Preparation And Characterization Of Mineral Polymer Precursors

Due to the complexity of raw materials,it is difficult to study the reaction mechanism of flyash-based mineral polymer materials.In order to conduct controllable research on the reaction process,it is planned to conduct“direct research”on the basis of synthetic precursors.Is ethyl silicate as silicon source,hexahydrate aluminium chloride as aluminum source,using synthetic mineral aggregate material precursor sol gel method,synthetic rate as the indicators,to analyze its synthetic process of synthetic temperature,dosage of ethanol and silica alumina ratio,water use for several main influencing factors and the influence law,combined with XRD,TG,IR and SEM test method,On the basis of structural characterization and morphology observation analysis of the synthetic precursor,the influence of controllable factors on the compressive strength of the mineral polymer prepared by the precursor system was studied,and its mechanical properties were analyzed and characterized.The main results are as follows:The optimized process parameters of precursor synthesis are as follows:When the ratio of silicon to aluminum was 10:1,the synthesis temperature was 70℃,the water consumption was n（H₂O）/（TEOS）=9,the amount of ethanol RE=n（Et OH）/（TEOS）=1,the aging time was 16h,the drying time was 48h,and the calcination at 850℃was 3h,the synthesis rate of the precursor was 81.33%.The orthogonal experiment results show that the Si/Al ratio has the most significant effect on the synthesis rate.XRD results show that the phases of the synthesized precursor are amorphous SiO₂andγ-Al₂O₃.With the reduction of silicon content in the synthetic conditions,the amorphous SiO₂content of the precursor decreases gradually,and the diffraction peak ofγ-Al₂O₃increases gradually.FTIR results showed that there was the depolymerization of Si-O and the polycondensation of Al-O,but no Formation of Si-O-Al bond.With the increase of synthesis temperature,Si-O-Si antisymmetric stretching vibration and bending vibration weaken,symmetric stretching vibration intensifies,and Si-O-Si bond polymerization intensifies.With the decrease of Si/Al ratio,the absorption peak of Si-O-Si weakens or even disappears,the vibration peak of Tetrahedral Al-O increases,and the stretching vibration of tetrahedral Al-O increases.Under the conditions of synthesis temperature 70℃,Si/Al ratio 30:1,ethanol dosage RE=1,water consumption n（H₂O）/n（TEOS）9,the synthesized precursor gel was calcined at 850℃in muff furnace for 3h,and the water-binder ratio was 0.44 and the sodium silicate modulus was 3.25.Under the condition of preparation of Na₂O·30SiO₂·Al₂O₃·10H₂O with 6mol/L sodium hydroxide solution as the raw material,curing for 1 day at 70℃and curing for 28 days at room temperature,its compressive strength is the highest,which is 51.4MPa.Figure 47;Table 8;Reference 90...