片麻岩石粉、硅灰对混凝土抗冻性能的影响研究

Study on influence of gneiss stone powder and silica fume on freezing resistance of concrete

为研究片麻岩石粉和硅灰对混凝土抗冻性能的影响,通过对冻融循环前后掺加片麻岩石粉和硅灰的混凝土进行动弹性模量试验、单轴压缩试验及SEM观测,分析了片麻岩石粉和硅灰对混凝土的抗冻性能和微观结构的影响规律,采用最小二乘法建立冻融损伤模型。试验结果表明:片麻岩石粉掺量为10%时可以小幅度提升混凝土的抗冻性能,但随着片麻岩石粉掺量增加,混凝土的抗冻性能迅速降低;混凝土的抗冻性能随着硅灰掺量增加而逐步提升,但当硅灰掺量超过8%时,硅灰对改善混凝土抗冻性能的能力降低。电镜扫描结果表明,片麻岩石粉和硅灰可以优化混凝土内部结构,提高界面过渡区粘结强度。通过数据拟合得到的冻融损伤模型精度较高,可以反映片麻岩石粉和硅灰对混凝土冻融损伤的影响。

To study the influence of gneiss stone powder and silica fume on the freezing resistance of concrete,through the dynamic elastic modulus test,uniaxial compression test and SEM observation of concrete mixed with gneiss stone powder and silica fume before and after the freeze-thaw cycle,the influence of gneiss stone powder and silica fume on the freezing resistance and microstructure of concrete was analyzed,and the freeze-thaw damage model was established using the least square method.The test results show that the freezing resistance of concrete can be improved slightly when the gneiss stone powder content is 10%,but the freezing resistance of concrete decreases rapidly with the increase of gneiss stone powder content;the freezing resistance of concrete increases gradually with the increase of silica fume content,but when the silica fume content exceeds 8%,the ability of improving the freezing resistance of concrete decreases.The scanning results of electron microscope show that gneiss stone powder and silica fume can optimize the internal structure of concrete and improve the bonding strength of interfacial transition zone.The accuracy of the freeze-thaw damage model obtained by data fitting is high,which can reflect the influence of gneiss stone powder and silica fume on the freeze-thaw damage of concrete.