EIC Activities is collaborating with Western Sydney University in conjunction with the Australian Research Council and industry partners to develop an alkaline-activated treatment of expansive soils originating from Bringelly shale.
The research is looking to develop a low-carbon alternative to the use of lime or cement, which should provide a significant increase in strength and stiffness, as well as a reduction in shrink-swell behaviour.
About expansive soils
Expansive soils exhibit shrink and swell behaviours when moisture conditions change in the soil. Covering one-fifth of Australia’s surface area, expansive soils can damage infrastructure in a number of ways, including:
- cracks may develop on pavements
- retaining walls may bulge and tilt
- cracking may occur in brick walls of buildings
- foundations of structures may move or be damaged.
Current soil treatment techniques for addressing the problems caused by expansive soils include:
- replacement of expansive materials (as the name suggests - removing the soil and replacing it with alternative materials)
- special foundation techniques (e.g. piles, raft footings, ground anchors)
- changing the nature of expansive soils (e.g. prewetting, compaction, moisture barriers, preloading)
- chemical treatment (e.g. cement, lime, fly ash).
Alkali-activated (geopolymer) stabilisation of expansive soils
The research is seeking a method to stabilise expansive soils using alkali-activated binders. The team has identified strengths and challenges of the application:
Strengths
- Strong and durable treated soils
- Low-carbon footprint compared to cement and lime
- Rapid strength gains with alkali-activated binders, which is beneficial for construction timelines
- Resistant to sulphate attack, which is an issue with lime treatment, especially in sulphate-rich soil
Challenges
- Industrial waste precursors (e.g. fly ash, slags) used for alkali-activation not available in all locations
- Other precursors (e.g. metakaolin) produced by high-temperature calcination
- Complex application requiring careful control and mix design processes
- A higher cost compared to lime.
We look forward to seeing the outcome of the research into this new soil stabilisation method for expansive soils and will provide a further update when the research results are available.
About EIC Activities’ involvement with university research
EIC Activities partners with leading universities, supporting research to improve sustainable infrastructure delivery and outcomes. We are currently partnering with University of Technology Sydney (NiCE Hub), Western Sydney University (expansive soil treatment) and Monash University (SPARC Hub).