硅灰及粉煤灰对海水拌养硅酸盐水泥性能影响

Influence of silica fume and fly ash on the performance of Portland cement mixed with seawater

研究了在20℃、50℃养护温度下单掺及混掺硅灰与粉煤灰对海水拌养硅酸盐水泥性能的影响。通过测试基体抗压强度、物理性能、基体氯离子结合率及pH值,采用XRD及SEM分析基体水化产物及微观形貌。研究结果表明:硅灰对海水拌养硅酸盐水泥强度有促进作用,提高水泥基体密实度,增加化学收缩,降低水泥基体pH值,削弱Cl^(-)固化作用,改善水泥基体微观结构;粉煤灰对海水拌养硅酸盐水泥早期强度产生不利影响,但对其后期强度有促进作用,能小幅改善基体密实度,但对化学收缩、pH及Cl^(-)固化作用没有产生显著影响。粉煤灰能促进Friedel′s盐的生成,并对水泥基体微观结构产生小幅不利影响。提高养护温度能促进硅酸盐水泥抗压强度的形成,并对水泥基体微观结构有改善作用。

The influence of silica fume and fly ash on the properties of Portland cement mixed with seawater at 20℃and 50℃curing temperatures was studied.The influence of mineral admixtures on the compressive strength,physical properties,the solidification effect on chloride ions,the pH were explored.The hydration products and micro morphology of Portland cement paste were studied by XRD and SEM.The results show that silica fume can promote the strength of sea water mixed Portland cement,significantly increases the compactness and chemical shrinkage,reduces the pH value of cement matrix,weakens the effect of Cl^(-)solidification in sea water,and improves the microstructure of cement matrix.Fly ash has adverse effect on the strength of sea water mixed Portland cement in the early stage,but it improves the compressive strength in the late stage.The fly ash has much improvement on the compactness of the paste,but no significant effect on the chemical shrinkage,pH and Cl^(-) solidification.It can promote the formation of Friedel salt and slightly worsen the microstructure of cement matrix.The increase of value curing temperature can promote the formation of compressive strength of Portland cement and improve the microstructure of cement matrix.