Effect of acid attack coupled with elevated temperatures on carbonation-cured calcium sulfoaluminate and ordinary Portland cement paste

초록

This study evaluated the performance of ordinary Portland cement (OPC) and calcium sulfoaluminate (CSA) cement pastes subjected to water and carbonation curing, followed by exposure to sulfuric acid and elevated temperatures of 200 degrees C and 600 degrees C. Carbonation curing significantly enhanced the performance of CSA samples, which retained 82.90 % of their strength after acid attack, compared to only 31.73 % strength retention in OPC. Thermogravimetric analysis revealed the presence of calcium carbonate in carbonation-cured CSA samples, which decomposes at higher temperatures and thereby improves thermal resistance. Visual inspection showed that water-cured OPC samples developed a thick gypsum layer, with X-ray diffraction confirming traces of thaumasite, which masked internal damage and corrosion. In contrast, water-cured CSA samples displayed minimal visible changes, while carbonation-cured CSA samples exhibited no visible changes. After exposure to elevated temperatures, extensive cracking was observed in carbonation-cured OPC samples, whereas carbonation-cured CSA samples exhibited minimal cracking, highlighting their superior resistance to combined acid and thermal deterioration.

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