摘要
Cl^(-)与SO_(4)^(2-)侵蚀是造成海洋环境下水泥混凝土劣化的主要原因,掺入辅助胶凝材料(SCMs)是改善水泥浆体抗侵蚀性能的有效方法。引入细粒度、高活性胶凝材料能加速复合水泥力学性能的发展并改善其抗蚀性,但会造成浆体流变性差、收缩应力大、开裂风险高等问题。基于Dinger-Andersen颗粒级配模型,在硅酸盐水泥基础上引入细矿渣、粗粉煤灰以及偏高岭土活性组分,设计并制备了SCMs含量高达60%的高密实度多元级配复合水泥。研究结果表明:多元级配复合水泥强度接近硅酸盐水泥,抗Cl^(-)与SO_(4)^(2-)侵蚀性能显著提升,采用快速氯离子迁移系数法(RCM)测得氯离子扩散系数降低81%,30次干湿循环硫酸盐侵蚀后耐蚀系数仍有77%。高密实度多元级配复合水泥浆体初始堆积密实、持续水化,使得孔隙显著细化,同时水化产物对氯离子固化作用强,有效阻滞有害离子向内部迁移。此外,SCMs的高效水化大量消耗Ca(OH)_(2),抑制了二次钙钒石等侵蚀产物的生成。通过颗粒级配调控与组成设计,可充分发挥胶凝材料的水化特性,显著提升浆体的密实性与抗蚀性。
Deterioration of concrete in marine environment was usually caused by chloride and sulfate attacks,and incorporating supplementary cementitious materials(SCMs)was an effective way to improve the resistance of concrete for ions attack.Although the utilization of fine cementitious materials with high hydraulic activity was beneficial to the development of mechanical properties and ions attack resistance,it would result in the poor flowability,significant internal stress,and high cracking risk of cement paste.In present study,on the basic of Dinger-Andersen particle distribution model,fine blast furnace slag and coarse fly ash were introduced into commercial Portland cement,the metakaolin was also adopted as functional component,and then the densified quadruple blended cement containing 60%SCMs was prepared.The prepared blended cement presented comparable strength with Portland cement at the early age and much higher resistance for chloride or sulfate attacks at 28 d.The RCM chloride diffusion coefficient of quadruple blended cement decreased 81%compared with Portland cement,and its index of residual strength after 30 drying-wetting cycles in sulfate solution was as high as 77%.The higher packing density and continuous hydration of quadruple blended cement paste led to significant pore size refinement and formation of products with higher chloride binding capacity,which helped block the ingress of aggressive ions from external.Moreover,more Ca(OH)_(2)was consumed due to efficient hydration of SCMs in quadruple blended cement,and the secondary ettringite formation was limited.According to the microstructural design of cement paste,the hydraulic activity of cementitious materials can be efficiently utilized,and the structural compactness of blended cement and its resistance to ions attacks can be improved subsequently.
作者
韩宇栋
郭奕群
李嘉豪
张同生
韦江雄
余其俊
HAN Yudong;GUO Yiqun;LI Jiahao;ZHANG Tongsheng;WEI Jiangxiong;YU Qijun(Central Research Institute of Building and Construction,MCC Group Co.Ltd,Beijing 100088,China;School of Materials Science and Engineering,South China University of Technology,Guangzhou 510641,China;Guangdong Low Carbon Technology Engineering Center for Building Materials,Guangzhou 510641,China;College of Civil Engineering,Hefei University of Technology,Hefei 230009,China)
出处
《材料导报》
EI
CAS
CSCD
北大核心
2023年第3期154-160,共7页
Materials Reports
基金
国家重点研发计划项目(2020YFC1909903)
国家自然科学基金(52102019,52122201)
北京市工业建筑特种材料工程技术研究中心开放基金(JZA2019Kj02)。
关键词
抗氯盐侵蚀
抗硫酸盐侵蚀
孔结构
水化产物
复合水泥
chloride resistance
sulfate resistance
pore structure
hydration product
blended cement
