Pavement Concepts > Joint movement

The variable joint movement in the program will only be of interest when an old pavement is evaluated. Joint movement on pavements that have been trafficked for some time is usually determined through Falling Weight Deflectometer (FWD) measurements.

New pavements will initially not show any relative vertical movements and therefore load transfer C, a function of relative vertical movement under loading at joint/crack, is considered in the program as a function of (3):

For steel bars: For aggregate interlock:

where

Pd the load on steel dowel/bar as a result of wheel loading (kN),

dia steel diameter (mm),

E1 stiffness of the concrete (MPa),

Dx crack width, and

Agg diameter of 15 % largest aggregate in the concrete mix.

It can be accepted that in a pavement with void below the slab, a certain amount of relative vertical movement will be necessary at a joint/crack before load transfer occurs. This is especially true for pavements that have been in use for some time. Practical measurements in the field have indicated values of between 0.05 mm and 0.25 mm for jointed pavements, 0 mm to 0.08 mm for doweled pavements, and 0 mm to 0.007 mm for continuously reinforced pavements.

An important note: Please remember that the deflection reported by cncPAVE results from the applied distribution of axle loads - see the Axle Loads Page. Should you wish to simulate the deflection or relative vertical movement at a joint or crack under a single load, e.g. the 40 kN usually applied by the FWD, do the following:

Go to the Axle Loads Page. Set the k-factor to 1.0. Select Other traffic situation. Enter 0 into the field for all axle load frequencies. Enter 34 into the field for 7.5000 t and enter 66 into the field for 8.5000 t. Save all changes. The graph will automatically be updated. Check that the value of E80/ax printed in the graph's footnote is 1. Click the tab of the Control Page, make sure that the constant Axles/HV is 2.0 and run the process.