Rigid pavement design in Geelong must comply with AS 1726:2017 for geotechnical site investigations and Austroads pavement design guidelines. Geelong's geology transitions from Quaternary basalts on the Bellarine Peninsula to Quaternary alluvial sands along the Barwon River, creating very different subgrade conditions within short distances. A rigid pavement relies on the concrete slab's flexural strength to distribute traffic loads, so knowing the subgrade's modulus of subgrade reaction (k-value) is critical. For projects near the waterfront or on former industrial land, we often combine the rigid pavement analysis with a geotechnical drainage study to control moisture beneath the slab, and a plate load test to validate the k-value in situ before pouring concrete. This integrated approach prevents premature cracking and joint faulting.
A rigid pavement's service life depends more on subgrade uniformity and drainage than on concrete strength alone — a lesson learned in Geelong's variable alluvial soils.
Scope of work in Geelong
Typical technical challenges in Geelong
Geelong's urban expansion since the 1950s has pushed development onto former wetlands and reclaimed areas along Corio Bay and the Barwon River floodplain. These soft, compressible soils pose a serious risk for rigid pavements: differential settlement under the slab leads to corner cracking and stepped joints. Additionally, the region's shallow water table (often <2 m depth in low-lying suburbs like Newcomb and Whittington) can cause pumping of fines through uncracked joints, eroding subgrade support. Without a proper rigid pavement design that accounts for these conditions — including a drainage layer and a separation geotextile — the pavement may need major rehabilitation within five years. The risk is compounded by heavy truck traffic servicing the port and the Geelong Ring Road.
Our services
Our rigid pavement design services in Geelong cover the full scope from site investigation to structural thickness design, tailored to local ground conditions and traffic loads.
Subgrade Investigation & CBR Testing
Test pits, DCP profiling, and laboratory CBR soaked/unsoaked tests to classify subgrade strength and moisture sensitivity across Geelong's varied geology.
Concrete Slab Thickness Design
Iterative fatigue analysis using Austroads AGPT04A-17, selecting slab thickness, joint spacing, and concrete flexural strength for T2 to T8 traffic classes.
Drainage & Subbase Specification
Design of granular subbase, edge drains, and geotextile separation layers to control moisture and prevent pumping in Geelong's high-water-table areas.
Frequently asked questions
What is the difference between rigid and flexible pavement design?
Rigid pavements use a Portland cement concrete slab that distributes loads through flexural strength, while flexible pavements use layered asphalt over granular bases. Rigid designs are preferred for heavy traffic and where subgrade is weak but uniform, like Geelong's industrial zones. The key parameter shifts from CBR (flexible) to k-value (rigid).
How much does rigid pavement design cost in Geelong?
A full rigid pavement design including site investigation, laboratory testing, and structural thickness report typically ranges between AU$2.840 and AU$9.310, depending on pavement area, number of test pits, and traffic class. Additional costs apply for plate load tests or groundwater monitoring.
What subgrade conditions in Geelong require special attention for rigid pavements?
Soft alluvial clays and silts in low-lying suburbs like Newcomb, Whittington, and along the Barwon River floodplain have low k-values (<30 MPa/m) and high moisture sensitivity. These conditions demand a thicker slab, a drainage layer, and often a subbase of crushed rock to avoid differential settlement and pumping.