In order to investigate the influence of three key molar ratios (n(SiO2)/n(Al2O3),n(K2O)/n(Al2O3) and n(H2O)/n(K2O)),a total of nine potassium poly-sialate-disiloxo (K-PSDS) geopolymeric cement matrices were designed according to orthogonal design principle. Subsequently,XRD,ESEM-EDXA and MAS-NMR techniques were employed to further characterize the microstructure of the most fully reacted geopolymeric cement matrix. The experimental results show that n(K2O)/n(Al2O3) has the most significant effect on compressive strength amongst the three ratios. The highest compressive strength (20.1 MPa) can be achieved when n(SiO2)/n(Al2O3)=6.5,n(K2O)/n(Al2O3)=0.8 and n(H2O)/n(K2O)=10.0. The FTIR spectra of nine PSDS geopolymeric cement matrices also indicate that geopolymeric cement matrix with the highest strength is the most fully reacted one and possesses the largest amount of geopolymeric cement products. The microscopic analysis reveals that PSDS geopolymeric cement matrix possesses structural characteristics similar to gel substances in having a wide range of Si endowments,but predominantly the framework molecular chains of Si partially replaced by 4-coordinated Al tetrahedral.
