Determination of Thermodynamic Data and Chemical Structure for Zeolites

https://sasp20.empa.ch/documents/55996/14345359/New+2020+Zeolite+Chart.jpg/482edf9e-8c8f-4683-a91c-99330cdf5c4f?t=1599640187000
Predominance diagrams for zeolite (light green), cement (light blue), and clay (light yellow) phases in CaO-SiO2-Al2O3-H2O chemical system saturated with respect to portlandite at 25 °C

Zeolites are widely used in areas as diverse as petrochemical industries, agriculture, and as supplementary cementitious materials. Zeolitic precursors are also formed in the interaction zone between cement and clay rocks, in alkali-activated cements, at the surface of cements exposed to seawater and during carbonation. Due to their high structural variability in terms of the Al/Si and extra-framework cations, their stability is poorly known, which leaves a serious gap in thermodynamic data and thus disables reliable predictions on their durability at the interaction zone of cement with the environment. The solubility of zeolites with different Al/Si ratios and cations (Na, K, and Ca) are measured at different temperatures. The experimentally derived solubility data allow predicting under which conditions zeolite might forms, facilitating understanding the formation conditions. The binding of Na+, K+, Al3+ and/or heavy metal in zeolites can contribute to counteract and prevent the expansive alkali silica reaction or to slow down the transport of heavy metals. Prof. Dr. Barbara Lothenbach and Dr. Bin Ma are investigating this topic in the Group Cement Chemistry and Thermodynamics.

 

Project Period

April 2018 - July 2021

Additional information
https://sasp20.empa.ch/documents/55996/14345359/New+2020+Zeolite+Chart2.jpg/6f05184a-ad3e-47d5-8eda-249e788c700d?t=1599640214000
Team

Project Leader

Barbara Lothenbach

Team

Bin Ma


Partner

Paul Scherrer Institut

 

Funding Organization

Empa (Distinguished Senior Researcher grant)

EU Horizon 2020 (Marie Skłodowska-Curie grant)

Nagra


Publications

Synthesis, characterization, and thermodynamic study of selected Na-based zeolites

Thermodynamic study of cement/rock interactions using experimentally generated solubility data of zeolites