Self-healing concrete

    The idea is to develop a self-healing concrete, which could cut building costs by reducing the amount of steel needed to add structural support.
    Under strain, concrete will develop cracks that will eventually spread and weaken the structure. Why not mix the spores of limestone-producing bacteria and some nutrients into the concrete material. The spores will remain dormant until they are activated by rainwater, at which time they will eat the nutrients and produce limestone, filling the tiny cracks before they can spread.