Infrared spectroscopy-based characterization of cement phase dissolution rates (IRCEMDIR)

• Applicant: Professor Dr. Torben Gädt
• Subject Area: Construction Material Sciences, Chemistry, Building Physics
• Term: since 2026
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 579558866

The chemical reaction of Portland cement with water to form hydrated cement phases is responsible for the mechanical strength of concrete. The rate of this reaction, also called cement hydration, is crucial for both the handling and placement of fresh concrete, as well as for the engineering properties of the hardened concrete. However, our understanding of the mechanism of cement hydration is still incomplete. The rate of the first step of cement hydration, i.e., the dissolution step, has been a focus of research in recent years. Unfortunately, the necessary methods to study the dissolution rate all have significant drawbacks. They either rely on expensive and rarely available methods, such as digital holography or vertical scanning interferometry, or, in the case of simple batch dissolution experiments, have changing supersaturation conditions and issues with reliable quantification due to the often very low ion concentrations involved. Therefore, we propose to develop a method based on readily available instrumentation that circumvents the central problems with existing methods. The key objective of the project is the combination of a flow-through cell with a standard infrared spectroscopy (IR) instrument. IR spectrometers are relatively inexpensive, widely available in many labs, and highly robust in their operation. Furthermore, a flow-through cell allows the use of solutions with constant ion concentrations, which facilitates systematic variations of the undersaturation of the aqueous solution with respect to the dissolving phase. Furthermore, we will systematically measure the dissolution rates of cementitious phases at variable solution conditions. This data will be used to validate the new method by comparing our results with dissolution rates obtained using other methods. Furthermore, the new method will enable a high experimental throughput, thereby significantly increasing the available knowledge on cement dissolution rates. For example, we will systematically study the influence of extrinsic ions on the dissolution rate of the most important cement phases. Finally, the project will focus on the structure-activity relationship of superplasticizers and their effect on inhibiting the dissolution rates of tricalcium silicate (C3S) and tricalcium aluminate. Superplasticizers are essential polymers in modern concrete, enabling the reduction of water, as well as the decrease in cement, cost, and CO2 emissions associated with concrete production. However, these polymers, which primarily act as dispersants, also have a side effect, i.e., they influence the rate of cement hydration. This has been partly ascribed to their inhibiting influence on the dissolution rate of C3S. We will synthesize a library of polymers and investigate their impact on the dissolution rate.

• DFG Programme: Research Grants