Alternative application of wollastonite in limestone calcined Hwangtoh clay cement (LC3) systems: Engineering properties, microanalysis and resistance to sulfuric acid attack

초록

Wollastonite has high mineral reserves and great potential for use as a building material, which can promote resource utilization and sustainable development. This study aims to develop a low-carbon cementitious material with improved mechanical properties and resistance to sulfuric acid erosion by replacing limestone in limestone calcined clay cement (LC3) with wollastonite. The hydration kinetics of the mixture were analyzed, and its mechanical properties and surface resistivity were tested. The composition and microstructure of the material were analyzed at the microscopic scale via methods such as X-ray diffraction, thermogravimetric analysis, Fourier transform infrared spectroscopy, and scanning electron microscopy. The evaluation compared the surface degradation, weight loss, residual strength, and compositional changes of the mixtures after exposure to 5 % sulfuric acid for different periods. The results of hydration heat show that replacing limestone with wollastonite delays the appearance of the exothermic peak but that the cumulative heat release at 168 h does not change significantly. At a 10 % replacement level, the compressive strength and flexural strength of LC3 increased by 6.3 % and 5.1 %, respectively. When the replacement level reached 15 %, the precipitation of monocarboaluminate was inhibited, and the amount of hemicarboaluminate increased. Under sulfuric acid attack, wollastonite reduced surface degradation and spalling of LC3 while enhancing residual strength through its stability and robust microstructure.

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