CHALLENGE: CRUMBLING INFRASTRUCTURE LOCATION: WORLDWIDE
Higher concentrations of carbon dioxide in our atmosphere actually accelerate deterioration of concrete. As CO2 penetrates a structure, it reacts with already present moisture and calcium hydroxide, progressively eating away at the layer of cement covering steel reinforcements, leaving them vulnerable to rust. Fortunately, Henk Jonkers, an environmental scientist at TU Delft in the Netherlands, has invented a self-healing version. Jonkers embeds concrete with nitrogen, phosphorus, calcium lactate, and a limestone-producing bacteria. The additives lie dormant until a fissure emerges, admitting air and moisture. Then the bacteria activate, feeding on the calcium lactate, converting it into limestone, and sealing the split.