Overall, roughly a quarter of global greenhouse gas emissions are associated with the production of structural materials. Among those, approximately 7% are linked to the production of cement, which is one of the key ingredients in concrete, although it only counts for 10% of the concrete mix. Over the last 50 years, the worldwide production of cement has increased almost tenfold. In light of that number – which does not account for the other components of reinforced concrete- and in order to meet the requirements of the Paris Agreement, there needs to be a significant reduction of the carbon impact of the construction industry.
Arup has led an initiative to provide recommendations on how to improve concrete mixes and reduce their Global Warming Potential (GWP). This paper presents the highlighted recommendations and presents as a case study the results obtained from a project that followed these recommendations. The case study involved the replacement of rail platforms using low-carbon precast curb units. A review of key factors and avenues to improve the carbon impact of concrete mixes is presented and recommendations are given. The application of those recommendations and their impact on the project are discussed. Setting environmental targets allowed a reduction of the GWP of the concrete mix used by 50% compared to the average in the precast concrete industry, without inducing costs or delays. The success of the initial project has led to these recommendations being used on a subsequent platform project at a different site.
Keywords: Sustainability; Global Warming Potential; Fly Ash; Precast concrete
