Van Asbeck Apparatus for Flexibility Test on Hydraulic Bituminous Mixes

The apparatus consists essentially of a steel cylindrical cell divided in two sections:

• the upper part that is the under pressure water container
• the lower part consisting of a cone with opening in the lower end.

These two parts are clamped together by two flanges (upper and lower) with the interposition of a 50 cm ID steel ring which contains the compacted bituminous sample. The lower conical part  has to be filled by 2-2.5 mm  dia. of glass spheres which support the compacted 50 cm diameter slab when it is subjected to 3 bar water pressure.

The  valve of the lower conical end is then opened and the glass spheres are removed at a rate of 250 g every 15 minutes to a total of 5 kg, thus forming a hollow space under the slab to a maximum depth of 5 cm.

The water pressure is then maintained for another 5 hours. The asphalt slab should remain impervious during this
flexibility test, even is fine surface cracks develop in the bottom of the slab.

The apparatus includes:

• Steel cylindrical cell
• Air pressure regulator
• Safety valve
• Series of inlet/outlet/water discharge /overflow valves
• Manometer
• Level indicator
• Confining steel ring with shaped steel plate for sample compaction preparation
• Overflow/water filling/ water discharge valves
• Air/Water pressure cylinder
• Sealing material
• 20 kg of 2-2.5 mm dia. glass spheres

The apparatus require compressed air. For a suitable air compressor, please refer to the accessories section.