自密实混凝土抗碳化性能及抗氯离子侵蚀性能研究

A series of self-compacting concrete speciments incorporating mineral admixtures will be designed. The mineral admixtures are in the form of only fly ash, both fly ash and ground granulated blast-furnace slag, as well as fly ash, slag and silica fume. Based on the accelerated carbonation test method and ASTM C1202 test method, the effects of different type and use level of mineral admixture, water to binder ratios, curing ages, tensile stress rates, and compressive stress rates on the carbonation resistance and chloride ion permeability resistance of SCC will be systematically investigated, and the results are also compared to a plain concrete. Furthermore, the mix design method of SCC with high carbonation resistance and high chloride ion permeability resistance will be proposed. Carbonation mechanism of SCC will be determined by using the methods of water absorption test, traditional phenolphthalein test, apparent pH test, thermogravimetric analysis and X-ray diffraction analysis. Based on the results, both positive and negative effects cauesed by mineral admixtures on carbonation of SCC, and the relationships among three regions of fully carbonated zone, partially carbonated zone and non-carbonated zone will be analysed. The carbonation depth and chloride ion permeability prediction models of SCC containing massive mineral admixtures will be established, and the prediction models are considered with the influence of the chemical reaction degree of the cement and mineral admixtures, the tensile or compressive stress rates, the time variability of the carbon dioxide concentration, and the microclimatic conditions of the concrete structure. The project will solve the key technical problems of SCC, and it is also important to ensure the durability of the self-compacting concrete structure.

设计不掺矿物掺合料、单掺粉煤灰、复掺粉煤灰与矿渣或硅灰的自密实混凝土，通过快速碳化试验和ASTM C1202电通量试验，揭示矿物掺合料品种和掺量、水胶比、养护龄期和拉压应力水平等因素对自密实混凝土抗碳化性能和抗氯离子侵蚀性能的影响规律，提出高抗碳化性能和高抗氯离子侵蚀性能的自密实混凝土配合比设计方法；通过混凝土吸水率试验、孔溶液的表观pH值测定、热分析、X射线衍射等测试方法并与传统的酚酞测试法结合，揭示自密实混凝土碳化机理，掌握矿物掺合料对自密实混凝土抗碳化性能的正负效应及混凝土内部完全碳化区、部分碳化区、未碳化区的分布；建立考虑水泥及矿物掺合料水化程度、拉压应力水平、二氧化碳浓度的时变性、混凝土结构所在微环境条件等综合因素联合作用下的大掺量矿物掺合料自密实混凝土的碳化深度和氯离子侵蚀预测模型。本项目研究对解决自密实混凝土工程的关键科学技术，确保自密实混凝土结构的耐久性具有重要意义。

设计了不掺矿物掺合料、单掺粉煤灰、复掺粉煤灰与矿渣或硅灰的自密实混凝土，通过快速碳化试验和ASTM C1202 电通量试验，揭示矿物掺合料品种和掺量、水胶比、养护龄期和拉压应力水平等因素对自密实混凝土抗碳化性能和抗氯离子侵蚀性能的影响规律，提出了高抗碳化性能和高抗氯离子侵蚀性能的自密实混凝土配合比设计方法；通过混凝土吸水率试验、孔溶液的表观pH 值测定、热分析、X 射线衍射等测试方法并与传统的酚酞测试法结合，揭示自密实混凝土碳化的机理，掌握了矿物掺合料对自密实混凝土抗碳化性能的正负效应及混凝土内部完全碳化区、部分碳化区、未碳化区的分布；建立了考虑水泥及矿物掺合料水化程度、拉压应力水平、二氧化碳浓度的时变性、混凝土结构所在微环境条件等综合因素联合作用下的大掺量矿物掺合料自密实混凝土的碳化深度和氯离子侵蚀预测模型。本项目研究对解决自密实混凝土工程的关键科学技术，确保自密实混凝土结构的耐久性具有重要意义。