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Production of autoclaved aerated concrete with silica raw materials of a higher solubility than quartz Part II: Influence of autoclaving temperature

 
: Shams, Taban; Schober, Georg; Heinz, Detlef; Seifert, Severin

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Construction & building materials : CBM 287 (2021), Art. 123072, 9 pp.
ISSN: 0950-0618
English
Journal Article
Fraunhofer IBP ()

Abstract
This study examines the effects of autoclaving temperature on the mechanical and microstructural properties of autoclaved aerated concrete (AAC) containing calcined diatomaceous earth (C-DE) as the main silica source. The autoclaving process was conducted using an autoclave at various temperatures of T = 134–192 °C and a corresponding steam pressure of P = 2–12 bar for 6 hours. The resultant phases were characterized using quantitative and qualitative X-ray diffraction (XRD), differential thermal analysis (DTA) and thermogravimetric analysis (TGA). The compressive strength of samples containing C-DE as the main silica source increased by 30% when the autoclaving temperature decreased by around 60 °C. This is in complete opposition to samples containing quartz as the only SiO2 source. The compressive strength of the latter decreased by 85% when the autoclaving temperature decreased by approximately 60 °C. For all samples, changes in compressive strength corresponded with changes in tobermorite formation.

: http://publica.fraunhofer.de/documents/N-636581.html