The team mobilizes a combination of pneumatic rollers, pugmill mixers, and grader-spreaders to treat the sandy subgrade typical of Hervey Bay. For projects near the Fraser Island ferry terminal, the high water table demands a staged approach: first a CBR test to measure soak strength, then lime application at 3–5% by dry weight to reduce plasticity. In the southern corridor toward Maryborough, the clay content increases, so cement stabilization at 4–6% is more common. Equipment calibration follows AS 1289.1.4.1, and each batch is verified with field density cones.
Lime treatment at 3–5% by dry weight reduces plasticity index by 15–20 points in Hervey Bay's coastal clays, meeting subgrade CBR targets of 8–15%.
Service characteristics in Hervey Bay
Critical ground factors in Hervey Bay
Hervey Bay sits on Quaternary alluvial and coastal sands, with groundwater at depths of 1–3 m near the Esplanade. A 2021 council report identified 14 road sections where pavement failure occurred due to inadequate subgrade stabilization — mostly in the Kawungan and Scarness areas. The risk is compounded by expansive clays in the western suburbs, which can heave up to 30 mm during wet seasons. Soil stabilization for roads must address both strength and swell potential; untreated subgrades here fail within 3–5 years under standard traffic loads.
Our services
Two complementary stabilization methods are offered for Hervey Bay road projects:
Lime Stabilization for Clay Subgrades
Hydrated lime is spread and mixed to depths of 300 mm using a pulverizer-mixer. The reaction reduces plasticity index by 15–20 points and increases CBR from 3–5% to 12–20%. Suitable for residential streets in Torquay and Point Vernon where clay content exceeds 30%.
Cement Stabilization for Sandy Subgrades
General purpose cement at 4–6% by weight is blended into sandy soils common around Dundowran and Nikenbah. Achieves unconfined compressive strengths of 1.5–2.5 MPa at 7 days. Ideal for collector roads and bus routes where traffic loading is moderate.
Frequently asked questions
What is the typical cost range for road soil stabilization in Hervey Bay?
For a standard 300 mm treatment depth, costs range from AU$1,420 to AU$5,220 per 100 m² depending on additive type (lime vs cement), site access, and volume. This includes laboratory mix design, field application, and compaction testing.
How long does stabilized subgrade take to cure before paving?
Cement-treated layers require 7 days of moist curing before asphalt overlay, while lime-treated soils need 14–21 days to complete the pozzolanic reaction. Temperature and rainfall in Hervey Bay influence the exact schedule — we perform daily CBR checks to confirm readiness.
What tests are performed after stabilization to verify quality?
Field density is checked using the sand cone method per AS 1289.5.3.1. Unconfined compressive strength samples are taken at 7 and 28 days. CBR tests on soaked specimens confirm design strength. An additional swell test is run on clay subgrades to limit expansion below 2%.
Does Hervey Bay have specific council requirements for road stabilization?
Yes, the Fraser Coast Regional Council requires a geotechnical report for any subdivision road construction. The report must include Atterberg limits, compaction curves, and CBR values for the stabilized layer. Our procedures align with council's standard specification for pavement subgrades.