Helping Concrete Heal Itself

Abstract

Concrete is one of civilization’s most durable building materials. The ancient Romans used concrete 2,000 years ago to make structures that still stand today. People now use the material’s modern version—aggregates such as sand or gravel held together by a cement and water paste—more than all other construction materials combined. The world produced 4.3 billion metric tons of cement in 2014, and this production will keep increasing as more sidewalks, buildings, and bridges get built in an increasingly urban world. For all its strength and durability, though, concrete has problems. Stress from carrying loads gradually creates microscopic fissures in the material that allow in water, salts, and ice. These fissures can then turn into gaping cracks, exposing the steel bars often used to reinforce concrete to corrosive elements. Our seemingly resilient infrastructure would crumble without routine, and costly, patching. To reduce those maintenance costs and make buildings and bridges safer,