单掺活性MgO水泥膨胀性能与微观结构表征  

Expansion Properties and Microstructure Characterization of Cement Paste Mixed with Reactive MgO

作　　者：朱静[1] 叶楠[1] 杨家宽[1] 

机构地区：[1]华中科技大学环境科学与工程学院,武汉430074

出　　处：《武汉理工大学学报》2013年第8期14-18,38,共6页Journal of Wuhan University of Technology

基　　金：教育部新世纪人才支持计划(NCET-09-0392);华中科技大学博士创新基金(0109261946)

摘　　要：胶凝材料水化反应过程中收缩或膨胀体积变化是由其水化产物性质决定。水泥的收缩值随水化龄期的变化规律反应了水泥水化特点。研究活性MgO水泥浆体水化过程及水化产物,探索单掺MgO对水泥体系膨胀特性的影响。活性MgO由菱镁矿经700℃保温2.5h煅烧制备。单掺8%活性MgO水泥净浆的安定性合格,单掺质量分数12%活性MgO水泥净浆的安定性不合格。MgO掺量由4%增长到20%时,20℃水浸泡膨胀率由1.88‰增加到10.05‰。纯水泥浆体20℃水浸泡90d后的孔容为0.018cm3/g,活性MgO增大了水泥浆体的孔容。MgO质量掺量由8%增加至12%时,水化产物Mg(OH)2堵塞了孔径,浆体20℃水浸泡90d的孔容从0.079cm3/g减小到0.030cm3/g。12%MgO水泥浆体孔径分布范围比8%MgO水泥浆体广,主要分布在2～100nm之间,且孔径微分分布增大。根据MgO水化反应产物、形貌表征以及孔径分析、体积膨胀率的实验结果,解释单掺活性MgO导致水泥浆体安定性问题的原因。Shrinkage or expansion properties of cementitious material during the hydration are determined by the nature of the hydration products. Variations of shrinkage during the curing ages reflect the cement hydration reaction characteris- tics. The properties of hydration products and the expansion ratio of MgO cement, reactive MgO mixed with OPC paste in the hydration process are studied. Reactive MgO was prepared by magnesite calcined at 700 ℃ for 2. 5 h. The soundness of cement paste mixed with 8% reactive MgO was stability, for cement paste with 12% reactive MgO was instability. In- crease the addition of MgO from 4% to 20%, expansion ratio increased from 1.88 %0 to 10. 05 %0 in 20 ℃ water. The pore volume of pure cement paste for 90 d in 20 ℃ water is 0. 018 cm3/g,and reactive MgO increases the pore volume of ce- ment paste. Increase the addition of MgO from 8% to 12% ,the pore volume of the paste for 90 d in 20 ℃ water reduced from 0. 079 cm3/g to 0. 030 cm3/g for blocking the aperture by hydration product Mg（OH）2. Pore size distribution range of 12% MgO cement paste was mainly between 2-100 nm. It is wider than that of 8% MgO cement paste,and the pore size differential distribution increases. According to the results of hydration reaction products, morphology characteriza- tion, pore analysis and expansion ratio, stability problems of cement paste caused by reactive MgO can be well explained.

关 键 词：活性MgO 膨胀水泥 形貌表征 孔径分析 

分 类 号：TQ172.12[化学工程—水泥工业]