偏高岭土-矿渣地聚物孔结构及介质传输性能研究

Pore Structure and Media Transport Properties of Metakaolin-Slag Geopolymer

地聚物是通过化学激发生成的具有低碳属性的新型胶凝材料,具有部分取代水泥的巨大潜力。本文通过压汞试验表征了偏高岭土-矿渣地聚物净浆及砂浆的孔隙结构,分析了液固比、砂体积分数等因素对孔结构特性的影响,明确了孔结构特性与面分形维数的相关性。采用氯离子非稳态电迁移试验、非稳态自然扩散试验和水分扩散试验,研究了偏高岭土-矿渣地聚物净浆与砂浆的抗渗透性能,分析了液固比、砂体积分数及孔面分形维数与浆体介质传输性能的相关性。结果表明:随着液固比增大,地聚物净浆的孔隙率和最可几孔径均增大,抗渗透性能降低;地聚物砂浆的抗渗透性能优于水泥砂浆,砂体积分数增加时,地聚物砂浆的最可几孔径和介质传输系数均先减小后增大,抗渗透性能先增强后减弱;孔面分形维数能较好地表征地聚物浆体孔结构特性,并与抗渗透性能相关性良好。

Geopolymer is a novel cementitious material with low carbon properties produced by chemical activation,which has great potential to partially replace cement.The pore structure of metakaolin-slag geopolymer paste and mortar was characterized by mercury intrusion porosimetry tests.The effects of liquid-solid ratio and sand volume fraction on pore structure properties were analyzed,the correlation between pore structure properties and surface fractal dimension was clarified,and the permeability resistance of metakaolin-slag geopolymer paste and mortar was investigated using chloride unsteady electromigration test,unsteady natural diffusion test and moisture diffusion test.The correlation between liquid-solid ratio,sand volume fraction,pore surface fractal dimension,and slurry media transport performance was analyzed.The results show that with the increase of liquid-solid ratio,the porosity and the most available pore size of geopolymer paste increase and the permeability resistance decreases.The permeability resistance of geopolymer mortar is superior to that of cement mortar.The most available pore size and media transfer coefficient of geopolymer mortar decrease first and then increase with the increase of sand volume fraction,and the permeability resistance increases first and then decreases.Furthermore,the pore surface fractal dimension can well characterize the pore structure properties of geopolymer slurry and has a good correlation with permeability resistance.