高胶凝性富铁磷铝酸钡钙水泥熟料矿相体系的合成及水化硬化机制研究

In addition to high early strength and fast hardening performance, phosphoaluminate cement with main mineral of calcium phosphoaluminate has properties of excellent corrosion resistance and good durability. Whereas, many important special engineering (such as military, offshore, island, tunnel etc.), puts forward higher request to this type of cement at the aspects of mechanical strength and its later strength development, hydration and hardening controllability, durability under the periodic environment of high temperature, high humidity and high sodium. So the research and development of new type of phosphoaluminate cement becomes more urgent. Project applicant found that calcium barium phosphoaluminate cement mineral has outstanding early and long term strength, and its setting time is conveniently controlled. Also, iron-rich sintering condition is benefit to its synthesis, and associated C4AF with structure of iron and alumina network can improve the durability of cement. Based on this, this research will investigate single crystal synthesis, form mechanism and kinetics of calcium barium phosphoaluminate mineral, then break through the bottle neck of low temperature synthesis by means of element doping and mineralization for sulphur and boron. Using minerals composite technology, the research will solve the minerals coexistence and compatibility problem of calcium barium phosphoaluminate, calcium phosphate, calcium aluminate and C4AF. The three kinds of minerals components will be optimized and the new type of high cementitious iron-rich calcium barium phosphoaluminate cement clinker mineral system will be established. At last, the hydration process of this new type of cement clinker system will be studied, and then its hydration and hardening mechanism will be explored deeply. This will lay the theoretical foundation for the new type of cement clinker system in the application of special engineering and construction.

以磷铝酸钙为主导矿物的快硬早强磷铝酸盐水泥具有良好抗蚀和耐久性，已开始应用于工程建设。但许多重要特殊建设工程，如军事、海洋、岛礁、隧道等，对该水泥强度及后期增长率，水化硬化速度的可控性，高温、高湿、高盐等周期性环境作用下的耐久性等方面提出更高要求，对研发新型磷铝酸盐水泥需求迫切。申请人发现，Ba2+引入磷铝酸钙形成的磷铝酸钡钙矿相具有优异的早期和长期力学性能，凝结时间可控；富铁煅烧利于其合成，且伴生的C4AF因具铁铝网络结构可大幅提升水泥耐久性。基于此，本研究拟通过对富铁煅烧条件下磷铝酸钡钙单矿合成、形成机制和动力学研究，并结合S、B元素掺杂和矿化技术，突破其低温合成瓶颈；利用矿相复合技术，解决磷铝酸钡钙、磷酸钙、铝酸钙及C4AF共存和相容性问题，并优化匹配矿相组成，建立新型富铁磷铝酸钡钙水泥熟料矿相体系；探索该矿相体系水化硬化过程，揭示其水化硬化机制，为在特殊建设工程应用提供理论指导。

军事、海洋、岛礁、隧道等特殊建设工程处在严酷环境中服役，其建设需要高强度和高耐久的新型胶凝材料。本项目从磷铝酸钡钙单矿制备、形成机制和动力学研究入手；结合元素掺杂和矿化技术，解决了磷铝酸钡钙、磷酸钙、铝酸钙等矿相共存和相容性问题；矿相匹配后建立了高胶凝性磷铝酸钡钙水泥熟料体系；进而探索该矿相体系水化硬化过程，揭示其水化硬化机制，这些研究丰富了特种胶凝材料品种。研究结论如下：.煅烧温度在750-1100℃时，原料开始分解，并且有铝酸盐过渡相出现，例如BaAl2O4，BaCa2Al8O15和BaCa2Al8O15；在1200-1400℃区间内，仍然存在大量的铝酸盐过渡相，并且出现关键磷酸钡钙盐过渡相（Ba3Ca3(PO4)4），磷酸钡钙盐（Ba3Ca3(PO4)4）；磷铝酸钡钙（Ca6.4Ba1.6Al12P2O31）在1500℃时初步形成，在1540℃时，磷铝酸钡钙大量形成。磷铝酸钡钙是由BaCa2Al8O15、CaAl2O4、Ca3(PO4)2、Ca2P2O7和Ca4O(PO4)2五种矿物之间反应组合生成的。或者由BaCa2Al8O15、CaAl2O4、Ca3(PO4)2、Ca2P2O7和Ba2Ca(PO4)2五种矿物之间反应组合生成的。在1500-1530℃和1540℃-1560℃两个温度区间的Ca6.56Ba1.44Al12P2O31反应机制不同，分别符合Jander方程和Ginstling方程，这两个温度区间的矿物形成的反应活化能分别为1310KJ/mol-1和324KJ/ mol-1。高强型磷铝酸钡钙水泥生料配料三率值为铝磷比为1.42，铝铁比为1.92，碱度系数为0.90，且BaO取9.0%和Fe2O3取6.35。当煅烧温度为1420℃时，磷铝酸钡钙水泥熟料的主要矿相包括C6.4B1.6A6P、CaAl2O4、Ca3(PO4)2和C4AF；硬化水泥浆体1d、3d、7d、14d和28d抗压强度分别为84.5、106.0、125.1、138.0和172.0 MPa；矿化剂中硫铁组合和硫铜组合均可显著降低熟料煅烧温度，少量MgO和铁组合有利于水泥熟料的低温煅烧。磷铝酸钡钙水泥硬化水泥浆体结构致密，水化产物主要为C(A,P)H10和铝胶，并包含少量的C2(A,P)H8，且安定性合格。初凝和终凝为分别为240min和260min，工程应用需添加适宜促凝剂。