低湿度半浸泡环境下粉煤灰对砂浆试件硫酸盐侵蚀性能的影响  

Effect of Fly Ash on Performance of Mortars Partially Exposed to Sulfate Solution Under Low Humidity

作　　者：孙道胜 王辉 刘开伟 王爱国 李萍 张高展 管艳梅 SUN Daosheng;WANG Hui;LIU Kaiwei;WANG Aiguo;LI Ping;ZHANG Gaozhan;GUAN Yanmei(Anhui Key Laboratory of Advanced Building Materials,Hefei 230601,China;School of Materials and Chemical Engineering,Anhui Jianzhu University,Hefei 230601,China)

机构地区：[1]安徽省先进建筑材料重点实验室,合肥230601 [2]安徽建筑大学材料与化学工程学院,合肥230601

出　　处：《材料导报》2020年第14期14079-14086,共8页Materials Reports

基　　金：国家自然科学基金(51578004,51608004,51778003);安徽省教育厅自然科学基金(KJ2018JD18);安徽建筑大学博士启动基金(2018QD49)。

摘　　要：在T=(20±3)℃、相对湿度RH=(35±5)%的低湿度环境下,将粉煤灰掺量为0%、15%、30%和45%的水泥砂浆半浸泡在5%(质量分数)Na 2SO 4溶液中进行180 d侵蚀实验。研究侵蚀前后砂浆的孔结构、毛细吸附传输特性、砂浆试件盐结晶区的SO 42-浓度以及侵蚀剥落体积与质量变化,并采用XRD、SEM等手段对侵蚀产物和微观结构进行表征。研究结果表明:提高粉煤灰掺量会增加砂浆毛细孔占比,导致其在水中以及硫酸钠溶液中的毛细吸附传输特性明显加强,提高了砂浆试件盐结晶区硫酸根离子的浓度。未掺粉煤灰的PO组被侵蚀180 d后,砂浆试件盐结晶破坏区侵蚀产物除了有硫酸钠外,还形成了较多的石膏相,引起砂浆试件盐结晶区破坏的主要原因是化学侵蚀。掺有粉煤灰组分的砂浆试件盐结晶区侵蚀产物有较多的硫酸钠,未明显观察到石膏。且随着粉煤灰掺量的增加砂浆试件侵蚀破坏越严重,表现为更加严重的物理型盐结晶造成的侵蚀破坏,导致砂浆试件质量损失增多。这表明砂浆试件随粉煤灰掺量的增加可进一步细化孔隙,在低湿度环境下,更有利于硫酸盐溶液的毛细吸附传输速率的增加,引起更严重的物理型盐结晶侵蚀破坏。Cement mortars containing 0%,15%,30%,and 45%of fly ash were partially immersed in 5wt%Na 2SO 4 solution for 180d corrosion experiments in T=(20±3)℃,RH=(35±5)%of relative low humidity environment.The pore structure,capillary sorptivity transportation characteristics,SO 42-concentration and volume-loss and mass-loss of the mortars before and after erosion were analyzed,the erosion products were characterized by XRD and SEM.The results show that with the increase of fly ash content for mortars increase the proportion of capillary pores,results in a significant increase in capillary sorptivity transmission characteristics and causes higher SO 42-concentration in crystallization zone.The sample without fly ash PO sample,after erosion for 180 days,except for sodium sulfate,the erosion products in the salt crystallization zone of the mortar specimen form more gypsum phase,the main reason for the destruction of the salt crystallization zone of the mortars is chemical erosion.While the sample addition with fly ash samples,the products of salt crystallization zone of sample has only sodium sulfate,and no gypsum obviously.And with the increase of the amount of fly ash,the damage of the mortar specimen is more serious,and shows as more severe physical salt attack,results in much more serious mass-loss of the mortar specimen.It indicates that the mortars with the increase of the amount of fly ash specimen can refine the pores.In the low humidity environment,it will increase the capillary sorptivity transmission rate of the sulfate solution and caused more serious physical salt crystal damage.

关 键 词：低湿度 半浸泡 硫酸盐侵蚀 粉煤灰 侵蚀机理 物理盐结晶 

分 类 号：TU528[建筑科学—建筑技术科学]