粉煤灰-矿渣基地聚物胶凝材料的力学性能及其微观结构试验研究

文章研究了粉煤灰与矿渣的质量比、碱激发剂的质量分数和碱激发剂模数对地聚物胶凝材料的水化反应、凝结时间及力学性能的影响，并通过扫描电子显微镜(scanning electron microscope, SEM)、X-射线能谱仪(energy dispersive X-ray spectroscopy, EDS)、傅里叶变换红外光谱仪(Fourier transform infrared spectroscopy, FTIR)等对材料微观结构进行了表征。结果表明：随着粉煤灰与矿渣质量比的不断减小，地聚物胶凝材料的水化反应速率加快，凝结时间缩短，抗压强度和抗折强度不断增大；随着碱激发剂质量分数的增加，地聚物胶凝材料的水化反应速率加快，凝结时间缩短，抗压强度增大，抗折强度先增大后减小；随着碱激发剂模数的增加，地聚物胶凝材料的水化反应速率减慢，凝结时间延长，且抗压强度和抗折强度均不断减小。分析试验结果发现，在粉煤灰与矿渣的质量比为$2:8$ 、氧化钠和二氧化硅的质量分数分别为 $5.25\%$ 和 $4.20\%$ 时， $28\mathrm{d}$ 地聚物胶凝材料的抗压强度和抗折强度分别达到 $68.90, 11.50 \mathrm{MPa}$ 。微观测试结果进一步证明，随着粉煤灰与矿渣质量比的减小、碱激发剂质量分数的增加和碱激发剂模数的减小，SEM表征的微观结构逐渐趋向致密，与宏观力学性能的变化是一致的。同时EDS和FTIR表征结果表明，C-A-S-H凝胶是不同配比地聚物水化产物的主要成分。该研究结果为地聚物胶凝材料的推广和应用提供了理论基础。

In this paper, the effects of the ratio of fly ash to powder, the mass fraction of alkali activator and the modulus of alkali activator on the hydration reaction, setting time and mechanical properties of the geopolymer material were studied. The microstructure of the material was characterized by scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS) and Fourier transform infrared spectroscopy (FTIR). The results show that with the decrease of the ratio of fly ash to powder, the hydration reaction rate of the geopolymer material is accelerated, the setting time is shortened, and the compressive strength and flexural strength are increased. With the increase of the mass fraction of alkali activator, the hydration reaction rate of the geopolymer material is accelerated, the setting time is shortened, the compressive strength is increased, and the flexural strength is first increased and then decreased. With the increase of the modulus of alkali activator, the hydration reaction rate of the geopolymer material slows down, the setting time prolongates, and the compressive strength and flexural strength decrease continuously. The results show that when the ratio of fly ash to powder is $2:8$ and the mass fractions of sodium oxide and silicon oxide are $5.25\%$ and $4.20\%$ , respectively, the compressive strength and flexural strength of the 28-day geopolymer material reach $68.90 \mathrm{MPa}$ and $11.50 \mathrm{MPa}$ . The microscopic test results further prove that with the decrease of the ratio of fly ash to powder, the increase of the mass fraction of alkali activator and the reduction of the modulus of alkali activator, the microstructure revealed by SEM gradually tends to be dense, which is consistent with the change of macroscopic mechanical properties. The results of EDS and FTIR show that C-A-S-H gel is the main component of the hydration products of different ratios of geopolymer material. The conclusion of the study provides a theoretical basis for the popularization and application of geopolymer material.