Thesis (MScEng)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: Factors influencing surface run-off of bitumen emulsions were studied in order to understand
binders for use in the construction of surfacing seals.
Run-off of the binder from the road surface causes an inconsistent film thickness leading to
ravelling (Johannes, Hanz & Bahia n.d.) and bleeding at the upstream and downstream
regions, respectively.
There is currently no accepted specification for surface run-off viscosity. Practice mainly
relies on empirical tests and experience. As the establishment of such a specification
encompasses performance of the binder in various environments or field conditions, this
study was undertaken to determine performance of the selected binder. Viscosity was kept
constant by spraying the emulsion at a constant temperature and also holding the pavement
temperature constant.
In order to study the run-off behaviour of the binder, run-off tests were conducted at various
gradients, texture depths and spray rates. Surfacing seals of various texture depths were
constructed in the laboratory. Using a spray bar, the emulsion was sprayed at various spray
rates. The sample surfaces were tilted to various gradients.
Results portrayed the effects of the three factors (spray rate, gradient and texture depth) on
the amount of runoff. An increase in the magnitude of the factors resulted in a variation in the
runoff (increase or decrease). One notable finding was that the runoff from the 9.5 mm seal
was less than that from the 13.2 mm seal. The other significant finding was that spray rate
had the largest effect on runoff, followed by texture depth, and gradient. / AFRIKAANSE OPSOMMING: Sekere eienskappe wat oppervlakdreinering van bitumen emulsies op paaie beinvloed, is
bestudeer om sodoende binders wat gebruik word in die konstruksie van die seëls beter te
verstaan.
Afloop van die binder vanaf die padoppervlak kan lei tot die vorming van ‘n laag met
ongelyke dikte wat moontlike rafeling (Johannes, Hanz & Bahia nd) en bloeing vanuit die
onderkant van die pad tot gevolg kan hê.
Daar is tans geen aanvaarde spesifikasies wat hierdie verskynsels inperk nie. Konstruksie
praktyk berus hoofsaaklik op empiriese toetse en ondervinding. Hierdie studie is dus
onderneem om prestasie van die geselekteerde binder vas te stel. Viskositeit was konstant
gehou deur die aangewende emulsie en padtemperatuur konstant te hou.
Ten einde die afloopgedrag van die binder te bestudeer, is toetse uitgevoer op verskeie
hellings, tekstuurdieptes en aanwendingskoerse. Seëls van die verskillende tekstuurdieptes
is gebou in die laboratorium, en emulsies op hierdie oppervlaktes aangewend. Die
toetsoppervlakte is gekantel om die vereiste helling te kry.
Resultate vir die drie faktore wys die invloed op afloop. ‘n Toename in die grootte van die
faktore het gelei tot 'n variasie in die afloop (toename of afname). Een noemenswaardige
bevinding was dat die afloop van die seël van 9,5 mm minder was as dié van die seël van
13,2 mm. Belangrike bevindinge sluit ook in dat die spuitkoers die grootste invloed het op
afloop, gevolg deur die tekstuur diepte en die gradiënt.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/80366 |
| Date | 03 1900 |
| Creators | Kashaya, Asiimwe Annie |
| Contributors | Jenkins, K. J., Rudman, C., 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 | xv, 157 p. : ill. |
| Rights | Stellenbosch University |
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