GRC制品抗泛碱性能的提升及机理

Improvement of Anti-efflorescence Property of GRC Products and Its Mechanism

玻璃纤维增强水泥(GRC)制品因其自重轻、安装易、强度高、可预制等诸多优点,成为装饰水泥基材料中应用最为广泛的产品之一。制约其使用的一个重要因素是在降水过后水分蒸发等干湿循环服役环境下,GRC制品表面会析出白霜,即发生泛碱现象。目前解决水泥基材料泛碱问题的主要方法包括掺入超细集料、表面疏水处理等,没有从材料根本上解决泛碱问题。本工作使用基于微生物矿化技术的微生物抗泛碱剂提升GRC制品的抗泛碱性能,将GRC制品内部的钙离子固定,避免其随水分迁移至表面并生成泛碱物质。试验结果表明,掺加微生物抗泛碱剂时,GRC制品的泛碱面积率可显著降低至3%左右。同时探究了耐碱玻璃纤维对GRC制品抗泛碱性能的影响。X-CT和MIP测试结果表明,二者对GRC制品抗泛碱性能的影响机理均与孔结构有关。此外,本工作改进了水泥基材料抗泛碱性能的测试方法并提出了新的定量评价指标,即泛碱均匀度。

Glass-fiber reinforced cement(GRC)products are one of the most widely used cement-based decorative materials on account of low weight,easy installation,high strength,and capability of being precast.An important factor restricting the use of GRC products is the white substances separated on the surface when serving in a drying-wetting cycle circumstance,that is efflorescence.The main methods to solve the problem of efflorescence include adding superfine aggregate,surface superhydrophobic treatment,and so on.These methods do not fundamentally solve the problem from the material.In this work,the microbial anti-efflorescence agent was used to improve the anti-efflorescence property of GRC products,which was based on bio-mineralization technology.The microbial anti-efflorescence agent can fix the Ca 2+inside the products,thus preventing it from moving to the surface with water and leading to efflorescence.The results showed that the efflorescence area ratio could significantly decrease to around 3%with the agent.The effects of glass-fiber on the anti-efflorescence property of GRC were also studied.X-CT and MIP tests showed that the effects of both microbial anti-efflorescence agent and glass-fiber on the anti-efflorescence property of GRC were related to the change of pore structure.Besides,the measuring method of the anti-efflorescence property was modified,and a new indicator,efflorescence uniformity,was proposed in this work.