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摘要混凝土中掺加纤维可有效地抑制混凝土裂缝的扩展，提高混凝土的韧性和抗变形能力，但环境介质侵蚀下纤维混凝土及其结构的服役耐久性，特别是在软水环境下的钙溶蚀问题一直没有得到工程界的重视。围绕水环境下纤维混凝土钙溶蚀所引起的耐久性退化问题，本文设计制作了一种三速循环输水腐蚀装置，开展了不同纤维掺量混凝土圆柱试件的浸泡和流水冲刷加速腐蚀试验，测试了溶蚀深度、孔隙率、抗压强度和微观形貌等溶蚀参数，分析了纤维掺量及腐蚀溶液流速对溶蚀进程及力学性能的影响，主要研究内容及结果如下：43112
(1) 利用酚酞滴定法，定期测试不同流速腐蚀下的各纤维掺量水泥砂浆试件的溶蚀深度，获得了不同流速溶液腐蚀下，各纤维掺量水泥砂浆试件溶蚀深度随时间的变化规律。结果表明，流水腐蚀下试件的溶蚀深度大于浸泡于溶液中的试件腐蚀深度，流动水能够加速试件的溶蚀进程。
(2) 运用饱水干燥称重法，定期测试四种流速作用下不同掺量的纤维水泥砂浆试件孔隙率，获得了各试件孔隙率随溶蚀时间的变化规律。结果表明，与掺纤维的水泥砂浆试件相比，未掺纤维的水泥砂浆试件的孔隙率增加较小，密实度较好，纤维的掺入没有提高水泥砂浆的抗溶蚀性能。
(3) 采用EDTA钙离子滴定法，定期测定了腐蚀溶液中的钙离子浓度，获得了溶蚀过程中试件的钙离子溶出量，结果表明，未掺纤维的水泥砂浆试件的钙离子溶出量小于掺纤维的水泥砂浆试件，这一结果与以孔隙率表征的钙溶蚀过程测试结果基本一致。
(4) 设计制作了一种刚度较大的腐蚀混凝土应力-应变全曲线测试装置-751`文~论^文.网www.751com.cn，开展了不同溶蚀时间的各纤维掺量水泥砂浆试件应力-应变全曲线的测试，结果表明，该装置可以测定腐蚀样品的应力-应变全曲线，从获得的曲线可以看出，掺纤维水泥砂浆的韧性和延性均高于未掺纤维的水泥砂浆。
(5)根据Gerard固液平衡曲线和Fick定律，并利用有限差分法，建立了掺纤维水泥砂浆圆柱体试件的钙离子传输方程及其数值求解方法，运用MATLAB语言，编制了相应的计算分析程序，分析了6M氯化铵溶液浸泡腐蚀条件下水泥砂浆试件中孔隙率、溶蚀深度、钙离子溶出量等溶蚀参数的时空变化规律，并与实验测试结果进行了对比分析，验证了模型的合理性。
关键词 钙溶蚀 PVA纤维 孔隙率 溶蚀深度 抗压强度 模型
毕业论文外文摘要
Title Study on Leaching Experiment of Fiber Reinforced Concrete Subjected to Soft Water Environment
Abstract
Fiber can better prevent the development of concrete cracks and improve the toughness of concrete and the ability to resist deformation. However, service durability of fiber reinforced concrete structure under the erosion of environment medium, especially the calcium leaching in soft water environment has not attracted the attention of the engineering community. Around durability degradation problem of fiber reinforced concrete caused by calcium leaching in soft water environment, a corrosion device for three speed circulating water supply was designed, and an accelerated corrosion experiment of immersion and water erosion of concrete specimens with different fiber content was carried out. Effects of fiber content and corrosion solution flowing rate on leaching process and mechanical properties were analyzed. The main research contents and results are as follows:
(1) Phenolphthalein titration test was conducted to investigate corrosion depth of cement mortar specimens with different fiber content under different flowing velocity regularly, and the variation of leaching depth with time was obtained. The experimental result shows that, compared with the cement mortar in stationary solution, the cement mortar in flowing solution has higher corrosion depth, indicating that the flow of water has accelerated the process of calcium dissolution.