The phase composition study of hydraulic binder prepared from calcined clay, anhydrite and lime

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Klára Pulcová*, Martina Šídlová, Martina Kohoutková, Rostislav Šulc, František Škvára

Nowadays, when the emphasis is on ecology and reduction of CO2 emissions, the preparation of a new hydraulic binder that could at least partially replace the high-emission Portland cement is becoming a topical issue. This work deals with phase composition study of the new hydraulic binder created from metakaolin calcined clay, anhydrite II and lime. A number of pastes with varying composition were prepared. After raw material characterization, the phase composition was measured using X-ray diffraction with evaluation after 28 and 180 days. It was found that after 28 days the main crystalline binder phase was ettringite, further, the samples contained high proportion of amorphous phase and smaller amount of anhydrite, portlandite, calcite and quartz. After 180 days, two new phases stratlingite and gypsum were detected in percent units. Nevertheless, it was clear that the sulfocalcic binder is stable from the point of view of the phase composition in the monitored time of 180 days, and with an optimal composition it reaches a compressive strength of up to 80 MPa.

Keywords: Hydraulic binder; calcined clay; metakaolin; X-ray diffraction; ettringite

Proscience vol. 9

Pp 45-50

DOI: 10.14644/EC2023.008