Subgrade Recycling
& Fill Drying

Hiway Group are industry leaders in subgrade recycling and fill drying solutions, providing faster, lower cost recycling with subgrade modification.

With extensive experience with all New Zealand, Australian and Pacific soil types, our team can offer expert advice and laboratory testing to confirm the natural versus post-treatment strength of subgrade material.


Construction of new and recycling, reuse of existing pavements

Moisture conditioning of earthworks for residential subdivisions

Fill drying for extension of earthworks construction seasons

Recycling and reuse of subgrades for civil and infrastructure projects

Recycling and reuse of subgrades for industrial and commercial developments


Significantly improved in-situ subgrade stability

Subgrade strength gains of up to 20 times

Cost savings due to reduced requirement for imported aggregates, fewer transport costs and faster construction time

Reduces risk of costly subgrade pavement failures

A robust, durable platform for aggregate construction

Substantially reduces moisture susceptibility

Creates a more uniform pavement layer

Recycling of the subgrade forms a soil particle and moisture barrier that protects overlying aggregate layers from upward migration of plastic fines

Dries large volumes of water-logged soil instantly

Can be carried out in poor weather conditions

Reduces down-time by enabling earthworks to continue immediately after wet weather

May enable reduced pavement thickness, providing significant cost savings

Subgrade Recycling

Hiway Group has been an industry leader in subgrade improvement, recycling and reuse solutions for over thirty years. Our track record covers a wide range of applications, from local authority roads to site works for land developers and major infrastructure projects for Government.

Our subgrade recycling, reuse and fill drying services enable the construction of pavements, buildings and infrastructure to be carried out faster, more environmentally sustainable and more cost effectively, even in adverse conditions.

Fill Drying

Hiway Group pioneered the use of fill drying in New Zealand and we are actively developing its use with road authorities and land developers across Australasia.

Fill drying involves the chemical drying of existing ground, converting unusable soils into a usable and controlled engineered fill. As a highly effective way to combat wet soil, it enables earthworks to continue in adverse conditions, using existing on-site materials, and allows water-logged soils to be used instantly.

Fill drying also increases the strength of the subgrade substantially, reducing the requirements for cut to waste, enabling greater reuse of the existing on-site materials and reducing the need for imported aggregate. The process is particularly well suited to sites where tight construction programmes, winter earthworks programmes or limited drying areas are an issue.

Fill drying increases the strength of the subgrade substantially, reducing the requirements for cut to waste.


As Australasia’s largest provider of specialist transport infrastructure stabilisation, recycling and reuse technologies, our expertise and commitment to innovation has seen us develop solutions that optimise material properties to make them ideal for the specific conditions we’re working in. We are equipped to tackle the most demanding of sites, achieving almost instantaneous results and maintaining high production outputs.

Cost & Carbon Calculator

Use Hiway Group’s carbon calculator to determine your potential carbon emission offsetting and cost savings.

Calculate Your Savings

Engineering & Design

Hiway Group is the only specialist stabilisation, recycling and reuse contractor in Australasia to provide extensive in-house design services.

From concept design to delivery, our team provides a ‘one-stop-shop’ for the design of recycled pavements, foam bitumen recycling, stabilising, pavement rehabilitation, heavy duty and overlay pavements.

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