The production of cement used in concrete is thought to be responsible for 5-8% of global carbon dioxide emissions, but a new approach to making cement has the potential to reduce both greenhouse gas emissions and water consumption. In its raw state, concrete dust is environmentally friendly, as it is a natural component. However, it is in the industrial extraction of the materials, the mixing and application of the concrete that it is no longer considered eco-friendly. Concrete floors, dyed with non-toxic pigments, are a healthier alternative to carpets because they do not emit harmful VOCs and are easy to sweep.
In fact, VOC emissions from concrete building products are much lower than most other building materials, according to the Portland Cement Association (PCA). The use of natural lime-cement wall finishes and concrete countertops can also significantly reduce total VOC concentrations inside a home. The most widely used building material on the planet, it has given us sculptural buildings, sturdy bridges and dams, car parks and countless other structures that surround us. But concrete is also responsible for about 8 per cent of the world's carbon emissions.
If concrete were a country, it would rank third in terms of emissions, behind China and the United States. I could go on, but seeing concrete described as "ugly and grey, environmentally unfriendly" suggests that the author already has a fixed opinion. Therefore, it is important to consider all aspects of concrete production and use in order to determine if it is truly an eco-friendly building material. The European concrete industry has taken steps to reduce its CO2 emissions, making an important contribution to climate problems. The use of leftover concrete is a smart way to utilise concrete waste material and reduce the resource consumption of the concrete production process.
Central recently used CarbonCure technology for the concrete it supplied to LinkedIn for the 245,000 square foot headquarters the networking company is building in Mountain View, California. The lifespan of concrete building products can be double or triple that of other common building materials. Only in its most natural state can concrete be said to be environmentally friendly, and only as a powder can it be degradable. Four different concrete materials made from three different blast furnace slag (BYF) and ordinary Portland cement (OPC) cements were used in small-scale models in Romania, Spain and the UK and in a test plant in Spain.
Although concrete produced with plastic waste provides a strength within a specific limit, it is unquestionably an environmentally friendly alternative to traditional concrete. The Sustainable Production of Concrete (SPC) has expressed strong support for the European Carbon Border Adjustment Mechanism (CBAM) as a means of protecting the industry against imports from both neighbouring non-EU countries and polluting transport from concrete exporters abroad, such as in Turkey. In mid-May this year, HeidelbergCement completed a Concrete Sustainability Council (CSC) certification campaign at the 10 concrete plants, 12 concrete factories and five aggregate sites that underwent the certification process. In addition to finding substitutes for cement, replacing aggregate materials with recyclable and reusable resources is an effective strategy used to minimise greenhouse emissions caused by traditional concrete. However, the lower calcium content, lower combustion temperature and lower energy demand for grinding result in approximately 30% less CO2 emissions associated with concrete production. There is not much waste created by unused concrete, except perhaps in small quantities by over-enthusiastic DIYers.
More than 4 million tonnes of concrete are produced each year, accounting for approximately 8 per cent of global CO2 emissions. Concrete production is a difficult and complex industry, involving the processing of limestone and clay in powerful kilns.