AUTHOR=Huo Guang , Jiang Xinchao , Sun Xiaoheng , Li Hui , Shi Hongxing 

TITLE=Performance of high-belite calcium sulfoaluminate cement subjected to hydrochloric acid and sulfuric acid

JOURNAL=Frontiers in Materials

VOLUME=10

YEAR=2024

URL=https://www.frontiersin.org/journals/materials/articles/10.3389/fmats.2023.1282919

DOI=10.3389/fmats.2023.1282919

ISSN=2296-8016

ABSTRACT=<p>The high-belite calcium sulfoaluminate cement (HB-CSA) has displayed outstanding acid resistance. However, further research is needed to understand the mechanism behind its acid resistance fully. This study investigates the resistance of a new type of HB-CSA to hydrochloric and sulfuric acid. Additionally, the impact of the ye'elimite (C<sub>4</sub>A<sub>3</sub><inline-formula id="inf1"><mml:math id="m1" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mover accent="true"><mml:mi mathvariant="normal">S</mml:mi><mml:mo>¯</mml:mo></mml:mover></mml:mrow></mml:math></inline-formula>)-to-gypsum (C<inline-formula id="inf2"><mml:math id="m2" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mover accent="true"><mml:mi mathvariant="normal">S</mml:mi><mml:mo>¯</mml:mo></mml:mover></mml:mrow></mml:math></inline-formula>) ratio on the acid resistance of HB-CSA is discussed. The resistance performance is investigated by flexural strength and resistance index analyses, X-ray diffraction (XRD), thermogravimetric analysis (TGA), electronic computed tomography (CT) scans, and scanning electron microscopy (SEM). The results show that the HB-CSA exhibits superior resistance to sulfuric acid and hydrochloric acid compared to Portland cement. The absence of portlandite contributes to the enhanced performance of HB-CSA. In addition, as the C<sub>4</sub>A<sub>3</sub><inline-formula id="inf3"><mml:math id="m3" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mover accent="true"><mml:mi mathvariant="normal">S</mml:mi><mml:mo>¯</mml:mo></mml:mover></mml:mrow></mml:math></inline-formula>-to-C<inline-formula id="inf4"><mml:math id="m4" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mover accent="true"><mml:mi mathvariant="normal">S</mml:mi><mml:mo>¯</mml:mo></mml:mover></mml:mrow></mml:math></inline-formula> ratio decreases, the content of Aft in HB-CSA increases, leading to an increase in the acid resistance of HB-CSA.</p>