>Dear colleagues,
>
>Continued on my earlier request regarding small efficient (cold) extraction
>equipments I have three more questions dealing with the porous asphalt
>research program.
>
>The first one is on the ageing of bitumen in porous asphalt mixes in the
>laboratory. For the ageing of pure bitumen we use at the moment the RCAT
>technique and the PAV. However, essential for the ageing process is that the
>process is very similar to the ageing in practice on the road. From this
>point of view the RCAT seems to be better than the PAV. Instead of ageing
>pure bitumen we want to age mixes (cores or covered aggregates). One way
>could be the RCAT with special cylinders but there might be better devices.
>Therefore we are interested in findings of other researchers and their
>opinions about good equipment (ovens etc) and procedures for ageing of
>porous asphalt mixes in the laboratory.
>
>The second one is on measuring the layer thick nesses of the two porous
>asphalt layers in the so-called twin-layer construction. Next to the
>traditional measurements on cores (sometimes it is difficult to see the
>differences between the two layers) which we use at the moment we are
>interested in information on equipment and techniques (e.g. ultrasonic) to
>measure with an accuracy of 5 mm the layer thickness in a core.
>
>The last question is on the bonding strength between the two layers. Which
>techniques are available, known or used with some success to quantify the
>bonding strength at the interface between two porous asphalt layers (of a
>core measured in the laboratory). I can imagine that first of all there is a
>minimum diameter for the core taken out of the road. Afterwards you can
>carefully saw a test sample out of this core in order to avoid "damage".
>
>Well I hope you can help me with some information or advise with these
>questions/requests.
>
>Best regards
>Ad Pronk
>Road & Hydraulic Eng. Div.
>Rijkswaterstaat
>P.O. Box 5044
>2600 GA  Delft
>The Netherlands
>E-mail: [log in to unmask] <mailto:[log in to unmask]>
>
>
>
>
>Disclaimer
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