Adsorption properpoty of strontium ion in cementitious material hydration products from Na2O-CaO-Al2O3-SiO2-H2O system

The hydration products from Na2O-CaO- Al2O3-SiO2-H2O cementitious material system were synthesized at 35 degree C for 90 days and characterized by means of X-ray diffraction (XRD). The influence of chemical compositions of the hydration products, i.e. the atomic ratio of (Ca + Na) to (Si + Al) and Al to Si, on adsorption capacity of Sr was investigated by static adsorption method. The results show that the major hydration product is poor crystalline calcium silicate hydrate gel and a small amount of stratlingite generates in the present of Al. The adsorption capacity of the hydration products in which the atomic ratio of (Ca + Na) to (Si + Al) is 0.8 is the best in all environmental specimens. The adsorption capacity of Sr in the hydrate gel increases with the atomic ratio of Al to Si. The adsorption capacity of Sr in the hydrate gel in which the atomic ratio of (Ca + Na) to (Si + Al) and Al to Si is respectively 0.8 and 0.6 is 0.0922 mmol/g at 72 h. (authors)