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Katarina Malaga
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We are building the future now!
COLUMN: Concrete is discussed in many forums today. But few know what concrete really is, what we use it for, and why research into alternative binders for concrete is so important. Katarina Malaga is a professor of sustainable construction and has a PhD in chemical and mechanical decomposition of stone and concrete. In this article, she will providing us with answers.
Cement is the most widely used building material in the world. It consists of 85 percent sand, gravel and water. Cement makes up the remaining 15 percent. Today, cement accounts for seven percent of global CO2 emissions, and four percent of CO2 emissions in Sweden. For Sweden as a country to achieve the goal of carbon neutrality by 2045, an efficient industrial transition is required with sharp emission reductions from the cement and concrete industry, and we need to find an alternative, carbon neutral binder that has the same high quality as cement.
It is estimated that 70 percent of the world’s population will live in metropolitan areas by 2050. The growing need for infrastructure and housing means that concrete use will increase exponentially. But concrete is not just used to build houses, roads, railways and bridges. It is also used, for example, in mines to reinforce rock and in foundations for wind turbines and water and sewage pipes. Concrete is even used in wooden buildings – for the base plate, frames and lift shafts.
RISE has extensive expertise in concrete and cement. We have supported the Swedish concrete and construction industry with research, development, testing and education since the 1940s. The focus has shifted from durability and longevity to consistency and workability for increased productivity and a better working environment. Today, there is full focus on the development of new alternative materials that produce significantly lower climate impact but which retain the same favourable basic properties as those possessed by concrete.
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In the BETCRETE 2.0 project, RISE collaborates with around twenty leading concrete suppliers, construction contractors, industry bodies, and government agencies to produce a carbon neutral concrete for wide market availability as early as 2030, and which will be used as standard throughout Sweden by 2045.
We understand that to significantly reduce emissions, today’s Portland cement (most common type of cement in general use) will need to be mixed with a new binder that produces considerably less or no CO2 emissions. Cement can be mixed with fly ash or slag. This is called climate-enhanced concrete. However, there are technical limitations to the amount of alternative materials that can be used in concrete to guarantee quality. For some applications, we can replace up to 35 percent of cement with slag and for others up to 65 percent. This presents major opportunities to achieve a good climate profile with optimal performance. There are, however, applications for which we have stringent requirements and where we have to use cement that will ensure robust and durable concrete structures for over a 100 years, such as bridges. It is important to identify the right material for the right use and to take the entire life cycle of the material into consideration, not just production. The best building materials are those that last longest.
/Katarina Malaga, professor in sustainable construction
