水泥浆体内游离态亚硝酸根含量的影响因素研究

Influencing factors of free nitrite ion content in cement paste

混凝土中游离态NO2-含量是钢筋阻锈的主要因素,本文通过测定游离态NO2-含量和水化产物的组成,评价了水泥浆体内游离态NO2-含量对钢筋的影响因素.结果表明:养护龄期越长游离态NO2-含量越低,早期游离态NO2-含量下降速率较快,后期趋于平缓,且生成NO2-AFm化合物;养护温度越高,游离态NO2-含量越低,离子固化率越高,对早期离子固化速率的影响尤为明显;水灰比越大,游离态NO2-含量越小,水泥浆试件内的游离态NO2-在养护后期仍持续固化而水灰比较小的试件在后期固化速率变慢;随着亚硝酸盐掺量的增加,水泥浆体中游离态和固化态的NO2-含量均随之增加,但固化率却随掺量的增加而减少.

The free NO2- content in concrete is the main factor of steel rust resistance.In this paper,the influence factors of free NO2- content in cement paste were evaluated by measuring the content of free NO2- and the composition of hydration products.The results showed that the longer the curing age is,the lower the free NO2- content becomes.The velocity of decay of NO2- content in the early stage is rapid and it tends to be slow in the later stage,and the NO2-AFm compounds are also formed.The higher the curing temperature is,the lower the free NO2- content becomes,the higher the ion curing rate is,and the more obvious the influence on the early ionic solidification velocity.The larger the W/C is,the smaller the free NO2- content becomes.The NO2- in cement paste is still solidified in the late stage of hydration,while the ionic solidification velocity of the specimens with relatively small W/C becomes slower.With the increasing of nitrite content,the content of NO2- in the free and solid state of the cement paste increases accordingly,but the solidification rate decreases.