Acta Geodynamica et Geomaterialia

Title: ANALYSIS OF THERMALLY-INDUCED TRANSFORMATIONS OF SILICA ROCKS AFTER HIGH TEMPERATURE HEAT TREATMENT
Authors: Geng Jishi, Sun Qiang, Zhang Yuchun and Zhang Yuliang
DOI: 10.13168/AGG.2017.0016
Journal: Acta Geodynamica et Geomaterialia, Vol. 14, No. 3 (187), Prague 2017
Full Text: PDF file (0.3 MB)
Keywords: high temperature; silica rocks; non-destructive analytical method; thermal expansion
Abstract: High temperature alters the internal microstructure of rocks and consequently changes the physical and mechanical properties of rocks. Many studies have been carried out to examine the transformations in the microstructures of rocks under high temperature through near infrared spectroscopy (NIR), Raman spectroscopy, or thermo gravimetric analysis (TGA). The current review synthesizes the data from a number of literatures and summarizes the major transformations of silica rocks under high temperature. The analysis shows that silica rocks starts to lose the water adsorbed in open pores upon heating at about 150 °C. At 200–300 °C, the reaction between SiOH (silanole) in the rocks generates new Si–O–Si bonds as well as H2O, and decreases the open pores. The rocks undergo volume expansion at >550 °C, and the volume contracts and forms new micro pores or cracks which play an important role in the evacuation of the water.