Let’s get concrete: How can we reduce co2 on a concrete core?

[@PizzaHomie]

I'm curious about the life span of concrete buildings. Because Anders mentions the huge amount of CO2 emission savings associated with recycling precast elements and I would tend to agree. But I wonder, how often would this actually be done? I wonder about the comparison of the lifespan of the concrete building where precast element assembly/disassembly/reassembly is used vs lifespan of the concrete itself.

[@ReconstructingTheWorld]

Of course! It cannot be explained briefly, so prepare for a rather long answer 🙂 According to the report SBI 2019:08 of Aalborg University’s Department of the Build Environment the CO2-emission of 1 m3 new conventional concrete is 343 kg CO2-equivalents. In comparison to this, CO2-emission of 1 m3 the reused precast concrete elements is 13,5 kg CO2-equivalents. This gives a is CO2-reduction of 96%. The numbers of the generic lifespan of concrete building components differs. According to the lifespan table” levetidstabel Version 2021” of AAU’s Department of the Build Environment most of the concrete building components have a lifespan of 120 years. The lifespan of precast concrete elements in most of the Danish Environmental Product Declarations (EPD) is calculated with 100 years. In Norwegian EPDs the lifespan the same material mostly specified with 50 years. 50 years is also lifespan period for precast concrete elements as defined in the concrete guidebook of the Danish Concrete Society (Betonhåndbogen, 12 Beton i bygge- og anlægsbranchen). Until now there is no available standardised lifespan value for reused concrete components. The easiest method to estimate the lifespan would be to calculate the difference between the generic lifespan value for concrete components and the age of the existing building. In practise the reuse of concrete components will normally require test of the technical quality of the material, which can be necessary to insure the expected lifespan of a concrete material. The Danish Technological Institute is working with other companies on a research project called (P)RECAST about the reuse of concrete elements. One of the main purposes of the project is to improve methods for the documentation of the technical quality of reused concrete components. (www.teknologisk.dk/projekter/p-recast/43884)

[@PizzaHomie]

@@ReconstructingTheWorld Cool! Thank you so much for taking the time. I know Katja. I should ask her about what they've learned. I'm sure her and her team at DTI have looked at optimizing the reuse of concrete elements. Not being critical at all. With my comment, I was mostly just being curious with hypothetic scenarios. E.g. If a building is constructed using precast concrete members meant for reuse, and the building lasts for 50 years, 60 years, or more (we are hopefully designing buildings for the long term), surely the components are limited in its future reuse if concrete components have a lifespan of 100 years, conservatively. Thus, I wonder how often these components would be reused. Maybe there are specific applications that would utilize precast concrete member reuse over others.

[@ReconstructingTheWorld]

@@PizzaHomie Yes, we need to stay curious - and most importantly critically curious! Say hi to Katja from us! 🙂