【作者】 贺奎；

【导师】 杨辉；

【作者基本信息】 浙江大学 ， 材料物理与化学， 2014， 博士

【摘要】 钢筋混凝土结构作为土木工程领域最常用的结构形式,其施工与服役环境极其复杂,恶劣环境中混凝土的耐久性问题尤其突出,已成为国内外研究热点。目前恶劣环境下混凝土耐久性的研究主要着重在混凝土结构的破坏机理,对其防护技术的研究则主要集中从无机材料方面改善混凝土的密实度或仅利用其中一种外加剂进行改善,缺乏能对混凝土耐久性改善的有机功能材料的设计研发及有机无机协同防护机理研究。鉴于此,本文设计研发了一系列有机功能材料,并分析了其对混凝土的防护作用机理。本文的主要工作及结论如下：(1)合成了一种新型酯类外加剂,并对其掺入后混凝土的流动性、强度及抗腐蚀性能进行研究。研究表明,该外加剂在促进混凝土材料低温下强度发展的同时,改善了混凝土的孔结构,提高了基体密实度,可有效解决低温环境下混凝土硬化缓慢,早期强度低而引起的耐久性问题。(2)对内掺硅烷防水剂水泥基材料的吸水性、表面特性及耐酸侵蚀性能的研究结果表明,掺入硅烷后水泥基材料的吸水率及毛细吸水系数降低,润湿角呈现钝角,抗硫酸侵蚀性能显著提高；SEM、XRD等微观试验结果显示,硅烷延缓了侵蚀产物的生成,表明硅烷可降低H+和S042-进入水泥基材料内部的速率,提高材料耐酸侵蚀的性能。(3)依据气相液相扩散机理优选了迁移速率与阻锈性能相匹配的苯甲酸单乙醇胺作为迁移型阻锈剂。UV-vis、SEM、EDX等微观试验分析表明,苯甲酸单乙醇胺可通过扩散迁移并富集在钢筋表面形成保护膜,防止氯离子引起钢筋(钢纤维)锈蚀。苯甲酸单乙醇胺对混凝土的抗压强度、含气量和凝结时间等基本性能无影响,但可减少混凝土的收缩,提高其抗海水侵蚀能力,同时可改善钢筋(钢纤维)与混凝土界面,有效阻止外界离子侵入到钢筋或钢纤维表面,提高钢筋混凝土或钢纤维混凝土的耐久性。(4)通过合理的分子结构设计,引入羟氨基聚醚和潜伏性固化剂,制备了可手工涂覆的新型聚氨酯-脲有机涂层,并对涂层进行了表征。进一步研究了聚氨酯-脲的力学性能、抗老化性能及涂覆后混凝土的抗硫酸侵蚀能力。结果表明,该涂层性能优异,与混凝土具有良好的粘结性,粘结强度高达3.2MPa；热氧、紫外光照经过一段时间处理后涂层得到进一步熟化,拉伸强度有较大提高；相对于环氧涂覆混凝土试件,聚氨酯-脲涂覆试件在H2S04溶液中浸泡28d后的质量损失率降低32.6%,抗压强度提高22.7%,能够显著提高混凝土的抗酸侵蚀能力。更多还原

【Abstract】 As the most commonly used structure in civil engineering, reinforced concrete structure and its construction process is suffering extreme complex environment, which causes severe durability problem. The durability of reinforced concrete structure in harsh environment has become a research hotspot at home and abroad. Present study mainly focused on the failure mechanism of concrete. The protective technology researches are mainly focus on improving the compactness or enhancing the durability of concrete by using only one admixture. The designing of organic functional materials and improving the durability of concrete by development of organic functional materials and organic and inorganic coordination are relatively infrequent. In this thesis, a series of organic functional materials were designed and the mechanism of its protection was homologous clarified. The main work and conclusions are as follows:(1) A novel esters admixture (SE) was synthesized. The fluidity, strength and corrosion resistance of concrete with SE was studied. The results showed that, compared with the common early strength agent such as TEA, inorganic salts etc., SE was able to promote the strength development of concrete at low temperatures. The pore structure and compactness of concrete were improved by SE correspondingly, which was able to solve the durability problem of concrete caused by low temperature.(2) The water absorption, surface characteristic and acid resistance of cementitious composite modified by silane-based admixture were studied. The results showed that the water absorption and capillary water absorption index of cementitious composite were lowered by silane-based admixture. The wetting angle was observed as obtuse angle, which indicated that the surface turned to be hydropHobic. The results of SEM、 XRD tests showed that the formation of corrosion products was restrained by silane. The permeability of H+and SO42-was prevented, which improved the corrosion resistance of cementitious composite material.(3) Based on the diffusion mechanism in gas and liquid pHase, benzoic acid monoethanolamine was selected as migrating corrosion inhibitor. The results of UV-vis, SEM and XPS showed that benzoic acid monoethanolamine formed protection film by diffusing and gathering onto the surface of reinforcing steel, which prevented the corrosion of steel bar and steel fiber. Benzoic acid monoethanolamine did not have negative effect on the compressive strength, air content or setting time of concrete. The shrinkage of concrete was reduced, and the formation hydration products were promoted by benzoic acid monoethanolamine, which prevent outside intrusion ions effectively and improve the durability of concrete.(4) A novel polyurethane urea organic coating that can be coated manual was synthesized by proper molecular structure design. Hydroxyl amino polyether and latent curing agent was induced, and the newly synthesized coating was analyzed. The mechanical properties, aging properties of the coating and sulfate erosion resistance of concrete with the coating were studied, respectively. The results showed that, polyurethane urea organic coating had satisfactory performance. The bonding strength of coating and concrete reachesd3.2MPa, which indicated remarkable bonding performance. The tensile strength of coating was further enhanced by thermal aging and UV light processing. After immersed in2%sulfuric acid solution for28d, the mass loss rate of specimens with polyurethane urea coating declined32.6%, the residual compressive strength increased22.7%compared with the concrete specimens with epoxy coating. The acid erosion resistance of concrete was obviously enhanced by polyurethane urea coating.更多还原