On many sites around Geelong we find stiff basaltic clay overlaying weak sandstone beds. That contrast makes the plate load test essential for verifying design assumptions. We run PLT following AS 4678 and AS 1289. The test delivers a direct load-settlement curve. No extrapolation from N-values or correlations. Before we set up the hydraulic jack we always check the subgrade condition with calicatas exploratorias to identify any loose fill or soft patches. That step avoids misleading results. Our team has completed over 150 PLTs in Geelong alone. The city's variable geology demands site-specific data. A single PLT gives you the real modulus of subgrade reaction. That number drives slab and footing design.
A single PLT gives you the real modulus of subgrade reaction. That number drives slab and footing design.
Scope of work in Geelong
- Modulus of subgrade reaction (kₛ)
- Bearing capacity (qult)
- Settlement at working load
- Elastic modulus (E)
Typical technical challenges in Geelong
Geelong expanded rapidly in the 1960s and 1970s. Many subdivisions were built on filled former quarries and creek beds. Those fills are poorly compacted. Without a plate load test you cannot confirm the design bearing capacity. We have seen cases where assumed 200 kPa capacity was actually below 80 kPa. That difference caused slab settlement and cracking within two years. The cost of a single PLT is negligible compared to a structural failure. We also recommend PLT for pavement subgrades. Geelong's traffic loads are increasing. The Geelong Ring Road and new industrial zones require verified subgrade support. Skipping the test is a gamble.
Our services
We offer two standard configurations for plate load testing in Geelong. Both are fully compliant with Australian standards.
Static PLT – Shallow Footings & Slabs
Direct bearing test on prepared subgrade. Uses 300 mm or 600 mm plate. Measures kₛ and ultimate bearing capacity. Ideal for residential slabs, warehouse floors, and light commercial footings. Results ready within 48 hours.
PLT for Pavement Subgrades & Base Layers
In-situ modulus test on compacted subbase and subgrade. Meets Austroads pavement design requirements. Provides kₛ and E values for mechanistic design. Tested at multiple points to capture variability.
Frequently asked questions
How much does a plate load test in Geelong cost?
A standard PLT with one plate size and reporting costs between AU$1.360 and AU$2.040. Price varies with site access, number of test points, and plate diameter. We provide a fixed quote after a site visit.
What is the difference between PLT and a CBR test?
PLT measures load-settlement behaviour under a rigid plate. CBR measures penetration resistance under a piston. PLT gives bearing capacity and modulus values directly. CBR gives a relative strength index. For foundation design PLT is preferred. For pavement design both are used.
How many PLT points do I need for a residential slab in Geelong?
Typically one point per 500 m² of slab area. For variable ground at least two points. The Geelong area has known clay pockets. If you suspect fill or soft spots we recommend three points. Our engineer will advise after reviewing borehole logs.
Can PLT be performed on clay soils in winter?
Yes but results may be conservative. Wet clay softens. We prefer testing during dry periods for design values. If winter testing is unavoidable we apply a moisture correction factor based on AS 4678. Discuss with our team before scheduling.