1. 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

2. Introduction Generally, CC roads are associated with high initial construction costs, and low cycle costs compared to AC roads. Types of CC? “cheapest”. As at “1 st ¼ of 2010”, cement concrete roads constituted approximately 0.002 % of Kenya’s road network – Mbagathi Way, NRB

3. 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.

4. Introduction 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.

5. Mbagathi Way in brief 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

6. What next after REHAB? 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?

7. My contribution 2010 IEK Conference Why the literature survey? –Clauses from the draft. –to make objective & informed decision(s) for adoption/adaption.

8. 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

9. Dutch design procedure 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

10. Adaptability to Kenya Parameters considered, include: –traffic loadings; –temperature gradients (climate); –concrete grades; –Characterization of substructure;

11. 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)

12. Conclusion Dutch “better” addresses: –overloaded trucks, –temperature variations – what’s required, –concrete grades German “better” addresses: –characterization of the substructure

13. Issues Do we need monitoring program for Mb. W Any challenges with Mbagathi Way Progresses with the design codes.

14. Appreciation & Acknowledgement IEK Conference organising committee VLIR-UOS MU-K CSE project Moi University Session & programme chair

15. END!! Thanks