Effects of liquid accelerators on carbonation properties of C3A and C3S hydration products

Abstract

Different liquid accelerators including Sodium Aluminate liquid accelerator (SAa), Fluoaluminate liquid accelerator (Fa) and Aluminum Sulfate liquid accelerator (ASa) were selected to investigate their influences on the carbonation properties and morphology of C₃A and C₃S hydration products. After accelerated carbonation test, the relative contents of ettringite (AFt), calcium hydroxide (CH) and calcium carbonate (CaCO₃) in the hydration products of C₃A and C₃S samples were analyzed by thermogravimetric analysis (TG). The results indicated that the hydration products of C₃A and C₃S with liquid accelerators were easier to be carbonated, and the promotion effect of SAa was the most obvious. The morphology of hydrated products of C₃A and C₃S was observed by scanning electron microscopy analysis (SEM). It was observed that different liquid accelerators had different influence on the morphology of C₃A and C₃S hydration products. Among them, ASa had the greatest influence on the morphology of C₃A and C₃S hydration products, and experiments proved that ASa could promote the transformation of AFt into AFm and make the CH crystal structure become thicker and larger.