Basic characteristics of the design:

• Design optimized with the geometry of the slab and position of the loads of heavy vehicles.
• Granular base (with less than 8% fines), asphalt base, cement treated base, old deteriorated asphalt pavements.
• Geo textile between sub grade and base
• Thin joints (2 mm thick)
• No sealing
• No tie bars nor dowel bars (except for very heavy loads and construction joints)

Pavements Thickness:

• Urban Streets: 8 – 12cm
• Rural roads: 12-15 cm
• Highways: 15 – 20 cm

Normally, on 3.5 to 5 meters long slabs, the front and rear axles apply the load simultaneously at both edges of the slab. This loading induces the traffic surface tensile stresses on the top of the pavement when it is curled upwards, inducing top down cracks. These tensile stresses at the top are due to the moment produced in the cantilever part of the slab. This moment and stresses are smaller for shorter slabs, as the cantilever is shorter. In this situation, the load transfer is very important as it allows more than one slab to take the load.

If the slabs are short, of a length where the front and rear axles will never load the edges simultaneously (Figure 1), the configuration of the loading and the rocking of the slabs change the stresses configuration within the slab. Only one set of wheels will move over the slab and the slab will rock in a way that the load will always be touching the ground, therefore well supported. In this case the slab will have no stresses produced by the cantilever and the loading. In rocking, the slab will be lifted and the weight of the slab will induce tensile stresses at the surface (Figure 1). Now, the stresses are produced by the slab’s own weight when it rocks. The main loading for top tensile stresses will depend on the geometry of the slab and not on the traffic loading. If the slabs are curled upward and allowed to rock, the stresses will be reduced, assuming the stiffness of the base is optimal.

The following is a finite element analysis of the principal described above:

• Thickness: 20 cm of concrete
• Loads 1500 kg on each side