纳米SiO2对硫铝酸盐水泥基材料物理力学性能的影响

摘要

研究了不同掺量的纳米SiO2(NS)对硫铝酸盐水泥基材料力学性能和流动性的影响.结果表明:随着NS掺量的提高,新拌砂浆流动性逐渐降低.与未掺NS的砂浆相比,掺3.0%NS的砂浆在90d的抗折/抗拉强度分别提高了104.2%和90.2%,间接反映出硬化砂浆的韧性得到了改善.通过扫描电镜(SEM)、X射线衍射(XRD)和微分热重分析(DTG)揭示了强度产生机理,即NS早期的微集料填充效应、结晶成核效应以及后期微弱的火山灰效应,使得硬化浆体的微观结构更加致密,从而显著提高了硫铝酸盐水泥砂浆的强度.%The influence of different nano-SiO2 (NS) contents on mechanical properties and rheological behavior of sulfoaluminate cement (SAC) based composite materials was studied.Results show that the fluidity of fresh paste gradually decreases with the increasing of NS contents.For dosage of 3.0% NS, the flexural and tensile strengths of mortars at 90 days were increased by 104.2% and 90.2% respectively compared with that without NS, indirectly reflecting the toughness of hardened mortars is improved.The forming mechanism of strengths was revealed by scanning electron microscopy (SEM), X-ray diffraction (XRD) and derivative thermogravimetry (DTG).The micro-aggregate filling effect, nucleation effect at early age and weak pozzolanic effect at late age of NS make the microstructure more compact, which obviously enhance the strength of SAC mortars.