Team A–Z

Responsibilities

My research concentrates on the understanding of homogeneous crystallisation processes of calcium silicate hydrates (C-S-H), which is the most important compound in modern cement. The main focus lies here in the pre-nucleation and early post-nucleation regime. Further, the influence of zinc on the nucleation of C-S-H is investigated, since it’s one of the most common impurities in cement. Another topic is the influence of dehydration processes (e. g. due to cosmotropic/chaotropic effects) on pre-nucleation species of C-S-H and the altering on its nucleation pathway. In general, all C-S-H is synthesised with simple silicon and calcium precursors via automated titration set-ups.

The crystallisation process is in-situ monitored with different electrodes and the obtained solid & pre-nucleation species are respectively analysed with the following methods: FT-IR, PXRD, TGA, SEM/EDX & (HR)TEM/EDX/ED, AUC, ToF-MS.

Responsibilities

Physical Chemistry

Towards sustainable cements: Understanding the crystallization of cementitious hydrates in LC3 blends as eco-friendly binder

Limestone calcined clay cements (LC³) are a very special and promising type of new cements. They take advantage of synergistic effects in the interaction of calcined clay and limestone as supplementary cementitious materials. With these cements it is already possible to reduce the clinker content to less than 50% and thus save more than 30% in CO₂ emissions. Additionally, LC³ blends are roughly 15-25% cheaper in production than ordinary Portland Cement (OPC). However, one of the few disadvantages still lies in the rheology of calcined clay-containing materials. Once water has been added, they are not as easy to handle as traditional Portland cement, making them somewhat more difficult to work with on the construction site. 

This is where the research of Yannick Emminger comes in and tries to find a way to firstly investigate and secondly influence the crystallisation of the different hydrates in LC³, making it more applicable for construction. Hereby, the hydrates (C-S-H, C-A-S-H, ettringite, calcium carboaluminates, AFm and AFt phases,...) are synthesised via a precipitation reaction from an aqueous solute phase and subsequently analysed. The aim is to monitor the nucleation and control it through additive assistance. For that, analytical methods like FTIR, SEM, EDX, TEM, SAED, TGA, ITC, XRD, DLS, AUC, 1H-/ 13C-/ 27Al-/ 29Si-NMR, and more, are used.