How Recycled Glass Blocks are Reinventing Construction
Sustainability in construction is no longer a fringe idea. It’s a necessity. Amid the growing urgency to decarbonise the built environment, one innovation is turning heads: compressed earth blocks (CEBs) reinforced with recycled glass. And not just as filler – scientists have discovered a sweet spot in the mix that transforms waste into strength.
A ground-breaking study, published in Discover Civil Engineering, has revealed how powdered recycled glass, when used in tandem with lime, can significantly improve the structural properties of compressed earth blocks. This research, spearheaded by the University of Portsmouth alongside institutions from Ghana, Nigeria, and the UK, could shift how we think about building materials in the race toward net-zero.
A Powerful Stabiliser
Traditionally, CEBs are stabilised with cement, a material notorious for its high carbon footprint. But now, researchers have demonstrated that recycled waste glass particles (RWGP) can be just as effective – and in some cases, even better – when used in the right proportions with lime.
The study tested blocks incorporating RWGP at ratios from 0 to 25 percent, combined with lime and varying amounts of cement. The team wanted to discover how well the blocks performed in terms of compressive strength, tensile strength, and water absorption.
Dr Muhammad Ali, Associate Professor in Materials and Environmental Innovation at the University of Portsmouth, explained the rationale: “There is an increased demand for the use of recycled industrial waste as sustainable building and construction materials so we wanted to assess the properties of compressed earth blocks using recycled glass particles.”
Their testing revealed that the optimal combination was 10 percent lime and 10 percent RWGP. This mix delivered the best mechanical results across the board, outperforming even blocks with higher glass content.
The Numbers Tell the Story
At 28 days of curing, blocks made with the 10/10 mix recorded a compressive strength of 5.77 MPa, nearly doubling the 3.03 MPa achieved by unstabilised samples. Similarly, the tensile strength hit 0.52 MPa, a 30 percent improvement over the 0.40 MPa baseline.
Perhaps most impressively, electron microscopy showed no cracks in the 10/10 blocks, while mixes with 25 percent glass displayed micro-cracks. This suggests that overloading the mix with glass can compromise integrity, while the right balance boosts durability without brittleness.
Why This Matters for Construction
For industry professionals, this research holds significant promise. Not only does it introduce a practical application for glass waste – a persistent issue for local authorities worldwide – but it also reduces reliance on cement, whose production contributes around 8 percent of global CO2 emissions.
In regions where soil-rich land is readily available, and glass waste is abundant, this solution could offer a cost-effective and low-carbon alternative to traditional bricks and blocks. Better still, compressed earth blocks don’t require energy-intensive firing, unlike kiln-baked bricks.
The green benefits of adopting these new formulations are:
- Reduced cement usage
- Lower embodied carbon
- Diversion of glass from landfills
- Improved insulation properties (pending further study)
It could be a game-changer, particularly for low-rise buildings in developing regions, where affordability and access to conventional materials remain key challenges.
The Global Research Collaboration
This wasn’t a solo effort. The study was the result of international collaboration, highlighting the power of global knowledge exchange in tackling sustainability challenges.
Partner institutions included:
- University of Portsmouth (UK)
- Akenten Appiah-Menka University (Ghana)
- London South Bank University (UK)
- Federal University of Technology (Nigeria)
- CSIR-Forestry Research Institute (Ghana)
Such collaborative efforts are increasingly vital in the era of climate change, where context-specific solutions are needed for diverse geographical and socio-economic settings.
What Comes Next?
While the results are promising, the researchers acknowledge that this is only the beginning. Further investigations are needed to explore the thermal and long-term durability properties of glass-lime CEBs. Key areas for future exploration include:
- How these blocks perform in extreme weather conditions
- Thermal insulation values and energy-saving potential
- Resistance to erosion, humidity, and seismic activity
- Full lifecycle assessment and cost-benefit analysis
Such data will be essential in convincing regulators, architects, and contractors to make the switch from traditional materials to earth-based alternatives.
Scaling the Solution
One hurdle remains: scaling up production. While laboratory testing shows great promise, moving from bench-scale experiments to commercial production lines requires new machinery, policy support, and market incentives.
However, the potential payoff is enormous. With the right investment, recycled glass stabilised CEBs could become part of the broader push to develop locally produced, eco-friendly construction solutions that also support circular economy goals.
Governments and policymakers also have a role to play. Through revised building codes, tax incentives, and R&D funding, they can accelerate the adoption of alternative materials that align with net-zero targets.
A Brighter, Cleaner Tomorrow
Turning glass bottles into homes might have sounded far-fetched a few decades ago. Today, it’s a real possibility with tangible benefits. As global cities continue to expand and the climate crisis deepens, innovations like this offer a glimpse of how construction can pivot towards a more responsible future.
By merging science with sustainability, researchers are laying the groundwork for a greener built environment – one recycled block at a time.
