Transcript - The Institution of Engineers of Kenya

TU Delft
IEK INTERNATIONAL CONFERENCE
Theme: The Role of Engineering Practitioners
in the Implementation of the Constitution
Title: An Assessment of the Adaptability of
Empirical & Mechanistic Design
Procedures for PCPs in Kenya
P. O. Jangaya
Moi University
Introduction
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• Generally, CC roads are associated with
high initial construction costs, and low cycle
costs compared to AC roads.
• Types of CC? “cheapest”.
• As at “1st ¼ of 2010”, cement concrete roads
constituted approximately 0.002 % of
Kenya’s road network – Mbagathi Way, NRB
Introduction
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• CC design procedures: Empirical,
mechanistic & mechanistic-empirical.
– Empirical: based on long term experience with
concrete roads -> adequate experimental data.
– Mechanistic: based on mathematical models of
material behaviour and determination of
stresses within the structure -> ‘new’ countries.
Introduction
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• Practice
– Empirical: e.g. Germany (described by RStO
01 (2001) & revised after every 10 years),
Austria and Belgium.
– Mechanistic: e. g. the Netherlands, South
Africa, and Canada.
. Major works done at Mbagathi Way, BUT
not first one.
Mbagathi Way in brief
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• Approx. 3 km long, built in 2006 – 2007
• Design done based on
S.A. design procedure
• 210 mm thick DJPC
pavement done by
Kabuito Contractors Ltd
What next after REHAB?
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• Monitoring program?
• Development of own design code?
– Evident in draft from Ministry of Roads in
2009
– In this document, -- a lot of borrowing from
what is already available from other countries
especially from South Africa.
– Why the heavy borrowing?
– Any progress on this draft?
My contribution
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• 2010 IEK Conference
• Why the literature survey?
– Clauses from the draft.
– to make objective & informed decision(s) for
adoption/adaption.
German design procedure
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Alternative designs of CPs for German expressways for heaviest
traffic loadings and a frost-proof pavement structure of 900 mm:
(1) concrete pavement on cement-bound base (2) concrete
pavement on geotechnical fabric and cement-bound base (3)
thick concrete pavement on crushed aggregate base
Dutch design procedure
Traffic loadings:
Axle loads,
Directional factor,
Design traffic lane,
Substructure:
Modulus of
substructure
reaction
Traffic load stresses:
Load transfer at joints,
Westergaard equation
Concrete:
Strength
Parameters,
Elastic modulus
Climate:
Temperature
gradients
Temperature gradient
stresses: Eisenmann/Dutch
method
Concrete slab
thickness: Miner
fatigue analysis
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Adaptability to Kenya
• Parameters considered, include:
– traffic loadings;
– temperature gradients (climate);
– concrete grades;
– Characterization of substructure;
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Conclusion
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• Kenya, just starting to appreciate use of
CC, needs:
– design procedure which allows the use of a
country’s nationally determined parameters
for inclusion in its models
– procedure should also be one that does not
require a lot of field data (experience)
Conclusion
• Dutch “better” addresses:
– overloaded trucks,
– temperature variations – what’s required,
– concrete grades
• German “better” addresses:
– characterization of the substructure
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Issues
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• Do we need monitoring program for Mb. W
• Any challenges with Mbagathi Way
• Progresses with the design codes.
Appreciation & Acknowledgement
IEK Conference organising committee
VLIR-UOS MU-K CSE project
Moi University
Session & programme chair
TU Delft
TU Delft
END!!
Thanks