Is it possible to grow cement?  

 Innovation thrives when people pause to observe, question and reimagine the world around them, turning challenges into opportunities for progress. Nature in particular serves as a rich source of inspiration for innovative solutions. 

 One of the current challenges is the production of concrete, which is accountable for a significant portion of the global CO emissions. In addition, the world’s building stock is expected to double by 2060 – the equivalent of building an entire New York City every month for the next 36 years, which means an incredible increase in the demand for cement and concrete. 

 Faced with this daunting situation, is there anything humans can do? In this article, Loren Burnett, chief executive officer of Prometheus Materials, describes how it has developed a material that mimics nature’s processes to recreate concrete as it is known. 

Cultivating raw material 

 The journey began with an initiative to find sustainable and readily available raw materials for construction in resource-deprived environments. 

 Over a period of five years, four professors from the University of Boulder in Colorado have developed a new process that uses microalgae as a building material. Instead of creating a new raw material, they cultivated one.  

 Those professors, together with Loren Burnett, co-founded Prometheus Materials in 2021, and continue to play active advisory roles in the company. 

 Inspiration from nature 

 The process harnesses the remarkable capabilities of naturally occurring microalgae. Inside water-filled bioreactors, these microalgae are stimulated to produce chlorophyll, aided by strategically placed light-emitting diodes.  

 Infused with nutrients and natural ingredients, the water facilitates the formation of calcium carbonate through a process known as biomineralisation. In essence, this is similar to the natural creation of shells and coral reefs, but they were able to harness and accelerate it to a level where it becomes the raw material for a highly efficient zero-carbon bio-cement production. 

“When mixed with aggregate, the bio-cement forms a zero-carbon bio-concrete with mechanical, physical and thermal properties that are comparable or superior to Portland cement-based concrete. 

 “Our process both avoids the carbon-intensive operations involved in manufacturing and transporting traditional cement and sequesters embodied carbon from the microalgae and biomineralisation. Another essential feature of our solution is that virtually all the water used in production is returned to the earth,” says Burnett. 

 Performance 

 The aggregate is locally sourced, with an emphasis on incorporating recycled materials wherever possible. Prometheus concrete demonstrates impressive performance in several parameters compared to traditional concrete: 

  • It is 15% to 20% lighter. 
  • The compressive strength rivals that of traditional concrete. 
  • The flexural strength is three to four times greater. 
  • The bond strength has a modulus of rupture (MOR) of 660-990 PSI, compared to 200-325 PSI for traditional concrete. 

 The acoustic properties outperform traditional concrete with a noise-ratio coefficient (NRC) of 0,60 compared to 0,05, and additional sound transmission testing is underway. The material also excels in thermal insulation, reducing thermal transmission by 90% compared to traditional concrete, thus reducing operating carbon, as well as eliminating embodied carbon. 

 Manufacturing and production 

 Traditional architecture firm, Skidmore, Owings & Merrill (SOM), has unveiled Bio-Block™ Spiral, in collaboration with Prometheus Materials. SOM designed a spiral installation of bio-blocks with building blocks rotated to create openings and pleated ends to enhance the structure. The installation highlights the simplicity of block and mortar construction while demonstrating the versatility of the bio-block form.  

 Sustainability goals 

 Prometheus’ emphasis is on combatting climate change while meeting the growing demands of the construction sector. Burnett says: “There are currently ~53 gigatons of CO emitted globally on an annual basis – and this number is increasing, not decreasing. Our overall goal at Prometheus Materials is, in time, to reduce the CO emissions by a gigaton or more per year.” 

New technology process uses microalgae as a building material. Instead of creating a new raw material, they cultivated one. 

 Full acknowledgement and thanks go to www.archdaily.com for the information in this editorial. 

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