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

Different liquid accelerators including sodium aluminate liquid accelerator (SAa), fluoaluminate liquid accelerator (Fa) and aluminium sulfate liquid accelerator (ASa) were selected to investigate their influences on the carbonation properties and morphology of tricalcium aluminate (C(3)A) and tricalcium silicate (C3S) hydration products. After an accelerated carbonation test, the relative contents of ettringite (AFt), calcium hydroxide (CH) and calcium carbonate (CaCO3) in the hydration products of C(3)A and C3S samples were analysed by thermogravimetric analysis. The results indicated that the hydration products of C(3)A and C3S with liquid accelerators were easier to carbonate, and the promotion effect of SAa was the most obvious. The morphology of hydrated products of C(3)A and C3S was observed by scanning electron microscopy analysis. It was observed that different liquid accelerators had a different influence on the morphology of C(3)A and C3S hydration products. Among them, ASa had the greatest influence on the morphology of C(3)A 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.