By Dr Hadi Nourizadeh, Research Fellow, Centre for Future Materials, University of Southern Queensland

The relentless demand for materials has led to an exponential rise in waste generation, posing severe environmental concerns, particularly in relation to greenhouse gas emissions and the overflowing of landfills. 

Australia alone produces nearly 76 million tonnes of waste each year, with 25 million tonnes originating from construction activities and 1.6 million tonnes from waste glass. Surprisingly, less than 10 per cent of this glass is recycled for manufacturing purposes, primarily due to impurities and the mixed colours of glass waste. But what if these discarded beer bottles and glass materials could be given a second life, playing a pivotal role in transforming construction materials? 

A promising solution lies in repurposing waste materials to formulate new products, significantly reducing the strain on landfills and the environment. The construction industry, a major consumer of materials, is at the forefront of this initiative.

The growing demand for sustainable materials

Over the past few decades, industrialisation and infrastructural growth have led to a significant rise in the production of construction materials. Cement, particularly ordinary Portland cement (OPC), has been a key player in this expansion; however, the environmental impact of OPC is alarming. Currently, global production of OPC is growing by nine per cent annually, contributing to approximately 1.5 billion tonnes of greenhouse gases each year. This accounts for 6–10 per cent of total global emissions. Projections suggest that by 2050, cement production could surpass 4000 million tonnes annually, intensifying concerns over its carbon footprint. 

In addition to environmental concerns, the cement industry faces challenges like rising energy costs, regulatory pressures to reduce carbon dioxide emissions and the scarcity of high-quality raw materials. While efforts are being made to improve cement technologies, meeting ambitious emission reduction targets will require technological advancements and new strategies. 

One such strategy is to reduce the reliance on traditional cement by integrating industrial waste and low-carbon alternatives, such as blended cements. Replacing virgin raw materials with recycled or reclaimed alternatives is critical to this goal.

The role of grout in mining and construction

Grout is an essential material in geotechnical and mining applications, enhancing ground stability, load‑bearing capacity and overall durability. In mining, grout is often used in rock-bolting and cable-bolting systems, where it transfers stress between the rock mass and the bolt, ensuring the integrity of underground excavations. Typically, cement is the primary binder in cementitious grouts, with OPC being the most commonly used due to its hydraulic properties; however, the cement production process is energy‑intensive and contributes approximately seven per cent of global greenhouse gas emissions. 

With growing environmental concerns, the shift toward greener technologies is more crucial than ever. One approach is to partially replace traditional cement in grouts with supplementary waste materials, such as tailings, fly-ash, blast furnace slag and waste glass. Not only does this reduce the environmental impact by lowering emissions and diverting waste from landfills, but it also mitigates the depletion of natural resources.

A sustainable solution: waste‑based grouts

Our research introduces eco-friendly grout formulations that incorporate both pozzolanic and non-pozzolanic waste materials, offering a more sustainable approach to mining and construction. Led by Associate Professor Ali Mirzaghorbanali and myself, this project is conducted under the Sustainable Industry Manufacturing Planning for Long-term Ecosystems (SIMPLE) Hub. 

The project explores innovative grout products by replacing a portion of conventional clinker with recycled waste materials like glass, construction debris, recycled tyres and composite materials. 

Supported by the Australian Government and industry partners, the SIMPLE Hub, led by the University of Southern Queensland and its Centre for Future Materials, aims to create an ecosystem that bridges industry and academia, advancing sustainable practices for long-term impact. The aim is to foster the development of cleaner, more efficient, and scalable industrial solutions that contribute to a circular economy. 

Through this project, in partnership with Jennmar Australia, more than 500 grout specimens have been cast, tested and analysed to evaluate their mechanical, microstructural, chemical, and rheological properties. The results have been promising, showing that grouts containing waste materials, such as waste glass, construction and demolition waste, and tyre rubber powder, can meet industry requirements for mechanical and rheological performance. This research paves the way for the broader application of sustainable cementitious grouts in mining and construction.

A greener future for the industry

The environmental and ecological benefits of integrating waste materials into cementitious grouts are substantial. These include diverting waste from landfills, reducing the consumption of non‑renewable natural resources, lowering the energy demand of cement production and mitigating greenhouse gas emissions. The use of alternative supplementary materials not only enhances grout performance, but also promotes the development of climate‑smart infrastructure. 

As the industry continues to search for ways to mitigate its environmental impact, the adoption of waste-based grouts offers a practical, scalable solution. The SIMPLE Hub’s research and development efforts will contribute to shaping a more sustainable future for mining and construction, demonstrating that innovative materials can go hand in hand with environmental responsibility. 

By reimagining waste as a resource, we can unlock new opportunities for sustainability, creating a construction industry that is not only more efficient, but also more attuned to the needs of the planet.