Emerging Materials – Olivine the Natural, Abundant, Carbon Sequestering Concrete.
Dubbed ‘the world’s first carbon-negative concrete in the world’, olivine concrete offers all the qualities of traditional concrete at less environmental impact and no compromise on strength or durability.
The olivine mineral is a magnesium iron silicate that is the primary component of the earth’s upper mantle (60-80%). It is commonly found on the earth’s subsurface but weathers in surface conditions. This weathering process, known as mineral carbonation, is what makes olivine so useful. Olivine minerals react with atmospheric carbon dioxide sequestering CO2 and storing it in solid form. It has been proposed for a number of climate mitigation applications as a cheap way to sequester carbon, including the development of low-carbon concrete.
The Practicalities of Olivine
The olivine weathering process can take decades to occur naturally. However, enhanced weathering techniques can accelerate the reaction and carbon absorption. Rapid carbonation can be achieved by processing ground olivine minerals using a combination of pressure, high temperatures and carbon dioxide in an autoclave. The products of this process are mainly magnesium carbonate and silica. Magnesium carbonate has several material uses, from special types of cement to paper and polymers, whilst silica can be used as an SCM (supplementary cementitious material). Most importantly, these products contain stored carbon, so when traditional Portland cement is partially substituted with silica from processed olivine, it renders the concrete carbon neutral or even carbon negative.
The carbon reduction prospects of this concrete are outstanding. According to Climate KIC, over 850,000 tonnes of carbon dioxide could be captured through small-scale applications in Rotterdam civil construction projects alone.
The Benefits of Olivine and the Solution to Concrete Emissions
Concrete is the most consumed material in the world, 2nd only to water, but it is also one of the most harmful, with 8% of global CO2 emissions attributed to its production. The scale of global concrete production makes finding an alternative both necessary and challenging. A practical and inexpensive solution is in high demand to incentivise the use of sustainable concrete alternatives. Olivine-based concrete seems to offer a solution on all fronts:
- The production process not only consumes large amounts of CO2 but is less carbon-intensive than that of Portland cement.
- Olivine concrete has impressive circularity potential; it could enable cement production to reuse waste CO2 from other industries or even their own processes.
- Olivine-based SCM can easily be incorporated into recycled concrete production, further reducing the material’s carbon footprint.
- The concrete would maintain the popular properties of conventional concrete, such as its strength and durability.
- Due to its similarities to conventional concrete, no new construction knowledge or skills are required for its application.
- The mineral itself is naturally occurring, inexpensive and abundant.
What's Next for this Miracle Material
The future of olivine materials looks promising and has already generated interest. The Dutch start-up, Green Minerals partnered with Heidelberg Materials (one of the largest building material companies in the world) to launch a 3-year research project into olivine alternatives and has developed multiple olivine-based materials. Aireal claims Green Minerals’ concrete can capture up to 133 kg of CO2 per tonne. A British company, Seratech, won the 2022 Obel Award for their olivine carbon-neutral concrete and is replacing traditional cement mix with up to 40% of their SCM.
Olivine concrete is yet to see widespread applications as its development is so recent. Further research is being done on refining the process to maximise carbon saturation with as little energy expenditure as possible. There is little doubt that olivine concrete and other alternatives will greatly impact the construction industry in the future. These mineral alternatives could revolutionise cement production, which is desperately needed for an industry that holds the highest carbon intensity per unit of revenue.
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