Accelerated performance testing of concrete pavement with short slabs

Abstract

A new concept for designing concrete pavements by optimising the slab geometry in order to reduce the slab thickness as well as to minimise the mechanical load transfer devices has recently been proposed. Theoretically, the reduced slab size lowers the load and curling-induced tensile stresses and concomitantly a thinner concrete slab can be constructed. Full-scale test sections were constructed and tested under accelerated pavement loading conditions to validate this design concept hypothesis. The design and concrete material factors studied in this research were concrete thickness of 9, 15 or 20 cm; granular or asphalt concrete base layer; and plain or fibre-reinforced concrete (FRC). A methodology was presented to convert the channelised traffic loading to equivalent single axle loads (ESALs) so that comparisons could be made between the various test sections. The accelerated pavement testing showed that shorter slab sizes can sustain a significant number of overloads and greater number of ESALs before developing cracking relative to standard jointed concrete pavements. The most prevalent distress observed was corner cracking which occurred twice as much as longitudinal cracks, whereas only 3 out of 46 cracking distresses were transverse cracks. The 20 cm concrete slabs on granular base did not experience fatigue cracking for trafficking up to 51 million ESALs. The 15 cm concrete slabs on granular base began cracking on an average of 11 million ESALs. As expected, the concrete slabs on asphalt base resisted a significant larger number of ESALs relative to the same concrete thickness on granular base. The cracking performance of the 9 cm concrete slabs on granular base varied with the stiffness of the soil. For the 9 cm slab thickness, structural fibres provided a longer fatigue life and extended service life relative to the plain concrete slabs. Finally, the smaller slab sizes maintained a medium-to-high load transfer efficiency over the accelerated loading period for all slab thicknesses without the development of any faulting. As expected, these slab systems resulted in higher deflections, and, therefore, the granular base and subgrade layers as well as lateral drainage system must be designed and specified to reduce the rate of permanent deformation and minimise the possibility of support erosion.

Keywords:

• concrete pavements
• short slab geometry
• full-scale testing
• accelerated testing

Acknowledgements

The authors would like to acknowledge TCPavements Ltd. for their financial support of this research. TCPavements is patented technology in Chile (44820-2009), the USA (757,1581) and international application PCT/EP2006/064732. The contents of this report reflect the view of the authors, who are responsible for the facts and accuracy of the data presented herein.