Question 4

Listen to the recording: Concrete is the backbone of modern infrastructure, yet it suffers from a fundamental flaw: it cracks under stress. These fissures allow moisture to penetrate and corrode the steel reinforcement, compromising stability. To counter this, researchers have engineered a new type of concrete containing dormant bacteria. When cracks form and water seeps in, the bacteria awaken and generate limestone, sealing the gap. This autonomous repair process means that in the future, our bridges and roads could essentially heal themselves without ...