纳米SiO_2与粉煤灰协同改性水泥基材料性能研究

Synergistic Effect of Nano Silica and Fly Ash on the Cement-based Materials

通过调整纳米SiO_2与粉煤灰的比例,研究了两者协同作用对水泥基材料性能的影响。结果表明,纳米SiO_2(NS)和粉煤灰协同作用效果优于NS单一掺加,3%(质量分数,下同)纳米SiO_2和不大于30%的粉煤灰同时掺加可以补偿粉煤灰引起的早期强度降低,且砂浆28d抗压强度不降低。随着NS掺量增加水泥基材料的干燥收缩增大,粉煤灰可以改善纳米SiO_2对干燥收缩的不利影响。随着NS掺量的增加,试件的抗冻性和抗氯离子渗透性能均得到提升,掺加3%NS与30%粉煤灰使水泥基材料达到最佳耐久性能。NS可以缩短水泥水化诱导期,加速水泥水化进程,且使胶凝体系总放热量增加。在水泥粉煤灰体系中掺入NS后,非蒸发水含量在早期明显增多,但在后期增长缓慢。

The synergistic effect of nano silica and fly ash on cement based materials was studied by adjusting the ratio of nano SiO 2 and fly ash.The results showed that the effect of nano silica and fly ash on cement is better than that of adding single nano silica.The early compressive strength reduction by fly ash can be compensated by adding 3%nano silica and less than 30%fly ash into mortar without the decrement of 28 days compressive strength.The drying shrinkage of mortar increased with the increase of nano SiO 2,but the fly ash can relieve the drying shrinkage of nano SiO 2.With the increase of nano silica,the freeze thaw resistance and chloride corrosion resistance of the specimens were improved,and 3%nanometer silica and 30%fly ash could further enhance the durability of cement-based materials.Nano SiO 2 can shorten the induction period of cement hydration and accelerated the process of cement hydration,and the total heat release was increased when nano SiO 2 was added.When adding nano SiO 2 into the cement-fly ash system,the content of non evaporated water was increased obviously in the early stage,but the increment of the non evaporated water in the late stage was slow.The synergistic effect of nanosilica and fly ash improves the performance of cement mortar,which is beneficial to the performance complementarity.