外源性硫酸盐对碳硫硅钙石生成影响研究

Effect of Exogenous Sulfate on Formation of Thaumasite

研究了外源性硫酸盐种类对碳硫硅钙石生成的影响.把水泥净浆试件分别浸泡于质量分数为5%的硫酸镁、硫酸钠和硫酸铝溶液中,至设定龄期后用XRD、红外光谱和激光拉曼光谱分析侵蚀产物的矿物组成与微观结构,并测定试件强度.结果显示:经此3种硫酸盐溶液浸泡180 d后的试件均生成了碳硫硅钙石;相比硫酸钠和硫酸铝溶液,硫酸镁溶液所浸泡过试件的碳硫硅钙石衍射峰较强;随着腐蚀不断进行,各试件边角表层起皮剥落,并伴有灰白色泥状物,后期强度亦有明显降低.研究表明,对水泥净浆的碳硫硅钙石侵蚀而言,硫酸镁溶液明显比硫酸钠和硫酸铝溶液显著.

The effect of different kinds of exogenous sulfate on the formation of thaumasite in concrete is investiga- ted. The limestone powder-bearing cement pastes are immersed in MgSO,, Na2SO4 or A12 （SO4 ）3 solution （wt, 5% ） for set ages, and then the composition and microstructure of the deterioration products are analyzed by using XRD, IR spectra and laser Raman spectroscopy, the strength by ages is also measured. The results show that all three pastes generates thaumasite after 180 d, the diffraction peak intensity of the pastes immersed in MgSO, solu- tion is obviously higher than that of the pastes in Na2SO4 or A12 （SO4） 3 solution. With the development of corro- sion, the edges and surfaces of the specimens peel off, accompanied by formation of white clod, and the strength decreases evidently during the later period. It is concluded that MgSO, solution leads to thaumasite sulfate attack more seriously than A12 （SO,）3 and Na2SO＂ solution in cement pastes.