Pozzolanic reactions of common natural zeolites with lime and parameters affecting their reactivity
The research paper investigates the pozzolanic reactions between portlandite (calcium hydroxide) and various natural zeolites, focusing on their reactivity and the factors influencing it. The study involves mixing different types of zeolites—analcime, phillipsite, chabazite, erionite, mordenite, and clinoptilolite-rich tuffs—with portlandite and water in a specific weight ratio. The pozzolanic reaction's progress is quantitatively analyzed over a period of 3 to 180 days using thermogravimetric analysis (TGA).
A comprehensive characterization of the raw materials is conducted through various methods, including quantitative X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy (SEM-EDX), and specific surface area measurements. The study finds that the reactivity of the zeolites is influenced by their Si/Al ratios, cation content, and grain size. Specifically, zeolites rich in silicon exhibit faster reactivity compared to those rich in aluminum. The external surface area affects short-term reactivity, while the Si/Al ratio is more significant for long-term reactivity.
The research paper also discusses the mechanisms of pozzolanic activity, noting that the early reactivity is primarily influenced by the external surface area and cation content, while long-term reactivity is more closely related to the Si/Al ratio. The findings contribute to a better understanding of the pozzolanic activity of natural zeolites, which are recognized for their potential benefits in enhancing the properties of concrete, such as durability and resistance to chemical attacks.
This research paper is significant in the field of civil engineering and materials science, particularly in the context of sustainable construction practices. The use of natural pozzolans like zeolites can improve the performance of concrete while reducing the environmental impact associated with traditional cement production. By elucidating the factors that affect the reactivity of zeolites, the study contributes to ongoing discussions about optimizing the use of alternative materials in concrete formulations. The insights gained from this research can guide engineers and material scientists in selecting appropriate pozzolans to enhance concrete properties, ultimately leading to more durable and sustainable construction practices.
