The slipform paver lays concrete across Sunshine Coast's expanding road network, placing slabs that must resist fatigue from repeated axle loads. Our rigid pavement design evaluates subgrade modulus, concrete flexural strength, and joint spacing to prevent cracking under the region's humid subtropical climate. Before specifying slab thickness, we run [MASW surveys](/masw-vs30/) to map soil stiffness profiles across project sites. This data feeds into mechanistic-empirical models that predict pavement life under projected traffic volumes. We also assess drainage conditions because water trapped beneath rigid pavements accelerates pumping and faulting. Every design references Austroads Guide to Pavement Technology Part 2 for structural design procedures.
Subgrade k-values on Sunshine Coast can drop below 30 MPa/m in wet alluvial zones, demanding thicker slabs and load transfer systems.
Scope of work
A common oversight on Sunshine Coast projects is assuming the sandy loam topsoil extends uniformly. In reality, the subgrade varies from soft alluvial clays along the Maroochy River to stiff residual soils near the Glass House Mountains. Our rigid pavement design process includes these specific steps:
Plate load tests (Austroads T109) to determine modulus of subgrade reaction (k-value)
Concrete mix design targeting 4.5 MPa flexural strength at 28 days
Joint layout optimisation to control curling and warping stresses
We also check for expansive soils using Atterberg limits — a critical factor often missed on coastal developments. The final design delivers a 30-year service life with maintenance intervals aligned to local council asset management plans.
Technical reference image — Sunshine Coast
Area-specific notes
Some contractors on Sunshine Coast skip the subgrade investigation and copy slab designs from Brisbane projects. That mistake costs dearly when the pavement sits on compressible estuarine clays near the coast. Without proper rigid pavement design, slabs crack from differential settlement, corner breaks appear within two years, and pumping stains the surface. The repair bill often exceeds the original paving cost. We have seen pavements fail in under five years because nobody checked the water table depth or the soil's swelling potential. A thorough geotechnical assessment upfront eliminates these risks and keeps the project on schedule.
Driveways, pathways, and low-traffic streets. Plate load tests confirm k-values, and we specify dowel-free joints for cost savings. Design reports include construction tolerances and curing requirements.
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Industrial & Heavy-Duty Pavements
Warehouses, loading docks, and truck terminals. We calculate slab thickness for axle loads up to 50 tonnes, using steel fibre-reinforced concrete where joint maintenance is a concern. Fatigue analysis follows the Miner's rule approach.
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Airfield Pavement Design
Aprons and taxiways at Sunshine Coast Airport. We evaluate subgrade stabilisation needs and design slabs that withstand aircraft gear loads. Joint sealant selection considers fuel spill resistance.
Standards used
Austroads Guide to Pavement Technology Part 2: Structural Design (AGPT02), AS 3600 Concrete Structures, AS 1726 Geotechnical Site Investigations, Austroads T109 Plate Load Test for Subgrade
Frequently asked questions
What factors influence rigid pavement thickness on Sunshine Coast?
The main factors are subgrade k-value, concrete flexural strength, traffic loading (axle repetitions), and environmental conditions like temperature gradients. On Sunshine Coast, the coastal climate causes high moisture variations, so we also consider the subgrade's drainage characteristics.
How much does rigid pavement design cost in this region?
Design fees typically range between AU$2,750 and AU$10,570 depending on project size, number of test pits, and traffic analysis complexity. A standard residential driveway design with one plate load test is on the lower end, while a multi-lane industrial pavement with full laboratory testing sits at the higher end.
What is the difference between rigid and flexible pavement design?
Rigid pavements use a concrete slab that distributes loads through beam action, relying on the slab's flexural strength. Flexible pavements use asphalt layers that transfer load through aggregate interlock. Rigid pavements last longer in wet environments but require proper joint design and subgrade support to avoid cracking.
Do I need a geotechnical investigation before rigid pavement design?
Yes. Without knowing the subgrade modulus and soil classification, you risk overdesigning or underdesigning the slab. We recommend at least two test pits per site to assess soil variability, plus a plate load test to measure the k-value. This data directly feeds into the thickness calculation.
Can rigid pavement be installed on reactive clay soils?
It can, but only after subgrade treatment. Expansive clays present on Sunshine Coast require moisture barriers, subgrade stabilisation with lime or cement, and thicker slabs to resist heave. Our design includes a risk assessment based on soil shrinkage index and depth of active zone.
