High temperature resistance of fly ash/GGBFS-based geopolymer mortar with load-induced damage
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ORIGINAL ARTICLE
High temperature resistance of fly ash/GGBFS-based geopolymer mortar with load-induced damage Fulin Qu . Wengui Li
. Zhong Tao . Arnaud Castel . Kejin Wang
Received: 8 January 2020 / Accepted: 29 July 2020 Ó RILEM 2020
Abstract This study investigated the effect of elevated temperatures on the residual mechanical behaviors of geopolymer mortars with initial damage induced by mechanical load. Geopolymer mortar was prepared using different fly ash/ ground granulated blast furnace slag (GGBFS) ratios and was activated by sodium silicate and sodium hydroxide solution. The physical properties and residual mechanical strength were investigated and compared with those of Portland cement mortar (PCM). After elevated temperature exposure, microstructure of GSM was studied by various microcharacterizations. The results show that before the exposure to high temperature, the addition of GGBFS increased the compressive strength of GSM, but made it more sensitive to the preloading damage, leading to the increased strength loss. After exposed to combined preloading damage and high temperature exposure, F. Qu W. Li (&) A. Castel School of Civil and Environmental Engineering, University of Technology Sydney, Sydney, NSW 2007, Australia e-mail: [email protected] Z. Tao Centre for Infrastructure Engineering, Western Sydney University, Sydney, NSW 2751, Australia K. Wang Department of Civil, Construction and Environmental Engineering, Iowa State University, Ames, IA 50011, USA
the GSM exhibited lower residual strength than the ones only suffered from preloading damage or high temperature exposure. Compared to the PCM, GSM with GGBFS performed better at temperature of 300 °C, but became worse at temperatures of 500 and 700 °C due to severe damage caused by combined high load level and large heat exposure. Finally, a low percentage of GGBFS (less than 20%) can be considered as an optimal amount for the GSM to achieve excellent fire resistance capacity. Keywords Geopolymer maoter Elevated temperature Load-induced damage Deterioration Microstructure
1 Introduction Recently, numerous studies have focused on searching for alternative low-carbon binders like geopolymers to replace Ordinary Portland cement (OPC). Geopolymers, also regarded as inorganic polymers or zeolitic precursors, are formed when an alkali solution is mixed with aluminosilicate materials made of industrial by-products including metakaolin, fly ash and ground granulated blast furnace slag (GGBFS). The use of geopolymers in practice can not only decrease the demand for OPC but also reduces carbon emissions in turn. Some previous researches have
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confirmed that geopolymers perform better than those OPC in certain performances, such as tensile strength [1, 2] acid resistance [3, 4] and impact resistance [5, 6]. In addition, some researches have also demonstrated that geopolymers have better fire resistance than OPC-based composites as the results of the different thermal e
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