Lasting homes

Homes in the future could last forever. Well, almost! A concrete material developed at the University of Michigan can heal itself when it cracks. No human intervention is necessary—just water and carbon dioxide to heal and form a thin white scar of calcium carbonate.

Self-healing is possible because the material is designed to bend and crack in narrow hairlines rather than break and split in wide gaps, as traditional concrete behaves.

Failures often occur when traditional concrete is strained in an earthquake or by routine overuse as it is brittle and rigid. But the flexibility of engineered cement composite, or ECC (which acts more like metal than glass), prevents this occurrence. The bendable ECC remains intact and safe up to tensile strains of 5 percent where traditional concrete fractures and can’t carry a load at .01 percent tensile strain.

At present, building structures are constructed using steel bars to keep cracks as small as possible. But they’re not small enough to heal, so water and salts can penetrate to the steel, causing corrosion that further weakens the structure. Self-healing concrete needs no steel reinforcement to keep crack width tight, so it eliminates corrosion. And costs! And energy!

Natural materials have long been shown to be the best when it comes to temperature modulation and costs. Bamboo, kemp, etc have been used effectively. But more and more traditional homes all over the country are being replaced by concrete structures – for its strength. Are we headed in the right direction?