Title:
Linking Water Demand and Surface Area of Calcined Palygorskite
Author(s):
Valentin Roux, William Wilson, Dimitri Deneele, Michael Paris, Arezki Tagnit-Hamou
Publication:
Symposium Paper
Volume:
362
Issue:
Appears on pages(s):
302-312
Keywords:
calcined clay, palygorskite, porosity, specific surface area, water demand
DOI:
10.14359/51740891
Date:
6/6/2024
Abstract:
The effects of palygorskite-containing clays in cementitious materials are strongly dependent on the calcination temperature, which affects both reactivity and water demand. This study focuses on a palygorskite containing clay calcined at temperatures between 600 and 900°C with the aim of establishing a relationship between
the water demand of cementitious mixtures containing 20% of the calcined clay (measured with the mini-spread flow test) and the Specific Surface Area (SSA) or the porosity of the clay itself (measured by nitrogen physiosorption). Results showed a decrease of SSA with increasing temperature (especially at 800 and 900°C), as well as a linear relationship between the water demand and SSA for cementitious mixtures containing the clay calcined between 600°C and 900°C. Imaging of clays showed structural modifications with calcination: the porosity closes, and the needle-like shape of the particles disappears. Since the reactivity of the clay is the highest for a certain temperature range, it is then necessary to find a calcination temperature that both minimizes the water demand and maximizes the reactivity.