硫铝酸钡（锶）钙特种水泥基海工修补材料胶凝膨胀机理研究

Poor application environment of marine concrete lead to serious erosion damage and the enormous maintenance cost, and the repair methods are finite; therefore the high efficiency and low cost cement-based repair materials need to be manufactured. Because the barium (strontium)-calcium sulphoaluminate cement has excellent properties of penetration resistance, fast setting and high strength, the expansion coefficient and setting time are controllable, so it become an ideal base material for marine concrete repair, however, the mechanism of hydration and expansion of cement are not clear enough.In addition, owing to the different damage conditions of marine concrete engineering，such as micro crack, macro crack, denudation, falling off, the repair materials need to have special cementation and expansion properties. This project will synthesise a series of minerals of barium (strontium) calcium suphoaluminate firstly, and then research on the firing technology, maximum mole content of barium (strontium) in the minerals,the crystal structure parameters, strength changing law, the properties of resistance to seawater corrosion, and the mechanism of hydration and expansion. On the basis of single mineral research, to confirm the clinker mineral composition and proportion, to sinter a series cement clinker and optimize the relationship between cement clinker and gypsum. The type and proportion of auxiliary cementitious materials and the fineness of barium (strontium) calcium suphoaluminate cement will be optimized and its durability will be tested. The hydrated strength and expansion models will be built based on the theoretical calculation and the measured results. To provide theoretical support for the cement based repairing material under different destruction of marine concrete engineering structure.

海工混凝土应用环境恶劣、侵蚀损坏严重、维护投入巨大、修补方法有限，亟待高效低成本的水泥基修补材料。由于硫铝酸钡(锶)钙水泥的防腐抗渗、快硬高强性能优异，且膨胀系数和凝结时间可调，使其成为理想的海工修补基础材料，但是其水化胶凝膨胀机理研究尚不系统深入。针对海工混凝土工程出现的微裂纹、裂缝、剥蚀、脱落等不同损坏情况，需要修补材料具有不同的胶凝膨胀特性。本课题将合成系列硫铝酸钡(锶)钙单矿物，研究其烧成制度、确定钡(锶)的最高摩尔比例、晶体结构参数、强度变化规律、抗海水侵蚀性能、水化硬化及膨胀机理；在单矿物研究基础上，确定硫铝酸钡(锶)钙水泥熟料的矿相组成设计，烧制系列水泥熟料并优化与石膏的匹配关系；调整水泥细度，辅助胶凝材料的种类和比例，检验其耐久性及胶凝膨胀特性；结合强度及膨胀系数的理论计算与实测结果对比，建立单矿物及修补材料的水化胶凝膨胀模型；为适应不同修补条件的海工修补材料提供理论依据。

硫铝酸盐水泥因具有快硬早强、可调节膨胀、硬化浆体致密性高等特性，在水工工程的建设与修补加固等领域发挥着巨大的作用。硫铝酸钙(C4A3$)是硫铝酸盐水泥中的主要成分，采用Ba2+或Sr2+取代C4A3$中的Ca2+可以合成硫铝酸钡钙矿物（C4-xBxA3$）和硫铝酸锶钙(C4-xŠxA3$)，从而烧成性能更为优异的硫铝酸钡（锶）钙水泥，并且可以利用钡（锶）化工废渣减轻环保压力。.在C4-xBxA3$和C4-xŠxA3$晶体结构的研究方面，随着Sr2+取代量的增大，C4-xŠxA3$系列物相由正交晶系向立方晶系转变，锶的取代不影响C4-xŠxA3$官能团的种类。C4-xŠxA3$中Sr2+定向取代C4A3$中的Ca2+，Sr2+的实际取代率接近但略大于理论取代率。随着Sr2+取代量的增大，C4-xŠxA3$的晶胞参数数值呈现线性增大趋势。Ba2+相较Sr2+具有更强转化ye’elimite晶型的能力，在相同的取代量情况下，C4-xBxA3$的晶胞参数数值均大于C4-xŠxA3$晶胞参数。随着Ba2+置换固溶量的逐渐增加，C4-xBxA3S̄的晶面间距逐渐增加。.在硫铝酸盐水泥及熟料复配石膏后膨胀性能的研究方面，硫铝酸盐水泥试件膨胀率在二水石膏与硫铝酸钙摩尔比达到 2.0 以上时会显著提高；水化产物中钙矾石的增长速率以及试件强度会影响试件膨胀率变化，钙矾石增长速率大且强度低的试件膨胀量较大，较大的强度会制约试件的膨胀。掺加无水石膏对促进水泥试件强度发展效果要好于掺加二水石膏；但掺加二水石膏更能促进硫铝酸盐水泥水化。.在水化胶凝机理的研究中，建立了理想状态下C4A3$-C$H2-CH三元系统的理论水化反应范围。初始反应物为1mol C4A3$、a mol C$H2和b mol CH。生成的水化产物AFt、AFm和AH3的物质的量分别为(a/2-b/6) mol、(1+b/2-a-2)mol和(2-b/3)mol。另外，研究表明铝凝胶的含量和水化程度均影响水泥石的强度，当两者达到平衡时，水泥石强度最大。Sr2+的取代会降低C4-xŠxA3$单独水化形成的硬化浆体早期强度，但随着Sr2+取代量的增加，C4-xŠxA3$硬化浆体在28d龄期的强度先增大再减小，其中C2Š2A3$的硬化浆体在28d龄期强度最大；C$H2的掺入会提高硬化浆体的早期强度，但会降低浆体的中后期强度。