One of my recent articles focused on bendable concrete, presenting it as a big improvement to conventional concrete’s frequent failures. These failures lead to repeated infrastructure and building repairs, using enormous quantities of material and energy and producing large quantities of greenhouse-gas emissions (GHG).
Engineered cementitious composites (ECC), the technical name for bendable concrete, gains its flexibility and durability from polyvinyl fibers covered with a thin (nano-thick), slick coating that allows for slipping rather than fracturing when placed under stress. As ECC is gaining acceptance, research and empirical evidence is demonstrating that the microfibers and surrounding micro-cracks make the concrete self-healing. When air and moisture migrate into the hairline cracks, self-generating reactions of carbon mineralization occur, binding the micro-cracks together. Basically, calcium ions inside the cracked concrete combine with moisture and carbon dioxide from the air, creating a calcium carbonate material similar to seashells.
For some decades, the concrete industry has been trying to reduce its carbon footprint. One of the most successful strategies has been substituting fly ash, rice husks, or silica fume for cement, the main culprit in concrete contributing to GHG. This substitution reduces carbon emissions by essentially the same proportion as the cement is reduced. Many mixes replace 50 percent or more of the cement yet yield a stronger concrete. Fortunately, these substitutions work well in ECC mixes, thus producing greater strength, less carbon emissions, and flexibility.