Testing of road bitumen and mineral powder

Why bitumen is tested

• incoming inspection of the received bitumen batch
• verification of compliance with the supplier's quality certificate
• asphalt mix design
• assessment of bitumen performance under specific climatic conditions
• independent verification of results from the plant laboratory
• resolution of disputes between the client and the supplier

What the bitumen indicators show

Penetration of the needle characterises the consistency of bitumen at a specified temperature and serves as the basis for assigning the grade.

Softening point shows the temperature at which bitumen transitions to a flowable state. It affects the resistance of the pavement to heat.

Ductility assesses the ability of bitumen to elongate without rupture — essential for the crack resistance of the pavement.

Brittle point defines the minimum service temperature at which bitumen does not yet crack.

Mass loss after heating shows the loss of volatile components and the ageing of bitumen.

Adhesion to mineral materials characterises the ability of bitumen to remain on the surface of crushed stone and sand grains after exposure to water.

Conventional viscosity is used to assess liquid and viscous bitumens at process temperature.

Why mineral powder is tested

• incoming inspection of a batch at the asphalt plant
• confirmation of compliance with the supplier's documents
• asphalt mix design
• assessment of the stability of raw-material quality
• estimation of asphalt concrete durability under moisture exposure

What the mineral powder indicators show

Grading defines the size distribution of the powder particles and their role in filling the voids of the mineral skeleton of the mix.

Average and true density are used to calculate the mass and volume of the powder in the mix design.

Porosity characterises the internal structure of the powder and affects the amount of bitumen required for the mix.

Swelling of the powder-bitumen mix shows the behaviour of the "powder + bitumen" system upon contact with water.

Water resistance confirms whether the mix retains its properties after exposure to water.

Hydrophobicity characterises the ability of the powder to repel water and retain the bond with bitumen under humid conditions.

Applicable standards

For road bitumen, GOST 33133-2014 applies — requirements for viscous road bitumens; the test methods are specified in separate interstate standards.

For mineral powder — GOST 32761-2014 — requirements for mineral powder for asphalt concrete and organo-mineral mixes.

Russian GOST R and PNST standards are not presented as norms of Uzbekistan and are applied only on a separate project basis.

Deliverables for the client

Based on the results of the work, MATTEST issues a test report with batch identification, the applied method, actual indicators and comparison with the specified requirements.