RPRAC WORKING GROUP: THIN-LAYER CONCRETE RPF, 23 November 2005

1. RPRAC WORKING GROUP: THIN-LAYER CONCRETE RPF, 23 November 2005

2. Working Group Research Needs Current Projects Funding Proposals

3. 1. Working Group 1. Pieter Strauss 2. Louw Kannemeyer - SANRAL 3. Bryan Perrie - C&CI 4. Rudi Kuhn - CSIR 5. Alex Visser - UP 6. P W de Bruin - Tshepega 7. Elzbieta Sadzik - Gautrans 8. Rolf Beger – RBPM 9. Others, any volunteers

4. 2. Research Needs 1. Modelling under loads 2. Modelling of crack spacing 3. Shrinkage effects 4.  Environmental effects 5. Maintenance and repair 6. Prediction of performance including monitoring

5. 2. Research Needs (Cont) 7. Bond and/or anchoring to supporting layers 8. Constructability and Variability 9. Loss of support 10.  Life-cycle costing 11. Crack/joint movement and deflection measurement 12. Comparison of accelerated test sections and LTPP sections

6. 3. Current Projects 1. Roodekrans,50 mm “CRCP “ 2. Umtata, 50 mm “CRCP” 3. Mpumalanga, 50 mm “CRCP” Ash 4. Heidelberg - Louw Kannemeyer

7. 3.1 Roodekrans,50 mm “CRCP “ The Philosophy Behind The Roodekrans Project Construction of an experimental access road to a major quarry, All the trucks leaving the quarry went over a weighbridge and were accordingly counted and weighed, CSIR constructed three sections of CRCP 50mm, 75mm and 100mm thick .

8. PAVEMENT DESIGN 50mm CRCP (200x200x6mm mesh) 50mm ETB (normally 100mm) 125mm Stabilised gravel subbase in situ compacted gravel (Standard 19mm (13mm preferred) 30 MPa/28 day Colto specification concrete)

9. CONSTRUCTION OF THIN CONCRETE PAVEMENT (note ETB base)

10. CONSTRUCTION OF THIN CONCRETE PAVEMENT (note ETB base)

11. CONCLUSIONS The performance of the 50mm thick (thin) mesh reinforced concrete was exceptionally good having carried approximately 500 000 E80’s and is still in good serviceable condition, To date, there are no centre line cracks on the concrete slabs despite the tracking of the heavy vehicles (Cracking on the centre line would have occurred had “curling” been a problem, The performance to date indicates that it is possible to lay mesh reinforced 50mm thick 30 MPa concrete successfully without joints for low to medium volume roads (including Urban Streets), Technology labour intensive and in support of ECD.

12. 3.2 Umtata, 50 mm “CRCP” Community access road to quarry Similar to Roodekrans 2,5km Labour based CRCP 1km Labour based seals 5. Various trial sections

13. 3.3 Mpumalanga, 50 mm “CRCP” Ash 1. 50 mm “CRCP “ utilising ash as aggregate 2. 14m test section to be constructed and tested at University of Pretoria 3. Test section half 30Mpa concrete/ash concrete 4. Trial Section to be constructed in Mpumalanga

14. 4. Funding Proposals Application joint research CSIR/University of Pretoria Research on thin Reinforced Concrete Pavements Research to be conducted in laboratory and on site (Umtata & Mpumalanga) Funding requirement R 2 million (CSIR co-funding 400k)

15. 4. Funding Proposals (Cont) Research includes Establishment of the actual load-deflection behaviour of three sections at Roodekrans Various trial sections at Umtata and Mpumalanga Supplemented by testing slabs in the laboratory to cover the range of properties expected during design Development of a standard method to design thin steel reinforced concrete pavements

16. Thank You