A recent research shows that adding Bacillus megaterium to concrete enables it to self-heal cracks and resist sulfate attack, boosting strength by over 40% and restoring up to 93% of its original capacity, offering a durable and eco-friendly solution for infrastructure.
Concrete is the backbone of our cities—holding up bridges, roads, skyscrapers, and dams. But like any hero, it has a weakness: cracks. Whether caused by heavy loads, temperature changes, or chemical attack, cracks let in water and aggressive ions like sulfates. Over time, these intruders weaken the structure, corrode steel reinforcements, and force costly repairs.
In sulfate-rich environments (think coastal areas, sewage systems, or industrial zones), the problem is worse. Sulfates react with cement paste, forming expansive minerals like ettringite and gypsum—pushing the concrete apart from the inside. Imagine concrete swelling until it bursts. Not pretty.
That’s where a fascinating innovation steps in: self-healing concrete powered by bacteria. And in this study, researchers from Egypt explored two bacterial superheroes—Bacillus megaterium (BM) and Bacillus sphaericus (BS)—to see how well they could fight sulfate attack and repair cracks on their own.
Self-healing concrete isn’t sci-fi anymore—it’s a real material. The trick is microbially induced calcium carbonate precipitation (MICP). Here’s how it works:
The beauty? Bacterial spores can survive in concrete for centuries. That means the self-healing effect can last as long as the structure itself.
The study mixed bacteria into concrete at 1% and 2.5% of cement weight—both with and without pozzolanic materials (silica fume or fly ash). They then cured the samples in either fresh water or sulfate solutions (2%, 5%, and 10%) to mimic mild, aggressive, and extreme sulfate exposure.
They measured:
SEM images told the story visually:
EDS analysis confirmed lower Ca/Si ratios in healthy bacterial concrete—meaning more calcium was locked into strong C-S-H gel rather than forming weak, expansive compounds.
Concrete is the second most used material in the world after water—but also one of the biggest CO₂ emitters. Frequent repairs and rebuilds make its environmental footprint even worse.
Self-healing concrete offers:
By combining bacteria + pozzolanic waste materials (like silica fume and fly ash), this study shows we can make concrete both greener and tougher.
The research proves bacterial self-healing concrete works—not just in lab conditions but also in sulfate-rich environments. Here’s what’s next:
This study shows that tiny bacteria can solve one of concrete’s biggest problems—and do it sustainably. Bacillus megaterium, in particular, not only repairs cracks but also protects against sulfate attack, making structures last longer with less environmental impact.
The numbers speak for themselves: +41% strength, 93% healing efficiency, and resilience in harsh chemical environments.
In the not-so-distant future, we might see bridges that fix themselves overnight, harbors that resist seawater attack for decades, and roads that outlive the cars driving on them—all thanks to a microscopic workforce living quietly in our concrete.
So next time you walk past a massive concrete wall, just remember—there might be a colony of bacteria in there, keeping it healthy.
Self-Healing Concrete - Concrete that can repair its own cracks using natural or engineered processes—like having a built-in repair crew.
Bacillus megaterium / Bacillus sphaericus - Friendly, spore-forming bacteria that survive in concrete for decades and produce minerals to seal cracks.
Microbially Induced Calcium Carbonate Precipitation (MICP) - A natural process where bacteria produce calcium carbonate (CaCO₃) crystals that fill cracks and pores.
Pozzolanic Materials - Industrial by-products (like silica fume or fly ash) that react with cement to make concrete denser and stronger.
Calcium Carbonate (CaCO₃) - A common mineral (limestone) formed by bacteria in self-healing concrete to seal cracks. - More about this concept in the article "Revolutionizing Soil Stabilization: Wastepaper and Microbes Unite!".
Sulfate Attack - A chemical reaction where sulfate salts in soil or water attack cement paste, causing swelling, cracking, and weakening.
Silica Fume - An ultra-fine powder from silicon production—used in concrete to fill tiny voids and boost strength.
Fly Ash - A fine powder from coal combustion—used to improve concrete durability and reduce waste.
Compressive Strength - How much squeezing force concrete can take before it breaks—key for load-bearing structures.
Flexural Strength - How much bending or stretching force concrete can handle before it cracks.
SEM (Scanning Electron Microscope) - A super-powerful microscope that shows concrete’s surface in extreme detail.
EDS (Energy Dispersive X-ray Spectroscopy) - A tool that tells what elements are in a material—used to check chemical changes in concrete. - More about this concept in the article "Cracking the Code of Smart Fertilizers: A Deep Dive into Biosolid Innovation".
XRD (X-ray Diffraction) - A technique to identify crystals and minerals inside concrete, like calcite or gypsum.
AbdElFattah, I.; Ahmad, S.S.E.; Elakhras, A.A.; Elshami, A.A.; Elmahdy, M.A.R.; Aboubakr, A. Bio-Mitigation of Sulfate Attack and Enhancement of Crack Self-Healing in Sustainable Concrete Using Bacillus megaterium and sphaericus Bacteria. Infrastructures 2025, 10, 205. https://doi.org/10.3390/infrastructures10080205
From: Zagazig University; Housing and Building National Research Centre; Misr Higher Institute of Engineering and Technology; The Higher Institute of Engineering and Technology.
