Asphalt Mix Design & Quality Control

Mix Design

Hesselberg Hydro has a fully mobile materials laboratory equipped to conduct all essential tests on hydraulic asphalt.

Hydraulic asphalt mixtures are designed for their performance which can vary depending on the raw materials used. Thus, for each project, a separate mix design must be carried out with the available raw materials.

Mix design is carried out on-site while our laboratory in Sheffield is used for the smaller contracts.

Slight variations in the drying process between plants can affect an aggregate’s performance so it may be necessary to adjust the amount of filler or bitumen. At the selected mixing plant, our materials engineer will be present from the outset to both instruct the plant operators how to mix the materials exactly, and to check the first mixes.

Stages in mix design

• Source local raw materials
  
  
• Check suitability of aggregates – their grading and adhesion to bitumen, for instance
  
  
• Check sand and filler compatibility
  
  
• Test the trial mixes – the viscosity of mastic, and the stability / flexibility of filled mixtures, for instance
  
  
• Full scale plant trials
  
  
• Final adjustments to mix

As an additional service, our design process can be applied to asphalt mixtures supplied by other companies to our clients, such as the The Environment Agency. We also carry out mix designs on asphalts for use by other companies.

Quality Control

Following confirmation of the mix design’s suitability for transport, working and optimum end-performance, our materials engineer will concentrate on the materials’ quality control. This will ensure that, once the project is under way, the raw materials are consistent, and the final product is within specification.

Our on-site quality control laboratory is used while for smaller projects any on-site tests are backed up by our Sheffield laboratory.

Typical Quality Control Regimes

Regular analysis and monitoring is likely to be made on:

• Raw materials
• Mixing temperature
• Placing temperature
• Placed thickness
• Placed density of Dense Asphaltic Concrete
• Constituent proportions

As an additional service, quality control can be carried out for asphalt mixtures supplied by other companies to our clients, such as the The Environment Agency.