Cement and Concrete: An Infinite Variety
Used in ancient Egypt, cement and concrete are among the oldest construction materials in human history. Today, they are also among the newest and most innovative, and they keep evolving. Cement and concrete products come in a wide variety of forms and applications, and new formulas and uses are discovered every year. New additives for both cement and concrete are making them more versatile and adaptable, widening the range of uses and improving their properties, such as strength, electrical conductivity, and even pollution control.
Classic cement and concrete, of course, will always form the backbone of the industry. But research continues into cement and concrete for specialized uses. There are now cork-cement composites, mudcrete for road bases and land reclamation, glass concrete for aesthetics, rubberized concrete, polymer concrete, geopolymer green concrete, limecrete, strong and light hempcrete with good insulating properties, papercrete, and smog-eating concrete, with more to come.
New types of concrete made by including various kinds of fibres in the initial mix are particularly useful. Reactive powder concrete is a high strength ductile material formulated from a special combination of constituent materials. It includes steel or polymer fibres that make it five times as strong as regular concrete. A bridge made of Reactive Powder Concrete may not require reinforcing steel bars, making it much lighter and also longer-lasting than traditional designs. Reactive Powder Concrte was used at a light rail transit station in Calgary for the platform roof and its supporting columns.
Conductive concrete includes steel or carbon fibres to create pavement or building material that conducts electricity. Unlike the process of embedding wires or sensors in traditional concrete, the addition of fibres does not degrade mechanical properties or durability. Potential uses include heating sections of a roadway or runway to melt ice during winter, floor heating and monitoring in buildings and military applications. The ice-melting potential of conductive concrete is being used on the Roca Spur Bridge near Lincoln, Nebraska.
Translucent concrete is still in the early stages of development. It is made by embedding glass fibres or plastic mixtures with various binding agents into traditional concrete. Thin slabs of translucent concrete could actually allow passage of light through a wall, opening up new possibilities for buildings.
Self-compacting concrete is designed to reduce the labour required for laying concrete slabs. It contains superplasticizers that keep the concrete fluid so it can consolidate under its own weight without mechanical vibration. As a result, a slab of 60 cubic metres requires four man-hours of work for installation as compared to about 64 man-hours for regular concrete.
Smog-eating cement was named one of TIME Magazine's Best Inventions of 2008. Ordinary cement is mixed with a photo-catalyzer (titanium dioxide) that speeds up the natural process that breaks down smog into its component parts. Developed by an Italian firm over a period of 10 years, the smog-eating cement was used to make concrete for a busy street in