Optimizing binders with slag or fly ash for improved sulfate resistance
The project investigates the sulfate resistance (SR) of cementitious binders containing additions (SCM), a significant durability and sustainability issue for the concrete construction industry. The major focus is on the role of the sulfate balance in the cementitious blend and the re-adjustments needed when using different types or amounts of SCM.
Aim and goal
Study the effect of the sulfate balance in blended binders, on the chemical and structural degradation during sulfate attack. Investigation of blends with slag or fly ash to understand how these SCM can improve the sulfate resistance of non-SR cements.
SCM can improve the sulfate resistance of blended binders when combined with a certain cement but not with another. Addition of SCM changes the sulfate-to-alumina ratio and new types of cement hydrates will form in the blend, depending on the cement and SCM used. But a re-adjustment of this sulfate balance in the blend may be required to ensure an improvement of the sulfate resistance, otherwise it may even be reduced.
A re-adjustment of the sulfate level is required to stabilize hydrate products that will be stable, not lead to expansion, during a sulfate attack. This will be studied through exposure experiments and micro- and macrostructural investigations. Investigating the effect of sulfate level adjustments in different cement+SCM blends will show how the sulfate level could be tuned to obtain binders with improved sulfate resistance.
Binders with increased durability to sulfates will lead to concrete infrastructures having longer service life in environments with high external sulfates, e.g. sea water. Increased knowledge on how we can use larger amounts of cementitious additions and lower amounts of plain cement per m3 concrete, to reduce the CO2 emissions and overall environmental impact associated to the concrete industry.
RISE role in project
2 100 000 SEK