Structural Design of Pavements PART VI Structural ... - TU Delft

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tions should be tested in a certain section in order to obtain a realistic picture of the flexural
stiffness of the pavement.
In these lecture notes we will deal with all these aspects. The structure of the notes is as follows.
Attention will be paid to the development of a measurement program. This will be
followed with a discussion on the determination of the number of measurements required per
section and the statistical treatment of the deflection data.
Although the Benkelman beam was developed some 40 years ago, it is still in use in many
countries. This is also the case with the automated version of the Benkelman beam called the
Lacroix deflectograph. A chapter has been devoted to these devices and especially
procedures to correct the measured deflections to true deflections are discussed.
After that attention will be paid to some simple techniques allowing the overall stiffness of the
pavement structure to be assessed and potential problem layers to be identified. Then the
back calculation of stiffness moduli will be treated.
This will be followed by a discussion on the design of overlays in which probabilistic principles
are introduced.
After that ample attention will be paid to an analysis method which allows critical strains to be
evaluated without the need to back calculate layer moduli. This method is of special interest in
case accurate information on the layer thickness is not available.
Then attention is paid on the importance of visual condition surveys. A method will be
presented that allows the remaining life to be estimated from such surveys.
This chapter is followed by a chapter on the estimation of material strength characteristics like
the fatigue resistance of asphalt mixtures and the resistance to permanent deformation of
unbound granular materials.
Reflective cracking is an important issue and the commonly used overlay design methods
don’t take into account this important phenomenon. Therefore a chapter dealing with the
design of overlays controlling reflective cracking is presented.
Finally the effect of pavement roughness on pavement deterioration will be discussed and
simple procedures to estimate pavement roughness will be given.
First of all however attention will be paid to the question why pavement maintenance has to
rely on regular monitoring of the pavement condition and why the decision on applying
maintenance cannot be taken simply on the basis of the number of years the pavement is in
service or the number of loads that have been applied to the pavement.