van bindmiddels wat algemeen in Suid-Afrika gebruik word, word in die studie
getoets met die Bitumen Bond Sterkte (BBS) toets metode. Die bindmiddels wat in die studie
gebruik word sluit 80/100 penetrasie graad bitumen, elastomeer gemodifiseerde bitumen,
bitumen rubber, elastomeer gemodifiseerde emulsie en kationiese snel settende emulsie. Die
klipsoorte wat vir die studie gebruikword is doleriet, graniet en kwartsiet. Hierdie gesteentes
word algemeen in die praktyk gebruik. Die toets monsters word ook by twee temperature gekuur
en getoets. Hierdie temperature is 15 °C en 35 °C. Die toets monsters word ook onderskeidelik
vir 2, 6 en 24 uur gekuur.
Die studie ondersoek 'n wye verskeidenheid van veranderlikes om sodoende 'n goeie begrip
van adhesie eienskappe van die oppervlak seëls wat in Suid-Afrika gebruik word te verkry. Elke
toets was ten minste een maal herhaal om herhaalbaarheid te verseker. Sommige toetse was
tot 4 keer herhaal. Die belasting tempo van die toetse het ‘n beduidende uitwerking op die BBS
resultate as gevolg van die visko-elastiese eienskappe van bitumen. Hierdie tempo het gewissel
en dit moeilik gemaak om die resultate te vergelyk. Daarom was daar besluit om die tempo van
die toetse te verander na ‘n gelykvormige tempo.
Daar was ‘n duidelike verskil in BBS resultate van die warm toegepaste bindmiddels en die
emulsies. Die warm bindmiddels het baie hoër BBS resultate gelwer. Dit was ook bevestig in die
resultate dat temperatuur ‘n beduidende rol speel in die BBS. Hierdie invloede sal bespreek
word tesame met ander, soos klipsoorte en kuring tye. Die tipe versaking word ook bespreek.
Versaking kan plaasvind as gevolg van adhesie of cohesie, waar adhesie versaking 'n
versaking is tussen die klip en die bindmiddel terwyl cohesie versaking verwys na 'n versaking
in die bindmiddel self. Die uitslae van die ander studente sal ook bespreek word en vergelyking word met die resultate
van hierdie studie. Dit sluit die resultate van voorgangers in wat emulsies getoets het sowel as
die resultate van toetse wat gedoen is op gebreekte klipoppervlaktes en bitumen behandelde klippe. Hierdie studie het baie soortgelyke resultate getoon as dié van ander studente, behalwe
vir die toetse wat gedoen was met emulsies. Daar is vasgestel dat die metode van kuring van
die emulsies moet aangepas word om behoorlike kuring van die emulsies te verseker.
Daar is ook gevind dat klipsoorte nie die BBS eienskappe in dieselfde mate as temperatuur en
bindmiddel toepassingstipe beïnvloed het nie. Die BBS resultate van warm aangewende
bindmiddels het ook nie aansienlik verhoog soos die kuringstyd toegeneem het nie, maar die
resultate van emulsies het wel 'n toename getoon. Die emulsies het wel meer tyd nodig gehad
om behoorlik te kuur.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/95882 |
| Date | 12 1900 |
| Creators | Lombard, Le Riche |
| Contributors | Jenkins, Kim Jonathan, Stellenbosch University. Faculty of Engineering. Department of Civil Engineering. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | Unknown |
| Type | Thesis |
| Format | xv, 119, lxxxvi p. : ill. |
| Rights | Stellenbosch University |
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