Project: overview

Concrete is the World’s second most consumed material after water and is used in almost all building structures. However, its high environmental impact must be recognized; the cement industry accounts for 6% of the total global carbon dioxide emissions and is increasing. If this amount were gathered and spread across the entire area of Portugal, it would be 3 m high. In parallel, Portugal produced 4.71 Mt of municipal solid waste (MSW) in 2014, 20% of which were incinerated with energy recovery. Despite being vital for the correct management of MSW, it is responsible for two by-products: MSW incinerated fly ashes (MIFA) and bottom ashes (MIBA). About 100 kt/year of MIBA come from Valorsul’s incineration unit, treating most of Lisbon’s MSW and supporting the project, whereas MIFA is solidified/stabilized using cement and sent to a landfill. MIBA are transformed into a value-added product, which is used in road construction, but it is of interest that the scope of the material’s application is widened.

To comply with the recently signed Paris Agreement, and to mitigate global warming, further measures must be undertaken to reduce the cement industry’s carbon dioxide emissions with the introduction of technically viable alternatives. Furthermore, in view of the scarcity of outlets for MSW ashes (MSWA), there is significant scope for the development of value-added applications for them.

These issues can be tackled with the alkali activation of MSWA to produce new binding systems. Stakeholders from various markets are gradually aware of the progress of non-Portland binder systems, with alkali-activated materials (AAM) as the top contenders. Early studies have shown the feasibility of AAM, in high-strength precast beams, columns, and slabs, based on activated fly ash (FA) or blast furnace slag (BFS) as the only binders. Since MSWA also exhibit high activation potential, a unique opportunity emerges to valorise them into a monolithic construction material capable of encapsulating their hazardous elements.

Taking advantage of the team’s vast knowledge on the matter, previously demonstrated in 3 books and over 120 papers on non-traditional cement-bound materials in ISI/Scopus databases, this project seeks to maximize the activated MSWAs’ performance, by optimizing the alkaline activator and precursor compositions and establishing ideal curing regimens to enhance its properties. With the environmental impact minimization, by using an alkali-activated cement-free binder and fully replacing natural aggregates with recycled ones, an evaluation will be carried out concerning RInoPolyCrete’s practical implications, including life cycle assessment and life cycle cost. After patenting the product and ensuring its safe use, further measures will be discussed with the research team’s partners to introduce the material in a real application serving as a gateway for its future commercialization.