Standards Development

Scope

This document specifies test methods for determining the resilient (recoverable) and accumulating permanent (nonrecoverable) deformation behaviour of unbound materials including unbound mixtures as defined in EN 13285 under conditions that simulate the physical conditions and stress states of these materials in pavement layers subjected to moving loads. These procedures enable the determination of mechanical properties that can be used for performance ranking of materials and for calculating the structural responses of pavement structures.

The test methods are applicable to cylindrical specimens of unbound materials prepared by laboratory compaction. A maximum particle size is defined so as to allow, as far as possible, a representative assessment of the response of the whole material without undue influence of the largest particles.

Procedures are provided for:

measuring the resilient properties of unbound materials by the application of cyclic loading;

measuring the permanent deformation accumulating in unbound materials by the application of cyclic loading.

For either procedure, loading of the specimen can be selected from one of two methods:

method I: the constant confining pressure method in which cyclic axial loading is carried out at constant cell pressure;

method II: the cyclic confining pressure method in which the cell pressure is cycled in phase with the axial load.

Using method I, a procedure is also provided for measuring the permanent deformation accumulating under the application of cyclic loading for each of a sequence of stress paths.

Purpose

Text has been simplified, consistency provided where previously there were internal conflicts, wording is now more precise appropriate for a standard, requirements have been updated to reflect current equipment manufacture and experience. The latter means that the obligation to use particular manufacturer equipment arrangements has been removed.