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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. JangayaMoi University
DelftTU
Introduction DelftTU
• 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
• 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.
DelftTU
Introduction DelftTU
• 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 DelftTU
• 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? DelftTU
• 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
• 2010 IEK Conference
• Why the literature survey?
– Clauses from the draft.
– to make objective & informed decision(s) for
adoption/adaption.
DelftTU
German design procedure
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
DelftTU
Dutch design procedure DelftTU
Traffic loadings: Axle loads, Directional factor, Design traffic lane,
Substructure: Modulus of substructure reaction
Concrete:
Strength Parameters, Elastic modulus
Traffic load stresses:
Load transfer at joints,
Westergaard equation
Temperature gradient stresses: Eisenmann/Dutch method
Concrete slab thickness: Miner fatigue analysis
Climate: Temperature gradients
Adaptability to Kenya
• Parameters considered, include:
– traffic loadings;– temperature gradients (climate); – concrete grades; – Characterization of substructure;
DelftTU
Conclusion
• 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)
DelftTU
Conclusion
• Dutch “better” addresses:
– overloaded trucks,
– temperature variations – what’s required,
– concrete grades
• German “better” addresses:
– characterization of the substructure
DelftTU
Issues
• Do we need monitoring program for Mb. W
• Any challenges with Mbagathi Way
• Progresses with the design codes.
DelftTU
Appreciation & Acknowledgement
IEK Conference organising committee
VLIR-UOS MU-K CSE project
Moi University
Session & programme chair
DelftTU
END!!
Thanks
DelftTU
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