Environmental impacts and decarbonization strategies in the cement and concrete industries

Abstract

The use of concrete is under scrutiny as it appears as one of the few human activities where the transition toward a post-carbon society is not possible unless large investments in risky carbon capture and storage are made. With current urbanization, it is also a sector that is expected to continuously grow, leading to increased resource consumption and emissions. In this review, we aim to shed light on the available solutions that can be implemented in the short and long term to reduce greenhouse gas emissions. Rather than waiting for disruptive technologies that could transform a very slow moving and risk-averse construction sector, this review focuses on the small improvements that every stakeholder involved along the value chain of concrete production and use can achieve. We stress how significant the combined effect of these marginal gains can be. By balancing societal needs, environmental requirements, and technical feasibility, the intention of this review is to show credible pathways for a transition to sustainable use of concrete. Key points• Cement usage is so massive, more than 4 billion tonnes per year worldwide, that large-scale replacement by other materials within the next decade is not possible.• Environmental impact of cement and concrete is low per unit of material, but the amount used makes the impact of the sector highly significant.• Reductions in CO 2 emissions are possible through successive improvement all along the cement and concrete value chain: less clinker in cement, less cement in concrete, less concrete in structures, and less replacement of structures.• By engaging all stakeholders of the construction sector, immediate savings of the order of 50% can be reached without heavy investment in new industrial infrastructure or modification of standards.• Research and development need urgently to be conducted for post-2050 construction to meet future emissions reduction targets. Alternative cement and faster carbonation of concrete should be explored.

Engineering living building materials for enhanced bacterial viability and mechanical properties

“…Construction of buildings and infrastructure consumes a lot of resources and contributes to the large-scale production of industrial waste and greenhouse gasses; the production of Portland cement, half of which is used to produce concrete, contributes to 5%-8% of the global CO 2 emission ( Benhelal et al., 2013 ; Shen et al., 2015 ; Habert et al., 2020 ). Utilization of renewable building materials and methods of recycling them are critical for environmental sustainability.…”

The Design of Mass Timber Panels as Heat-Exchangers (Dynamic Insulation)

“…Concrete has traditionally been a source of CO 2 emissions due to its intensive production process, but can reabsorb significant amounts of carbon over its long service life (Cao et al, 2020). Recent advances in manufacturing-tailoring the curing process to absorb more C, or mineralizing the CO 2 from production in the flue for use as aggregate-provide opportunities for carbon utilization in the concrete industry beyond lifetime carbonation (Monkman and MacDonald, 2017;Habert et al, 2020). Meanwhile, biogenic materials like timber and bamboo grow by photosynthesis, sequestering carbon in their biomass.…”

Material diets for Climate-Neutral Buildings

“…using alternative materials with lower embodied emissions 18 . Although these strategies could reduce by 50% the emissions for construction, they cannot reach net-zero emissions 19 . For example, most buildings require cement for concrete foundation or structure and a complete decarbonization is not possible due to energy intensive processes for manufacturing and emissions related to calcination reaction 20,21 .…”

“…In the Global South, bamboo is a promising solution to avoid massive deforestation of tropical forest 26,29 . Nevertheless, concrete will remain the reference material for a majority of construction even though low carbon concrete can be implemented 19 . Definitely, most of carbon intensive materials currently used in construction will be adopted in future, with a influence on the whole building mass sometimes significant 30 .…”

“…Finally, it's important to mention that the GHG-fossil emission linked to the use of concrete could be further reduced by implementing low-carbon concrete. We used in this paper conventional concrete emissions but available alternatives allow to reduce by a factor-two these emissions 19,50 . This would reduce by the same order of magnitude the insulation volume and therefore lead to the possibility of building concrete climate-neutral buildings with similar wall dimension as current construction.…”