Bacteria to the rescue

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Headline: Hydrogel encapsulated bacteria make way for ‘self-repairing’ concrete, study says.

Summary: Researchers from Drexel University’s College of Engineering are experimenting with bacterial fiber reinforcements through a process known as microbial-induced calcium carbonate precipitation (MICCP). The process self-repairs concrete, extending the lifetime of the ubiquitous building material that’s responsible for 8% of global carbon emissions. The initial results are promising.

So what: Concrete is among the most-utilized material in construction due to its durability, cost-effectiveness, and ubiquity. It’s also one of the oldest. The Roman Empire tapped a unique blend of concrete that has endured the test of time. But concrete is not perfect. For all its benefits, concrete’s carbon footprint, high cost of repairs, and inflexibility once installed have created a series of challenges. If today’s concrete buildings could last as long as ancient Roman buildings with less ongoing maintenance, could that potentially redeem some of its shortcomings? Drexel researchers think it could.

Under the surface:  Much like our relatively fresh understanding of Roman concrete, researchers today are encouraged by a bacterial-induced chemical reaction embedded into the mortar. These fibers, known as lysinibacillus sphaericus, mimic our skin’s regenerative tissue to create a self-healing system where the bacteria germinate when water enters a crack in the concrete. The bacteria are in microcapsules that are added to the concrete mix. When water enters a crack in the concrete, the microcapsules break open, releasing the bacteria. The bacteria germinate to produce calcium carbonate, which fills the crack and prevents further damage. This is similar to the chemical reaction found in the Roman volcanic ash, lime, and water mortar blend when mixed with saltwater to produce binding Tobermorite crystals.

• Global cement production emits 2.8 trillion tons of CO₂ per year, accounting for 7-8% of global CO₂ emissions.

• Concrete structures can degrade in as few as 50 years.

• Several startups are looking to address the problem in different ways with carbon-negative cement production.

Net, net: While commercial timelines remain uncertain, significant progress is underway to tackle concrete's limitations. Self-healing concrete holds promise by minimizing costly repairs and maintenance, saving time and money. Additionally, it has the potential to enhance environmental sustainability by extending the lifespan of concrete structures, showcasing its potential in the experimental stage for the future of civil engineering.

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Our next issue will look at Co-Benefits of the Built Environment (COBE), research out of Harvard, Boston University, and Oregon State University on the health benefits of energy efficiency. As always, email us your thoughts and follow us on X @CivilWire and LinkedIn.

Until next time; happy goal crushing.