Launceston's development as Tasmania's second-largest city dates back to its early 19th-century port origins, with rapid urban expansion pushing construction into the surrounding Tamar Valley slopes. These valley soils, often alluvial clays and weathered dolerite derivatives, demand careful compaction control from day one. Our Proctor test in Launceston determines the optimum moisture content and maximum dry density for any fill material, giving engineers the numbers they need to specify compaction targets. Before placing structural fill, we often recommend combining the Proctor result with a density test using the sand cone to verify field compaction meets the laboratory standard.
A proper Proctor curve is the cheapest insurance against settlement in fill — it tells you exactly how wet and how dense the soil must be to perform.
Methodology and scope
At an elevation of just 14 metres above sea level, Launceston's floodplain geology means much of its urban soil profile consists of silty clays and loose sands deposited by the North Esk and South Esk rivers. These materials can be highly variable within a single site, making a single compaction curve insufficient. We run the standard Proctor (AS 1289.5.1.1) for light compaction works and the modified Proctor (AS 1289.5.2.1) when projects require higher energy — typically for road subgrades and heavy-load pavements. The test itself involves compacting soil in a mould at different moisture contents, plotting the results, and reading the optimum point. For deeper foundation layers, pairing the Proctor data with a SPT borehole helps correlate compaction quality with bearing capacity across the site.
Technical reference image — Launceston
Local considerations
AS 1726:2017 Geotechnical Site Investigations requires that compaction control testing follow a documented procedure with traceable results. In Launceston, where many sites sit on reclaimed floodplain or old river terraces, the risk of non-uniform compaction is real. A poorly compacted fill layer can lead to differential settlement within months of construction. We follow AS 1289.5.1.1 for the Proctor test itself and AS 1289.5.4.1 for field density determination, ensuring every report withstands audit and supports the structural design.
5.5 lb (2.5 kg) standard; 10 lb (4.54 kg) modified
Drop height
12 inches (305 mm)
Associated technical services
01
Standard Proctor (AS 1289.5.1.1)
For light-traffic pavements, residential slabs, and general fill where compaction energy is moderate. Includes moisture-density curve and optimum moisture content report within 48 hours.
02
Modified Proctor (AS 1289.5.2.1)
Specified for high-load areas such as industrial floors, airport aprons, and heavy-haul roads. Uses higher compaction energy to simulate prolonged roller passes. Results within 3 working days.
03
On-site verification package
Combines Proctor testing with field density checks using the sand cone or nuclear gauge. We visit your Launceston site, collect samples, run the lab test, and provide a single report linking lab curve to field results.
Applicable standards
AS 1289.5.1.1 (Proctor compaction test), AS 1289.5.4.1 (Field density — sand replacement), AS 1289.5.1.1-12e2 (Standard Proctor), AS 1289.5.2.1-12e1 (Modified Proctor), ISO 17025 (Laboratory quality management)
Frequently asked questions
What is the difference between Standard and Modified Proctor tests?
The Standard Proctor applies 12,400 ft-lbf/ft³ of energy, suitable for light compaction. The Modified Proctor applies 56,000 ft-lbf/ft³, simulating heavier rollers and higher traffic loads. Engineers choose based on the design specifications of the project.
How much does a Proctor test cost in Launceston?
A single Proctor test (standard or modified) typically ranges between AU$160 and AU$320, depending on sample preparation and whether it includes a full moisture-density curve. Volume discounts apply for multiple samples from the same site.
Do you accept samples dropped off at your Launceston depot?
Yes, we accept bulk disturbed samples delivered to our lab. Please call ahead to confirm sample quantity — we need about 25 kg for a full Proctor curve. Alternatively, our technicians can collect on site.
How long does the Proctor test take from sample arrival?
Standard turnaround is 48 hours for a single Proctor curve. Modified Proctor adds one extra day due to the higher number of compaction points. We can expedite to 24 hours for an additional fee.
Can a Proctor test be performed on gravelly soils?
Yes, but we must use the 6-inch mould and a larger hammer to accommodate particles up to 19 mm. If material contains particles larger than 19 mm, we recommend a modified approach with scalping or a correction factor per AS 1289.5.1.1.
