DIGEST 2006 - Sabita

itumen emulsion or foamed
bitumen, offers a feasible and cost
effective solution to the problem of
providing sustainable pavement
design solutions. However, this
challenge is not without obstacles,
and most significant of these is the
lack of sound and practical
guidelines to the design and use of
bitumen stabilised materials.
Structured experience
Inadequate guidelines have
resulted mainly from the lack of
structured and documented
experience related to the design,
use and performance of bitumen
emulsion and foamed bitumen
materials.
To address these issues, Sabita, in
conjunction with the Gauteng
Department of Public Transport,
Roads and Works (GPTRW),
initiated a project to develop
updated guidelines on the design
and use of Bituminous Stabilised
Materials (BSM).
This initiative aims to incorporate
both emulsion and foamed
bitumen materials in a single BSM
guideline to promote rational
materials selection and equitable
competition between the two
material types. This guideline will
update the technology presented
in current guidelines for these
materials (e.g. TG2 – Interim
Technical Guidelines: The design
and use of foamed bitumen
treated materials, Sabita Manual
14: GEMS – The design and use of
granular emulsion mixes, and
Manual 21: ETB – The design and
use of emulsion treated bases.)
The Project
The project to develop a guideline
for the design and use of
bituminous stabilised materials
was initiated in early 2005. At the
outset, it was recognised that the
structural design and mix design
elements of the existing guidelines
required the most urgent and
significant improvements. The
project was therefore structured to
address these two aspects in a
comprehensive manner. Owing to
the ambitious scope of the project,
it was structured to allow
execution in distinct phases, as
shown in Figure 2.
The mix design element of the
project is being undertaken by
Professor Kim Jenkins of the
University of Stellenbosch, while
the Structural Design element is
being handled by Drs. Fritz Jooste
and Fenella Long of Modelling and
Analysis Systems (MAS).
As shown in Figure 2, the second
phase of the project is currently in
progress, and the bulk of this work
is scheduled for completion in
early 2008, at which time the
compilation of the guidelines will
begin.
Mix Design Developments
The mix design component of this
study aims to identify the
inadequacies in current
approaches to foamed bitumen
and bitumen emulsion mix design
procedures, and to explore
laboratory test protocols and
available laboratory test data for
these materials that would provide
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