Concrete, which is cement mixed with water and mineral aggregates, is a strong and long-lasting building material allowing a high flexibility in form and application. This results in cement being the largest manufactured product on Earth by mass. It is produced from widely available materials, but the related burning of fossil fuels as well as the calcination of raw materials contribute up to 5% of the global anthropogenic carbon dioxide emissions. The majority of cement used today is Portland cement, which is grinded clinker containing alite (Ca3SiO5; 50-70%), belite (Ca2SiO4; 15-30%), aluminate (Ca3Al2O6; 5-10%) and ferrite (Ca2AlFeO5; 5-15%). Another cement is calcium aluminate cement (CAC). The hydration process after water contact leads to calcium silicate hydrate (CSH) and calcium aluminate hydrate (CAH) phases resulting in a fast and slow mode of strength development. The aim is to reduce the amount of clinker necessary preserving at the same time its initial strength, workability and long-term stability. For this reason, it is crucial to gain exact knowledge of the different crystal structures present in the cement as well as the stable and meta-stable hydration products occuring during the hardening process.
In the case of Belite it was already possible to retrieve the unknown structure of the key polymorph, the incommensurate α'H phase, using ADT allowing to explain the genesis of the low temperature modification through cooling. Alite is known to contain superstructures, intergrowth and disorder. The class of CSH and CAH (materials of interest in this project) are beam sensitive and dedicated data acquisition strategies need to be developed. In addition, these layered materials develop disorder effects as well as superstructures that need to be characterized. The already available routines to process the total scattering information of 2D defects and to quantitatively analyse stacking faults will be applied and optimized.