Asphalt sampling for PAH testing: quantity, layers and laboratory shipping

The quality of PAH testing depends first and foremost on the representativeness of the sample. BJL's currently published Rev.22 sample submission form specifies a minimum mass of 200 g for PAH testing. The asphalt layers must be identified and separated where necessary.

Confirm the shipping requirements

How much asphalt should be sent?

BJL's Rev.22 sample submission form specifies a minimum mass of 200 g for PAH testing. This quantity should be understood as the published minimum requirement; a larger quantity may be necessary depending on the form of the sample, the number of layers or the requested services.

Why should the layers be separated?

A road core may contain several materials laid during different roadwork campaigns. An older layer may have a different composition from a more recent surface course. If the layers are mixed, the result may not accurately represent the area that must be managed separately.

The BJL form states that the layers to be tested must be specified. If in doubt, include a photograph and indicate the approximate thickness of each layer.

How should the sample be identified?

• assign a unique reference to each core or sample;
• state the location of the sampling point;
• describe the number of visible layers;
• specify the layer or layers to be tested;
• use the same reference on the packaging and sample submission form;
• include the file or purchase order number.

Should the asphalt be crushed before shipping?

Previously published BJL documents asked clients to separate and crush the layers to be tested, whereas the current Cofrac accreditation scope describes laboratory pretreatment consisting of crushing to below 4 mm, homogenisation and quartering. To avoid any ambiguity between layer separation and analytical pretreatment, follow the latest BJL quality sample submission form and contact the laboratory before carrying out any irreversible preparation of the core.

Packaging and transport

The packaging must preserve the identity of the sample and prevent material loss and cross-contamination. Use robust, sealed and clearly labelled packaging. When asbestos testing is also required, the asbestos-specific packaging rules take priority.

Prior asbestos testing

BJL's currently published terms and conditions require an asbestos testing report for the asphalt, issued by an accredited laboratory, before PAH testing. If asbestos is confirmed, PAH testing is not carried out. If the project must address both issues, see our page on asbestos and PAH testing in asphalt.

What should be sent with the sample?

• the current BJL sample submission form;
• the project or file reference;
• the client's contact details;
• the list of samples;
• the layers to be tested;
• the prior asbestos report where required;
• the requested turnaround time and any particular constraints.

Common mistakes to avoid

• sending a core without a reference;
• mixing several non-homogeneous sampling points;
• failing to specify the layers;
• sending an insufficient mass;
• requesting PAH testing without providing the asbestos documentation required by BJL's conditions;
• preparing or crushing the sample without first checking the current quality instructions.

Frequently asked questions

Is 200 g always sufficient?

Two hundred grams is the minimum mass published for PAH testing in the Rev.22 form. If the sample contains several layers or several services are required, confirm the quantity with the laboratory.

Can several cores be sent in the same parcel?

Yes, provided that each sample is packaged and identified unambiguously and that the sample submission form clearly links each reference to the requested analysis.

Is sampling covered by the PAH accreditation?

The PAH scope described here covers the laboratory testing of bituminous asphalt waste. The representativeness of on-site sampling remains the responsibility of the sampling procedure used for the relevant project.