多重腐蚀环境下磷酸镁水泥基材料的硫酸盐侵蚀行为及其机理研究

硅酸盐水泥混凝土由于富含Ca(OH)2、主要水化产物C-S-H凝胶的稳定性依赖高碱氛围和呈多相多孔结构，难以满足强盐类腐蚀地区的抗硫酸盐侵蚀要求，严重影响了混凝土结构的使用寿命。磷酸镁水泥（MPC）具有快硬、高早强、环境温度适应性强、黏结性好、体积变形小、与硅酸盐水泥混凝土性能匹配、耐磨、抗冻、护筋等优点，主要水化产物MgNH4（K）PO4•6H2O在7～11的pH值范围性能稳定，结构致密程度可与陶瓷篦美。国外已有MPC基修补材料和防腐涂层专利产品问世。但有关MPC体系抗盐类腐蚀的关键技术及其机理鲜有报导。项目申请人拟通过系统研究MPC基材料在多种硫酸盐溶液长期浸泡、干湿循环、冻融循环和干湿-冻融循环交替作用下的硫酸盐侵蚀行为，分析其宏观损伤规律，揭示其硫酸盐侵蚀机理。在此基础上，提出高性能MPC基材料的设计理论和方法，并建立评价MPC基材料在多重腐蚀环境下的抗硫酸盐侵蚀能力的应用体系。

Portland cement is of rich calcium hydroxide. The stability of its main hydration product C-S-H gels depends on high alkali atmosphere. As its structure is heterogeneous and porous, Portland cement concrete is difficult to meet the requirements of sulfate erosion resistant in strong corrosive salt areas. This seriously affects the service life of concrete structure..Magnesium phosphate cement (MPC) has several advantages such as quick hardening, high early strength, good adaptability to environmental temperatures, good bonding strength, low drying shrinkage, matching performance with Portland cement concrete, abrasion resistant, good resistance to freezing and thawing, and good protection of reinforcing steel bars. Its main hydration product MgNH4（K）PO4•6H2O has stable performance of 7-11 pH and its structure is compact like ceramics. .MPC repairing material products and anticorrosion coating patent products are found overseas. Key technologies and mechanism on anti salt corrosion of MPC systems are not reported. Researches on the sulfate erosion behavior of MPC materials (long term soaking, drying and watering cycle, freezing and thawing cycle, wet-dry cycle and freeze-thaw cycle) are to be done to find macro damage law and reveal its sulfate erosion mechanism. Furthermore, design theory and evaluation method for MPC materials of high performance will be proposed.