Cementing concrete’s place as a sustainable building material
Strong, durable, efficient and safe, concrete is by far the world’s construction material of choice. According to ‘Nature’, 30 billion tonnes of concrete is used worldwide every year. In fact, the BBC estimates that concrete accounts for nearly half of all human-made things and that there’s so much concrete that it will soon outweigh all living matter on Earth. The problem with all this concrete is that it comes with a rather substantial carbon footprint. As ‘The Guardian’ reports, concrete is responsible for between 4 % and 8 % of the world’s annual CO2 production. The bulk of concrete’s emissions comes during the manufacturing of Portland cement clinker, one of the main materials used to make cement. “Producing clinker consumes significant amounts of materials and energy,” says Arnaud Muller, a senior scientist at HeidelbergCement. “For this reason, most efforts to reduce concrete’s carbon footprint have so far focused on decreasing the clinker part.” Supplementary cementitious materials, or SCMs, have become the standard substitute for part of the clinker. “While SCMs succeed at reducing material and energy use, the end product – the concrete – might lack the performance and durability of traditional concretes,” adds Muller. With the support of the EU-funded EnDurCrete project, HeidelbergCement led a group effort to develop a cost-effective concrete that is both sustainable and durable. To do so, the project turned to technology.
Increasing the service life of concretes
Instead of just looking to the material use, EnDurCrete focused on all available routes to increase the service life of concretes. “By extending the service life of concrete and the structures using it, we can decrease the amount being made – which is where the majority of emissions occurs,” explains Muller. The project started by developing novel low clinker cements and concretes. The entire consortium then conducted extensive laboratory studies to better understand the factors that cause concrete damage. “Not only did we want to develop new, greener concretes, but we also wanted to understand how we could go beyond current limits and extend performance while also improving sustainability,” notes Muller. One method that researchers used to increase their ability to sense and track damage was the use of carbon-based additives for enhanced electrical conductivity. However, when it was found that the material originally selected did not conform with health and safety requirements in all EU Member States, the team was forced to look for alternatives. “We cannot sacrifice health and safety for sustainability, as they are necessarily linked,” remarks Muller. “Thanks to the dedicated work of the project partners, we were able to identify a suitable alternative that got the results we needed.”
Durable, eco-friendly concretes to become the norm
Based on this initial work, the project added several technologies to EnDurCrete concretes, including self-healing and self-monitoring functions. Brought together into a final concrete element, the EnDurCrete solution is expected to be 40 % more durable than conventional concrete while cutting the global warming potential nearly in half. “As the construction industry looks to become increasingly sustainable, durable and eco-friendly, concretes like the ones developed by the EnDurCrete project will become the norm,” concludes Muller. The EnDurCrete solutions have been tested in real-world demonstrators, including tunnels, harbours and bridges, with some being further developed commercially.
Keywords
EnDurCrete, sustainability, concrete, sustainable building material, construction material, emissions, cement, carbon footprint, clinker, cement, global warming
