【作者】 农金龙；

【导师】 易伟建； 黄政宇；

【作者基本信息】 湖南大学 ， 结构工程， 2014， 博士

【摘要】 聚合物乳液或胶粉掺入新拌和普通混凝土、砂浆或水泥净浆,亦可复掺外加剂或矿物掺合料,可使普通混凝土、砂浆或水泥净浆性质较大地改变,性能显著地改善,其制成的复合材料用作粘结材料,称为聚合物改性水泥基粘结复合材料(Polymer-modified cement-based bonding composite,简称PCBC)。本文以丁苯PCBC为重点,对几类PCBC粘结性能进行系统的试验研究和理论分析,其主要内容和创新成果如下：1.基于系统的配比试验,提出了聚合物改性水泥基粘结砂浆(Polymer-modified cement-based bonding mortar,简称PCBM)较适宜的配比,研究几类PCBM短期粘结性能。通过试验和理论分析可得：(1)聚灰比、水灰比、胶砂比等聚合物砂浆配合比的变化明显地改变包括粘结强度在内的砂浆强度；高效减水剂等外加剂的复合改性,显著地改善部分聚合物砂浆早期粘结性能；UEA和SF等矿物掺合料对聚合物砂浆早期粘结性能的改性作用效果不明显；混用外加剂FDN及矿物掺合料SF和UEA对各种聚合物砂浆粘结改善作用差异较大。(2)几乎所有试验涉及的PCBM,硬化前的拌合物都有特殊的性质和特点,硬化后的也有独特的力学性能,明显地区别于普通砂浆,在选用适当的配比和保持良好的养护环境等条件下,可以显著改善早期粘结性能。2.将聚合物砂浆的拌合物稠度和密度、粘结养护制度、配比、外加剂、矿物掺合料、粘结强度、本体抗压和抗折强度以及户外5a龄期粘结,有机地融入聚合物改性水泥基粘结复合材料短期和长期粘结性能研究中,形成了较系统的粘结性能研究体系,得到如下新型粘结材料：粘结性能优良的丁苯砂浆,不同粘结性能的丙烯酸、纯丙和氯丁砂浆,潮湿环境及水中可固化的液态环氧树脂,没有缓凝现象且本体强度不降低的NP砂浆。3.通过试验研究了丁苯改性水泥基材料长期粘结性能复杂的作用机理。结果表明：丁苯水泥净浆斜剪、直剪、抗弯、轴向拉伸及丁苯混凝土劈裂强度性能优越,其抵抗大面积、大体积混凝土修补加固所产生的复杂应力系统破坏的能力突出；丁苯砂浆的长期水泥水化程度较高和其特有的、有益的水泥水化规律相关；丁苯砂浆受热和干缩变形规律不损害其长期粘结性能,有些变形甚至对长期粘结性能有益；丁苯砂浆的粘结界面电镜照片和显微硬度试验结果显示其粘结效果良好,与其宏观良好的长期粘结性能相一致。提出并运用了薄弱幅度和薄弱指数两个性能参数,对丁苯砂浆粘结界面显微硬度试验结果进行分析,进一步证实丁苯砂浆具有良好的长期界面粘结质量,推证了其粘结界面过渡区具有自我完善的功能,动态地解释了其长期粘结性能机理。提出并运用了丁苯砂浆粘结界面模型。更多还原

【Abstract】 Polymer-modified cement-based bonding composite(PCBC) is defined as that polymer powders or latex, some time with additive or mineral admixture, are incorporated to modify property of common concrete, mortar or paste hugely and improve its performance markedly, which is used as new-to-old concretes or mortars bonding materials. This dissertation focuses on the systemic experiments and theoretical analysis on the bonding performance of some PCBC, especially Styrene-Butadiene-Rubber(SBR) PCBC. The main research content and innovative achievements can be summed up in the following aspects:1. The more proper proportion of polymer-modified cement-based bonding mortar(PCBM) is brought forward to research on its short-time bonding performance, based on systemic proportion of mortar in the experimental investigation, by giving priority to achieve a better short-time bonding effect. The interfacial bonding performance of PCBM to the old mortar is affected under the conditions of different curing systems, bond methods, aging, bonding materials’ proportion and variety, admixture and mineral additive. It is found experimentally and theoretically that:(1) Change in the proportion of PCBM, such as polymer cement ratio P/C, water cement ratio W/C and sand cement ratio S/C, inflects markedly mortar’s strength, including bond strength. The short-time bonding performance of some PCBM is improved observably by using high efficiency water reducing agent at the same time, hardly improved by using mineral additives, such as UEA and SF, and improved differently by combining FDN, SF and UEA together.(2) The short-time bonding performance of PCBM with proper proportion and in well curing environment is almost improved with contrast to that of common mortar while it is different between before and after mortar harden.2. Long-time and short-time bonding performance of PCBC are researched systematically, involved of curing systems, bond methods, aging, bonding materials’ proportion and variety, additive and mineral admixture, bond strength, body flexural strength and body compressive strength,5years age in out-door bonding. As a result, some new building bonding materials are found. SBR modified mortar has good bonding performance. Acrylic latex, pure acrylic latex and chlorobutyl latex modified mortar have good bonding performance while they are in the fitting bonding conditions. Liquid epoxide resin can solidify in damp environment or in water so that its well bonding performance is validated by test. Bond strength of poly-oxane polymer powder(denoted as NP) modified mortar is reformed markedly while its body strength does not become below with contrast to that of common mortar.3. The long-time interfacial bonding mechanism of Styrene-Butadiene-Rubber(SBR) latex modified cement-based concrete/mortar/paste used and strengthed in RC structure is studied by some tests in this paper. The findings indicates that SBR latex modified cement-basedd mortar has achieved a good result of long-time interfacial bonding performance. The slanting shear、flexural、direct shear and direct axle tension tests are adopted to approach SBR latex modified cement-based paste resistance to the breaking stress in strengthed RC structure. At the same time, splitting strength of SBR latex modified cement-based concrete is high too. Semi-adiabatic exothermal hydration test is used to study the hydration interaction between SBR and cement in the mortar. The dry shrinkage and heating deformation tests are utilized to research characteristic of SBR latex modified cement-basedd mortars encountered with temperature and humidity change. Scanning electron microscope(SEM) is employed to read the microscopic structure of bonding interfacial transitiation zone(BITZ) in SBR latex modified cement-based mortar strengthed in RC structure. After microhardness test is utilized to research microhardness of bonding interfacial transitiation zone(BITZ) in SBR latex modified cement-based mortar strengthed in RC structure, weakness extent and weakness index for microhardness of BITZ are brought forward and made use of. It is confirmed again that there is long-time good bonding performance and function to self-repair and to self-perfect in the bonding interfacial transitiation zone(BITZ) of SBR latex modified cement-based mortar. Long-time interfacial bonding mechanism is thoroughly discussed to base on data of these associated tests. Research on long-time interfacial bonding mechanism of SBR modified cement-based composite help to understand its long and short-time bonding performance. The model for new-to-old bonding interface of SBR modified mortar is brought forward and used.更多还原