Carbon dioxide sequestration of fly ash alkaline based mortars with recycled aggregates and different sodium hydroxide concentrations: Properties, durability, carbon footprint, and cost analysis

This chapter discloses results of an investigation concerning carbon dioxide sequestration on fly ash/waste glass alkaline-based mortars with recycled aggregates and different sodium hydroxide concentrations. Properties, durability, carbon footprint, and cost analysis were studied on it. Mixtures using a sodium hydroxide concentration of 8M and the additive calcium hydroxide show the best performance and the lowest carbon footprint. Simulations using a carbon tax of 0.0347 Euro/kg show no influence on the cost of the mixtures while the use of the carbon tax of 0.206 Euro/kg show an increase in the cost-efficiency of mixtures, even those using a sodium hydroxide concentration of 8M and additive calcium hydroxide.The authors would like to acknowledge the financial support of the Foundation for Science and Technology (FCT) in the frame of project IF/00706/2014-UM.2.15.info:eu-repo/semantics/publishedVersio

Carbon dioxide sequestration on mortars containing recycled aggregates: A hot area for startup development

The world is closer to exceeding the budget (cumulative amount of anthropogenic CO2 emission compatible with a global temperature-change target) for the long-term target of the Paris Climate Agreement than previously thought. Three lines of evidence suggest that global warming will be faster than projected in the recent IPCC special report.  First, greenhouse-gas emissions are still rising. Second, governments are cleaning up air pollution faster than the IPCC and most models previously assumed. But aerosols, including sulfates, nitrates and organic compounds, reflect sunlight so the aforementioned cleaning could have a warming effect by as much as 0.7 ºC. And in third place, there are signs that the planet might be entering a natural warm phase because the Pacific Ocean seems to be warming up. And these three forces reinforce each other. Carbon dioxide sequestration is therefore crucial for targets for limiting global warming. Europe is now putting great efforts and funding in carbon sequestration materials and technologies. The flagship programme EnCO2re, currently looks to develop new technologies offering novel ways to use CO2; increase awareness for CO2 re-use; and ensures sustainability and social acceptance of materials and products by integrated socio-ecological research. Also Carbon capture and sequestration is one of the 100 Radical Innovation Breakthroughs for the future (Europe, 2019)..This chapter discloses results of an investigation concerning the performance of fly ash/waste glass alkaline-based mortars with recycled aggregates reinforced by hemp fibres. The results show that hemp fibres lead to a reduction of mechanical properties of alkali-activated materials.Foundation for Science and Technology (FCT) in the frame of project IF/00706/2014-UM.2.1

Alkali-activation potential of biomass-coal co-fired fly ash

Co-fired fly ash, derived from the co-combustion of coal and biomass, is examined as a potential precursor for geopolymers. Compared to a coal fly ash, two co-fired fly ashes have a lower vitreous content and higher carbon content, primarily due to differing combustion processing variables. As a result, binders produced with these co-fired fly ashes have reduced reaction potential. Nevertheless, compressive strengths are generally highest for all ashes activated with solutions with a molar ratio of SiO₂/(Na₂O + K₂O) = 1, and these mixes reach the highest extent of reaction among those studied. Activation with sodium hydroxide solution forms zeolitic phases for all ashes. The thermal and dilatometric behavior of the coal and co-fired fly ash geopolymers is similar between equivalent mix designs. These results indicate that co-fired fly ashes can be viably used to form alkali-activated geopolymers, which is a new beneficial end-use for these emerging waste materials