Compaction testing and CBR testing for earthworks

We determine the appropriate laboratory testing required for your project based on the design, construction requirements and applicable standards. Testing is coordinated through our NATA-accredited laboratory partners, with the resulting data reviewed and interpreted by our geotechnical team to assess compliance with the project requirements.

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What we cover

Compaction testing. Field density testing of placed fill and earthworks to verify that the required level of compaction has been achieved. Testing frequency, acceptance criteria and test locations are determined by the relevant project specifications and the infrastructure being constructed, including roads, stormwater, sewer and watermain works.

CBR testing. California Bearing Ratio (CBR) testing of subgrade and pavement materials in accordance with AS 1289.6.1.1, providing an assessment of the material's strength and resistance to penetration for use in pavement design and assessment.

Material classification and assessment. Laboratory testing including particle size distribution, Atterberg limits, linear shrinkage and moisture content in accordance with the applicable AS 1289.3 series methods. This testing assists in classifying materials and determining their suitability for the proposed earthworks and infrastructure applications.

Moisture density relationship. Laboratory compaction testing to establish the maximum dry density and optimum moisture content of nominated materials. Testing is undertaken in accordance with the applicable AS 1289 series methods, providing the reference values required to assess field compaction results.

Level 1 earthworks inspection and testing. Earthworks inspection and testing undertaken in accordance with AS 3798, including Level 1 inspection, supervision and testing. This provides documented verification of fill placement, material suitability, moisture conditioning and compaction throughout the earthworks process.

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How we run testing

Testing runs through NATA accredited laboratories. We scope the testing your specification requires, choose where and when to test, manage the sampling and the logistics, and read the results against the specification and the design.

We work with two NATA accredited laboratories and choose between them by where the project is. We collect the samples, prepare the chain of custody and test request, deliver them to the laboratory and receive the reports by email.

You get one point of contact, one report and one invoice.

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When you need it

Bulk earthworks. Cut and fill operations associated with subdivisions, civil developments and building platforms.

Trench backfill. Compaction and material assessment for stormwater, sewer, watermain and other service trenches.

Subgrade and pavement construction. Testing and assessment of road and car park subgrades, pavement materials and completed layers.

Building pads and controlled fill. Compaction and earthworks testing for building platforms and controlled fill beneath slabs, in accordance with AS 2870 Section 6 and AS 3798, where applicable.

Borrow pit assessment. Assessment and laboratory testing of proposed borrow materials to determine their suitability before extraction, haulage and placement.

Retaining wall backfill. Material assessment and compaction testing of backfill placed behind retaining structures.

Conformance testing. Verification testing undertaken where required by the relevant council, superintendent, engineer or project specification prior to acceptance or sign-off.

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Controlled fill under a slab

Under AS 2870, sites containing fill are classified as Class P. Where the fill has been placed as controlled fill, in accordance with the relevant requirements of AS 2870 and AS 3798, footings can generally be founded within the controlled fill, subject to the requirements of the structural and geotechnical design.

Controlled fill is placed in nominated layers, compacted to the specified density and progressively tested to verify that the required compaction has been achieved.

Where fill is uncontrolled, it cannot be relied upon as a suitable founding material for conventional footings. In these circumstances, footings generally need to extend through the uncontrolled fill and be founded into suitable natural ground, or an alternative foundation solution may be required.

If you are placing fill on a residential lot, arrange testing progressively as the fill is placed. This provides the necessary evidence to establish whether the fill has been constructed as controlled fill and can subsequently be relied upon for footing design.

Site classification, AS 2870

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What you get

A project-specific testing schedule. Testing requirements and frequencies aligned with the relevant project specifications and the infrastructure being constructed, rather than a generic testing package.

Field density results. Compaction results recorded progressively throughout the works and assessed against the nominated compaction requirements.

CBR and material classification results. Laboratory results provided with the applicable test methods and relevant material properties clearly identified.

Clear compliance assessment. Test results assessed against the applicable project specifications, with any non-conforming results clearly identified and reported.

Conformance reporting. Clear documentation of inspection and testing outcomes suitable for submission to the superintendent, engineer, certifier or council, as required by the project.

Certification where required. Relevant certification or professional sign-off provided where required by the project approval, specification or regulatory authority and within the applicable professional scope.

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Common questions

It depends on the volume of fill, how many layers need testing, the site location and the turnaround. Send the earthworks specification and the extent of fill and we will come back with a fixed price.

Sizing pavement layers. The CBR value describes how much load the subgrade can carry, and the pavement designer uses it to work out how thick the base and sub-base need to be.

Yes. Where a residential site involves new fill, we can coordinate both services as part of the same project. Compaction testing is undertaken progressively as the fill is placed to verify that it has been constructed in accordance with the required specifications. Once the earthworks are complete, the site classification can then be undertaken using the available earthworks and testing records to assess the completed site in accordance with AS 2870.

The specification usually sets it, by volume or by layer. Where it does not, we scope it against AS 3798 and the conditions on the job.

Field density results come back faster than laboratory CBR and moisture density work. Tell us the programme when you book and we will schedule the sampling around it.