硫酸铵环境下超细矿渣粉掺量对水泥砂浆性能的影响

摘要

采用压汞法(MIP)、乙二胺四乙酸(EDTA)化学滴定法及X线衍射(XRD)等检测手段研究掺超细矿渣粉的水泥砂浆在5%(NH4)2 SO4溶液中浸泡2 a后的物理和化学变化.结果表明:通过显色反应可以清晰地观察到水泥砂浆中(NH4)2 SO4的扩散边界,并发现随着超细矿渣粉掺量的增加,水泥砂浆试块中(NH4)2 SO4扩散深度减小,而试块强度增加.通过MIP检测出掺加超细矿渣粉后的水泥砂浆的腐蚀区域的孔隙率明显小于未掺加超细矿渣粉的水泥砂浆.通过化学分析测定了游离Ca2+和SO3含量,两者含量均随水泥砂浆的深度增加而逐渐降低,并随超细矿渣粉含量的增加而减小.因此,添加超细矿渣粉能有效阻滞(NH4)2 SO4的侵蚀.%Physical and chemical changes of cement mortar blended with ultrafine slag powder immersed in 5% ( NH4 ) 2 SO4 solutions for 2 years were investigated by means of mercury intrusion porosimetry ( MIP ) , elhylene cliamine tetraacetic acid ( EDTA ) chemical titration and X-ray diffraction ( XRD ) . Results showed that diffusion boundary of ( NH4 ) 2 SO4 into mortars could be clearly observed by colorization of barium rhodizonate and the diffusion depths of ( NH4 ) 2 SO4 into mortars decreased with the increasing of ultrafine slag powder content addition. The addition of ultrafine slag powder also notably reduced the strength of mortars immersed in (NH4)2SO4 solutions. Porosity of mortars within (NH4)2SO4 diffusion region decreased with the addition of ultrafine slag based on MIP determination.Concentrations of Ca2+ and SO42-were determinded by chemical analysis,and they all decreased along with the increasing of diffusion depth and also with the addition of ultrafine slag powder. It is believed that the addition of ultrafine slag powder into cement mortar could effectively improve the resistance performance against ( NH4 ) 2 SO4 attack.