纳米TiO_(2)水泥砂浆在盐和冻融耦合作用下抗冻性能研究

Study on freezing resistance properties of nano-TiO_(2)cement mortar under the salt-freeze-thaw coupling effect

通过研究纳米TiO_(2)功能性作用,探究不同掺量纳米TiO_(2)水泥砂浆在5%Na_(2)SO_(4)溶液、3.5%NaCl溶液和复合溶液(2.0%Na Cl+0.35%MgCl_(2)+0.25%Na_(2)SO_(4))3种盐和冻融耦合作用下的外观形貌、质量损失率和相对动弹性模量的变化规律。试验结果表明:1%纳米Ti O_(2)掺量下的水泥砂浆在3种盐溶液中均表现出最优的抗冻性能,其抗冻能力大小为5%Na_(2)SO_(4)>复合盐>3.5%NaCl,且用于破坏性评判的关键性指标为质量损失率。扫描电镜和孔结构分析结果表明Na Cl溶液冻融循环过程造成严重损伤的原因为微膨胀Friedel′s盐的产生和有害孔和少害孔体积含量增多,无害孔的体积含量减少。

Based on the durability and combined with the functional effects of nano-TiO_(2),the changes of appearance,mass loss rate and relative dynamic elastic modulus of nano-TiO_(2)cement mortar under the coupling effect of 5%Na_(2)SO_(4)solution,3.5%NaCl solution and composite solution(2.0%NaCl+0.35%MgCl_(2)+0.25%Na_(2)SO_(4))and freezing-thawing were studied.The test results showed that the cemene mator with 1%nano-TiO_(2)showed the best freezing resistance in the three salt solutions,and its ability of freezing resistance was as follows 5%Na_(2)SO_(4)>composite salt>3.5%NaCl,and the key index used for damage evaluation was mass loss rate.Scanning electron microscopy and pore structure analysis showed that the serious damage caused by the freeze-thaw cycle of NaCl solution was caused by the production of micro-expanded Friedel′s salt,the increase of the volume content of harmful and less harmful pores and the decrease of the volume content of harmless pores.