Thesis (MScEng (Civil Engineering))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: The research conducted in this study forms part of the Phase II process of the Bitumen
Stabilized Materials (BSMs) Guideline improvement initiative. The initiative aims to address
areas of concern in the cold mix design procedures for BSMs.
Current road rehabilitation using the bitumen stabilization process requires testing of
representative specimens as means to evaluate pavement performance over time. In order to
adequately acquire specimens representative of field conditions, it is necessary to condition the
materials in a process called curing. Although curing procedures have been standard in many
countries on different continents, the protocols are varied and an acceptable procedure is
currently not available.
In order to develop an acceptable curing protocol for BSMs, both field and laboratory
environments were investigated. Considering that curing takes time in the field, production of
representative samples intended for laboratory testing must undergo accelerated curing in the
laboratory. Given the complexities involved in achieving close correlations between field and
laboratory environments, the research strived to reconcile field and laboratory material
behaviour. In particular, the main objective of the research was to unify the curing protocol for
BSMs, with the standardization of the curing protocol being top priority.
In this study, laboratory results have confirmed that the different natures of curing mechanisms
inherent in a BSM-foam and BSM-emulsion contribute to irreconcilable material behaviour(s).
Results have confirmed that curing of BSM-foam is largely a function of water repulsion, with the
addition of active filler dominating material performance almost immediately. Unlike BSM-foam,
curing of BSM-emulsion is both a function of the breaking of emulsion during the initial phase
and the gradual release of moisture with time. In this instance, BSM-emulsion material
performance resembled active filler influences past the breaking of the emulsion cycle.
Consequently, given the observed differences regarding material behaviour(s), the unification of
the curing protocol for BSMs has not been successful.
In terms of accommodation of active filler in the final curing protocol for BSMs, findings in this
research have revealed that active filler’s tendency to absorb moisture in the initial stages
requires longer curing time to help extract the absorbed moisture during the curing process.
Although the use of active filler has an impact on curing, its inclusion in a BSM does not justify
its extension in the curing time as cementation is not one of the desired properties of these
materials. BSMs are primarily desirable for their flexibility in pavement structures. For this
reason, active filler was omitted in the final curing protocol due to reasons of simplifying the mix
design process.
In conclusion, different curing protocols were tested and developed to help produce reconcilable
material behaviour in both the field and laboratory environments. Through the reconciliation of
key material properties such as the resilient modulus, long term equilibrium moisture conditions
and shear parameters, an acceptable standardized curing protocol for BSM-foam and BSMemulsion
intended for application in industrial laboratories across South Africa was successfully
developed. / AFRIKAANSE OPSOMMING: Die navorsing tydens hierdie studie gedoen, vorm deel van die Tweede fase van die Bitumen
Gestabiliseerde Materiale Riglyne verbeteringsinisiatief. Die inisiatief het ten doel om areas van
bekommernis in die kouemengsel-ontwerp-prosedures vir Bitumen Gestabiliseerde Materiale
aan te spreek.
Huidige padrehabilitasie wat gebruik maak van die Bitumen Gestabiliseerde Materiale proses,
vereis toetsing van verteenwoordigende monsters om sodoende plaveiselgedrag oor ‘n tydperk
te evalueer. Materiale moet deur die verouderingsproses gekondisioneer word, om sodoende
monsters te verkry wat akkuraat verteenwoordigend van veldtoestande is. Alhoewel
verouderingsprosesse in meeste lande - op verskillende kontinente - gestandariseerd is, is die
protokol verskillend en ‘n aanvaarbare prosedure is nie tans beskikbaar nie.
Beide veld- en laboratoriumomgewings is ondersoek, om sodoende ‘n aanvaarbare
verouderings-protokol vir Bitumen Gestabiliseerde Materiale te ontwikkel. Wanneer in ag
geneem word dat veroudering in die veld tydrowend is, moet vervaardiging van
verteenwoordigende monsters vir laboratoriumgebruik versnelde veroudering in die
laboratoruim ondergaan. Gegee die kompleksiteite betrokke om goeie korrelasie tussen velden
laboratoriumomgewings te verkry, het die navorsing daarna gestreef om die veld- en
laboratoriummateriaalgedrag te verenig. Die hoofdoel van die navorsing was om die
verouderingsprotokol vir Bitumen Gestabiliseerde Materiale te verenig met die stardaardisering
van die verouderingsprotokol as top prioriteit.
In hierdie studie het laboratorium resultate bevestig dat die verskillende aard van
voorbereidings- meganismes inherent in BSM-skuim en BSM-emulsie bydra tot onversoenbare
materiaalgedrag. Resultate het bevestig dat voorbereiding van BSM-skuim ’n funksie van
waterrepulsie het en met die byvoeging van aktiewe vullers dominieer dit die materiaalgedrag
byna onmiddelik. Anders as BSM-skuim is die voorbereiding van BSM-emulsie beide ’n funksie
vir die breek van emulsie tydens die begin fase en die geleidelike vrystelling van vog oor tyd. In
hierdie geval het BSM-emulsie se materiaalgedrag die invloed van aktiewe vuller getoon nadat
die emulsie gebreek het. Gevolglik, weens die waargenome verskille rakende materiaalgedrag
is die vereniging van die voorbereidings- protokols vir BSMs nie suksesvol nie.
In terme van inagneming van aktiewe vullers in die finale voorbereidingsprotokol vir BSM’s, is
deur navorsing bevind dat aktiewe vullers neig se neiging om vog te absorbeer in die
beginstadia dit benodig dus ‘n langer verouderingstyd vir die ontrekking van die geabsorbeerde
vog. Hoewel die gebruik van aktiewe vullers ’n impak het op die voorbereiding, reverdig dit nie
die verlenging van die verouderingstyd vir die insluiting daarvan in BSM nie, siende dat
sementering nie een van die gewenste eienskappe van hierdie materiaal is nie. BSMs word
hoofsaaklik verkies vir sy buigsaamheid in paveiselsturkture. Om die mengselontwerp prosesse
te vereenvoudig, was aktiewe vullers dus weggelaat in die finale voorbereidingsprotokol.
Ter afsluiting was verskeie voorbereidings protokolle getoets en ontwikkel om te help met die
vervaardiging van versoenbare materaalgedrag in beide veld-en-laboratoriumomgewings. Deur
die versoening van kern materiaal eienskappe soos die elastisiteitsmodulus, lang
termynewewigvog kondisies en skuifparameters, is ’n aanvaarbare gestandariseerde
voorbereidingsprotokol vir BSM-skuim en BSM-emulsie bedoel vir aanwending in industriele
laboratoriums regoor Suid Afrika suksesvol ontwikkel.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/4187 |
| Date | 03 1900 |
| Creators | Moloto, Percy Kgothatso |
| Contributors | Jenkins, K. J., University of Stellenbosch. Faculty of Engineering. Dept. of Civil Engineering. |
| Publisher | Stellenbosch : University of Stellenbosch |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | Unknown |
| Type | Thesis |
| Format | 144 p. : ill. |
| Rights | University of Stellenbosch |
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