无机盐对水泥砂浆碳化性能的影响

Effects of Inorganic Salts on the Carbonation Resistance of Cement Mortar

采用加速碳化的方法,系统研究了不同掺量下Na2SO4、NaNO2及Na2CO3三种无机盐外加剂对水泥胶砂碳化深度的影响,并用扫描电镜进行微观机理的探讨。研究表明:掺量为0.5%时,水泥胶砂的碳化深度:Na2SO4<NaNO2,掺量为1%和1.5%时,Na2SO4>NaNO2。三种掺量下,掺Na2CO3的水泥胶砂碳化最大,未掺盐的胶砂碳化最小。三种无机盐都可以改变水化环境的碱度从而加速碳化。掺Na2SO4的试件,AFt晶体尺寸随着掺量增大而减小,从而增大表面积,加速碳化。

The effects of three inorganic salts admixtures, sodium sulfate, sodium nitrite and sodium carbonate in different dosage on the carbonation resistance of cement mortar were investigated by accelerated carbonation and the microscopic mechanism are discussed by SEM. The results show that carbonation depth of mortar with NazSO4 is less than NaNO2 when the content is 0.5%. However, carbonation depth is greater than NaNO2 when the content is 1% or 1.5%. The cement mortar adding Na2CO3 showed the biggest depth in three dosages, while the cement mortar without any inorganic salt showed the smallest depth. Three admixtures can change the alkalinity of the hydration environment in order to accelerate the carbonation. The crystal size of ettringite decreased with the content of Na2SO4 increased, the surface area increased so that the carbonation resistance decreased.