The Structure of Cementitious Materials Produced by Alkali Activation of Calcium Aluminosilicate Glasses.

A comprehensive investigation, using scanning electron microscopy, energy dispersive x-ray analysis, x-ray diffraction, and $\sp{29}$Si and $\sp{27}$Al magic angle spinning nuclear magnetic resonance spectroscopy, was conducted on the NaOH-activated blastfurnace slag system. Integration of the results from these techniques accommodated characterization of the unreacted glass, identification of the crystalline hydration products, and presentation of a proposed structure for the C-S-H phase. Crystalline hydration products identified by x-ray diffraction were CSH(I) and (C,M)$\sb4$AH$\sb{\rm x}$, and the proposed structure for the C-S-H phase consists mainly of imperfect layers of tobermorite. The structures of the hydrated phases were found to be closely related to that of the unreacted glass. Examination of the effects of time, temperature, and pH on the hydration process revealed influences on the degree of reaction only, with basically the same products formed in all samples tested. The results obtained from the NaOH-activation investigations are applicable to many alkali-activated slag systems, as manifested by the generation of similar characterizations in systems involving other hydroxides. Finally, the study was extended through the analysis of a perlite glass, the structure of which differs greatly from that of the slag, and which produces a P zeolite upon reaction in a NaOH solution. Once again, a strong relationship was discovered between the structure of the glass and the hydration products generated by alkali-activation