Mineral reactions in thermally treated calcareous clays for brick production

Autor(en)
Patrick Pesek, Christian Leopold Lengauer, Rainer Abart, Andreas Kurka, Gottfried Früh, Wolfgang Gaggl
Abstrakt

The commercial production of bricks usually requires firing temperatures in the range of 800-1000 °C. Some raw materials for brick production may contain up to several wt% carbonates. These carbonates thermally decompose in the range of 600-900 °C and subsequently induce the formation of new mineral phases and microporosity. This allows the production of high thermal insulating clay blocks which contribute for an energy efficient building stock, however, the additional release of CO2 is an unfavorable side effect regarding the overall carbon footprint. Strongly supporting the European Green Deal, Wienerberger AG
is striving to find solutions for a reduction of these raw material related process emissions. Therefore, an approach was targeted to find and evaluate additives, which allow lower firing temperatures in the range of decomposition temperatures of carbonates concurrently keeping the physico-technical parameters of the fired products comparable to available products. In this context, it is particularly important that the pure clay-type raw material and its thermal behavior is foremost characterized so that comparisons with clay-additive mixtures can later be made.
Test specimens were extruded, dried, and fired at 620 °C, 700 °C, 760 °C and 880 °C. The mineral phases, chemical composition and thermal behavior of the green body and the fired sherds were determined using PXRD, XRF and TA, respectively. SEM-EDX and EPMA were used for high-resolution images of microstructures and phase identification as well as for identifying mineral reactions.
The results revealed a multitude of processes occurring during the firing process of the investigated calcareous clay.

Organisation(en)
Institut für Mineralogie und Kristallographie, Department für Lithosphärenforschung
Externe Organisation(en)
Wienerberger AG
Publikationsdatum
2023
ÖFOS 2012
105116 Mineralogie, 105113 Kristallographie
Link zum Portal
https://ucrisportal.univie.ac.at/de/publications/d2aff4a8-a727-4530-9f97-b848160df98e