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Extra-strong concrete — with coffee

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29 May, 2024

This post was originally published on Sustainability Matters

RMIT University has come up with a novel use for spent coffee grounds — as a valuable component in concrete.

The university is currently collaborating with Macedon Ranges Shire Council on a coffee concrete footpath trial in Gisborne.

RMIT has several other projects planned across Victoria in which coffee grounds will be turned into biochar and transformed into a resource for the construction industry. The RMIT team will partner with Australian-owned BildGroup — a civil infrastructure, asphalt paving and road profiling company — to deliver these circular-economy projects.

Australia generates 75 million kilograms of ground coffee waste every year. Most of this waste currently goes to landfill, but it has the potential to replace up to 655m kg of sand in concrete because spent coffee is a denser material. Globally, 10bn kg of spent coffee is generated annually, which could replace up to 90bn kg of sand in concrete.

The team’s coffee biochar (left) next to spent coffee. Credit: Carelle Mulawa-Richards, RMIT University.

While organic waste like coffee grounds cannot be added directly to concrete because it would decompose over time and weaken the building material, the RMIT team has developed a technique to make a suitable coffee biochar via a low-energy process without oxygen at 350°C. The resulting mixture makes the concrete 30% stronger, the researchers said.

The team is using a similar technique to turn other organic waste, including wood chips, into biochar that can also be used to make stronger concrete. Both types of biochar are being tested in the Macedon Ranges footpath trial.

Council officers and the RMIT research team were present for the pour of the coffee concrete for the footpath trial in Gisborne. Credit: Carelle Mulawa-Richards, RMIT University.

“It’s very exciting to see this world-first trial of our coffee and wood-based biochar in these footpaths collaboration with Macedon Ranges Shire Council,” said Dr Rajeev Roychand, from RMIT’s School of Engineering.

“Sand is getting scarce over time, and this waste can replace up to 15% of the sand in concrete.”

Shane Walden, Council’s Director of Assets and Operations, said it was important for the council to be involved in projects such as this and to be working closely with universities like RMIT.

“This not only helps improve the knowledge level of our contractors and our staff, but it also has lots of other benefits and benefits that are important to our community,” he said.

“This includes helping the environment, acting sustainably and, most importantly, reducing waste to landfill and having a circular economy.”

Walden said that despite the fact that the new concrete contains coffee grounds or mulch, residents aren’t really going to see or smell any difference.

Turning coffee concrete into a commercial reality

If the trial concrete footpaths in Gisborne perform well, the RMIT team is aiming for the commercial rollout of its innovation.

“We are currently working in the supply chain sector so that we can make this research into a mainstream product for commercial applications, and we’re not only looking into coffee ­— we’re expanding this into all forms of different organic waste,” Roychand said.

“Every biochar produced from a different organic material comes with varying composition, in addition to the difference in carbon content, particle size and absorbency, that can boost the performance of concrete in a range of ways.”

If this RMIT innovation can be integrated into the supply chain, it might bring cost savings for construction companies and concreters by reducing the amount of cement needed.

“Since we are achieving a 30% increase in strength for the coffee concrete, this could reduce the required cement content by as much as 10%, based on our previous experience,” Roychand said.

The trial with Macedon Ranges Shire Council did not reduce the amount of cement normally used to make concrete for footpath projects, but the RMIT team plans to experiment with using less cement in future.

Transforming spent coffee grounds into a valuable resource for the enhancement of concrete strength’ has been published in the Journal of Cleaner Production.

Top image caption: The first pour of the coffee concrete for the footpath trial in Gisborne. Credit: Carelle Mulawa-Richards, RMIT University.

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Energy Efficiency as an Imperative Climate Strategy

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With mandatory climate statement disclosure rolling out in Australia, businesses need to start reporting on their emissions and sustainability plans for the future. As companies begin assessing the relevant risks and opportunities related to various climate scenarios, energy efficiency presents itself as an immediate climate-strategy with long-term benefits.

Commencing 1 January 2025, businesses that meet two of the three conditions — more than 500 employees, gross assets above $1 billion or $500 million or more in consolidated gross revenue — are required to lodge a climate statement, which discloses their climate-related plans, financial risks and obligations. As part of the gradual roll-out, by 1 July 2027, businesses that meet two of these conditions — more than 100 employees, gross assets above $25 million or exceeding $50 million in consolidated gross revenue — will also be required to report.

This climate statement will need to include the company’s sustainability governance, climate risks and opportunities, including those physical and transition related. They will also need to disclose their Scope 1 and 2 emissions, strategy to decarbonise, and conduct scenario analysis on the short, medium and long term impacts on the business. By the second year of reporting, businesses will also be expected to report on Scope 3 emissions.

Scenario analysis will be based on various assumptions of the state of the climate, one of which includes a possible future where global temperature has increased 2.5°C or more. They will be required to share their climate strategy and steps they are taking long-term in preparation for this scenario.

Common themes within climate strategies will include switching to renewable energy sources, electrifying fleet vehicles, purchasing carbon credits, and carbon capture and storage. Many of these methods look at reducing emissions through the energy source, or targeting the carbon aspect directly; however, climate strategies can also include reducing the amount of energy used. By investing in more energy efficient equipment, sites can maintain production whilst using less energy and producing less emissions.

When increasing energy efficiency and reducing energy consumption first, businesses will see short-term impacts; however, in the long term, they are also improving their foundation for an energy transition. Assuming no other changes, higher energy efficiency can lead to decreased energy demand, allowing for reduced system requirements when specifying and planning for self-generation or energy costs.

To understand what opportunities are available for upgrading to more energy efficient equipment, businesses can start with an energy audit to understand how energy is being consumed across site. Energy audits, like the ABB Energy Appraisal, can provide a roadmap for where and how equipment can be upgraded for the best energy saving potential. An energy audit identifies areas that can be immediately improved with existing equipment on the market, so there is no need to wait for the commercialization or development of more sustainable technology. Going beyond just changing all lights to LEDs, efficiency recommendations may include areas where variable speed drives can be added to control motor speed or upgrading from an IE3 motor to an IE5 ultra-premium efficiency or IE6 hyper-premium efficiency motor to reduce energy losses by 40% or more. This area can often be overlooked on sites as the Minimum Energy Performance Standard (MEPS) in Australia for motors is just IE2.

Mostly used in pumps, compressors, conveyors and fans, motors may seem like a minor part of a site; however, with 45% of the world’s electricity converted into motion by industrial electric motors, there are many opportunities for energy savings. In fact, a recent survey commissioned by ABB IEC Low voltage motors, showed that 92% of surveyed businesses in Australia recognize the important role of electric motors in achieving sustainability targets. In this same survey, participants ranked a reduction in operating cost as a more important driver for investing in energy efficiency than lowering their organization’s emissions. This is because upgrading to newer, more efficient equipment provides benefits beyond just emission reduction. For example, ABB’s Synchronous Reluctance (SynRM) Motors, available in IE5 ultra-premium efficiency or IE6 hyper-premium efficiency, use no rare earth metals or magnets. Running quieter and with bearing temperatures reduced by up to 15°C and winding temperatures by up to 30°, SynRM motors have longer maintenance periods, superior reliability, and contribute to a better operational environment.

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By requiring companies to disclose their climate information, these new legal requirements are opening the door and facilitating more internal discussions on environmental impact and emission reduction. Whilst mandatory climate reporting is only required of large business entities this year, the progressive roll-out and Scope 3 emission reporting requirements mean that businesses of all sizes in Australia will be impacted by these new requirements. As businesses become more conscious of how sustainability should be integrated into their operations and finances, there is no better time to start investing in energy efficient solutions.

For more information, click here.

Image credit: iStock.com/denizunlusu

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