Mechanism and products of alite hydration in the presence of minerals from the zeolite group

PRELUDIUM 20

Funding Organization: National Science Centre

Project title: Mechanism and products of alite hydration in the presence of minerals from the zeolite group

Agreement number: UMO-2021/41/N/ST8/02458

Project implementation period: 13.01.2022 - 12.01.2026

Principal Investigator: mgr inż. Joanna Styczeń

Project value: 198 132,00 PLN

Funds granted for Lublin University of Technology: 198 132,00 PLN

Abstract: The project falls thematically within the discipline of Civil Engineering and Transportation. It concerns research on pozzolanic additives to cement that could partially replace it, and thus reduce clinker production, while contributing to environmental protection. Clinker production is responsible for 7-8% of global CO2 emissions. Additives with pozzolanic properties that allow the structure and microstructure of hardened grouts and mortars to be shaped. Such additives can be minerals from the zeolite group, which crystal structure, the presence of zeolite water and exchange ions give this group of minerals a number of specific features, such as: adsorption properties, ion exchange capacity and  developed specific surface, which, in combination with metastability, gives them a significant pozzolanic activity. The aim of the project is to investigate the effect of the addition of zeolites (minerals with pozzolanic properties) on the process and hydration products of alite (the main mineral component of Portland cements). The following hypotheses were put forward in the project:
1. Minerals from the zeolite group with a variable Si / Al ratio in the crystal skeleton are characterized by a different level of pozzolanic properties, 2.  Determination of the mutual quantitative relations between alite and zeolite leads to the selection of optimal conditions for the hydration process,
3. The use of classical methods of phase analysis and synchrotron techniques will allow for detailed and unambiguous identification of the products of the hydration reaction of the alite-zeolite system.
To achieve the assumed goal, alite and three structural types of zeolites with different Si / Al ratios in the crystal skeleton will be obtained through laboratory synthesis. The idea and the proposed methodology are innovative and present many innovative solutions, because the authors plan to use zeolite materials with a purity of 99%, which will be obtained by converting fly ash with NaOH.
Research method used/methodology The first stage of the project will include the synthesis of materials used for research and their detailed characterization. All obtained materials will be subjected to XRD, XRF and SEM analysis in order to identify individual phases and determine the degree of purity of the products. Then, pozzolanicity tests will be performed on them, which will allow for the determination of, among others, active silica, and free CaO. For this purpose, thermal analysis methods TG / DTA and chemical methods according to ASTM C379-65 standard will be used. The slurries of the alite-zeolite system with different amounts of pozzolanic additive in the form of zeolites will be modeled. After combining the binder with water, microcalorimetric tests will be performed to assess the rate of heat release and the total heat of hydration. Conductometric tests will also be carried out to record the conductivity of the alite-zeolite system. The next stage will be the analysis of the solid - mineral products of slurries after 7, 28, 56, 90 and 180 days of maturation. For this purpose, the following research methods will be used: XRF, XRD, DTA / TG, SEM, TEM, which will be detailed through the use of synchrotron measurement techniques with the use of diffraction and microscopic methods. The obtained research results will explain the mechanism of alite hydration in the presence of minerals from the zeolite group. The impact of expected results on the development of science
The project proposed for implementation covers important issues from the discipline ""Civil Engineering and Transport"" related to the design and production of materials with strictly defined properties. The obtained research results will contribute to supplementing the missing knowledge on the influence of the addition of minerals from the zeolite group on the process and products of alite hydration. The hydration mechanism of the zeolite-alite system will be investigated and explained. Moreover, synchrotron studies will provide unique information on the structure and mineral composition of phases formed in the hydration process of alite modified with the addition of zeolites.