Sustainable Pavement Overlays: Part Ii. Shear Performance of Composite Beams on Elastic Foundation and Their Numerical Representation

Shear conditions were set up to study the reflective cracking caused by rocking and pumping effects over weak supports as part of the Green Overlays research programme.
It was anticipated that any up-to-date attachments to the behaviour of steel fibre reinforced, polymer modified, roller compacted and bonded composite beams resting on elastic foundations can be significant to both research and practicing community. They can make a notable contribution to reducing repair costs and can increase safety and confidence of the road users.
The behaviour of specimens on the foundation resembled closely those under single-notch-shear-beam-tests in earlier studies by the same authors and confirmed that the overlaid steel fibre reinforced, polymer enriched, roller bonded material succeeded in keeping cracking under control.
A good agreement was obtained between measured and predicted results. The finite element method depicted well the real behaviour of beams, with hairline cracks appearing and propagating, and resembling closely, laboratory performance. Numerical analysis continued to predict the generation and spreading of cracks well beyond laboratory limitations. These cracks propagated towards the loading position, while gradually more fine cracks appeared in the vicinity of the notch.
It was revealed that the notch tip displacement was effectively controlled by the fibre bridging capacity in the overlay.
It was shown that, increasing overlay thickness can effectively reduce the susceptibility to shear failure and subsequent reflective cracking and minimise differential displacement at underlying joints, or cracks.
It has been established that the fibre bridging effect in conjunction with the enhanced mechanical properties of polymeric overlays, have a significant advantage over its plain concrete rival in controlling the deformation and stress concentration at a crack tip.