Influence of the Binder Coverage of Mineral Aggregates on the Mechanical Properties of the Bituminous Mixtures, (VSS1999/128)
Overview
Background & policy context:
The dissociation of the binder from mineral aggregates is causing several kinds of damages. According the Swiss standard SN 640'925, typical damages are:
- Loss of material, deterioration of the surface
- Cracking, due to weakness of adhesion combined with mechanical stress
- Potholes
- Insufficient interlayer adhesion and blister formation
In case of extended dissociation the bearing capacity of the layer is lost
The standardized procedure to determine the coverage of aggregates in Switzerland (SN 671'960) should be validated. Mixtures having a good defined coverage are produced The specimens are on the one hand immersed in water at specified conditions and finally tested mechanically, on the other hand directly tested. This allows determining the water sensitivity, which can be correlated with the coverage.
Objectives:
The objective is to provide determination of the critical coverage below that mechanical strength will be insufficient. Furthermore it is planned to provide evaluating a proposal for a specification regarding coverage.
Methodology:
This part describes the tests carried out. Can be applied, since the examinations provided in very different degrees to be known and also carried out very specifically geared partly to this research their use, they are presented in different level of detail. In the extreme case, reference is made to the relevant standard. It is therefore selected a three-part description, the individual parts are inserted as needed:
- Motivation: Where sense explains why this test has been applied and what is expected of her.
- Description: This description pointing to the standard, possibly supplemented by information on modifications of the process. In little-known testing a full test description is given.
- Review: Some procedures were only preliminary at already there showed that the objectives cannot be achieved.
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