Open Access

Janis Moye, Sylvia Keßler, Patrick Sturm

• Supplementary cementitious materials (SCM) are promising alternatives for the reduction of CO2 emissions in the cement industry. Despite extensive research, their adoption, using Germany as an example, remains low due to potential disruption in manufacturing processes and standardization issues. Furthermore, the precursor output rate of e. g., fly ash and ground granulated blast furnace slag (GGBFS) is limited not only due to general cement substitution but for shortages in their respective industries. As a result, SCMs may only serve as a viable alternative binder in niche applications, such as concrete maintenance and repair. Additionally, the use of dry activators such as Na2CO3 facilitates conventional production methods. This paper discusses results of sodium carbonate-activated slag mortars that were applied to concrete reference plates (A3-type as described in “Technische Regel Instandhaltung von Betonbauwerken,” eng. technical guideline for maintenance of concrete structures). The performance of alkali-activated slag (AAS)Supplementary cementitious materials (SCM) are promising alternatives for the reduction of CO2 emissions in the cement industry. Despite extensive research, their adoption, using Germany as an example, remains low due to potential disruption in manufacturing processes and standardization issues. Furthermore, the precursor output rate of e. g., fly ash and ground granulated blast furnace slag (GGBFS) is limited not only due to general cement substitution but for shortages in their respective industries. As a result, SCMs may only serve as a viable alternative binder in niche applications, such as concrete maintenance and repair. Additionally, the use of dry activators such as Na2CO3 facilitates conventional production methods. This paper discusses results of sodium carbonate-activated slag mortars that were applied to concrete reference plates (A3-type as described in “Technische Regel Instandhaltung von Betonbauwerken,” eng. technical guideline for maintenance of concrete structures). The performance of alkali-activated slag (AAS) mortars was evaluated in terms of shrinkage behavior, compressive, flexural, and adhesive strength after dry thermal cycling and thunder-shower cycling. Interestingly, the results showed enhanced strength after exposure to these experimental conditions in comparison to ambient temperature curing. This highlights the critical role of proper curing, as AAS mortars are highly susceptible to increased shrinkage when not exposed to sufficient moisture. The previous results show that AAS mortars - even without optimization - meet the required properties for structural repair class “R3” as defined in DIN EN 1504-3, promoting SCMs as promising alternative binders for these practical use cases.…