Low carbon cements towards the consolidation of porous substrates

In the last ten years many countries set up ambitious goals of carbon neutrality to tackle global warming and to regulate the industries that emit large amounts of greenhouse gases. Among that, we find the cement industry, accounting for about 7% of the global CO2 emissions. Recently, the green supply chain (waste-to-resources) has been established to realize a circular economy, involving the use in the cement industry of more and more alternative raw materials originating as byproducts or wastes from other industries. Among all the possible eco-friendly cementitious material that can be used to partially replace Portland cement or as alternative binders, we find ground granulated blast furnace slag (GGBS). GGBS is a glassy byproduct of pig iron and steel production, with pozzolanic properties strictly related to its variable composition. GGBS is already employed in many applications, including the stabilization of soils, the preparation of cementitious blends with low environmental impact, the formulation of unfired clay bricks and the design of bioreceptive environmentally friendly concretes. Aiming at exploring new applications for low carbon cements, we decided to study some innovative systems, whether seeking at the development of binders with adequate bio-colonization properties, or to develop consolidation treatments that could extend the life cycle of other materials. In particular, we recently investigated some GGBS water-based dispersions whose hydraulic properties were boosted by the use of Ca(OH)2 nanoparticles, allowing for the obtainment of formulations that can be used for the reinforcement of porous substrates. To this purpose, different formulations were thoroughly characterized and the best one was tested for the consolidation of adobe, one of the most popular earth-based masonry materials despite its high susceptibility to weathering.