Steel (Reinforcement Bars)

Steel is a cornerstone of modern construction and can be found in almost every modern building and vehicles. Its key components are iron and carbon, but other metals can be added to make different steel alloys (e.g. addition of Chromium to form stainless steel). Its main application in civil engineering is as reinforcement bars (rebar steel) to strengthen concrete structures, but it is also used as structural steel and sheet products. While steel is an essential building material due to many beneficial properties, its production is highly energy- and carbon-intensive.  Circular economy strategies aim to mitigate this impact. In manufacturing, refuse strategies include substituting rebar steel with bamboo or fibre-reinforced polymers, though these are still in the experimental phase. Rethink strategies involve designing concrete elements for easier disassembly and using corrosion inhibitors to extend rebar life. Reduction is achieved by using higher-strength steel, which can reduce material use by up to 24%. Recycling is already widespread, with rebars being tolerant of impurities, making them ideal for incorporating scrap steel.

At the end of life, reuse of rebars is limited due to their embedment in concrete, but selective demolition can enable reuse in some cases. Recycling is the dominant strategy, with up to 95% of rebars being recycled in some European countries. However, quality control is essential to manage impurities that accumulate over multiple recycling cycles.