火灾后混凝土性能恢复促进技术研究

When exposed to fire, the properties of concreted deteriorate. Compared with the conventional methods for strengthening and repairing fire-damaged concrete structures, the method of improving the recovery of mechanical properties and durability of concrete is time-saving and source-saving, which is of great social and economic significance for repairing and strengthening concrete structure exposed to fire. .In this project, based on the fire-damaged concrete, the recovery mechanism and regular of the mechanical properties and durability of the concrete exposed to fire will be studied. The influence factors of recovery of mechanical properties and durability of fire-damaged concrete will be analyzed. The inorganic compound with high permeability named as concrete performance-modifying agent which was developed in Japan by the applicant, will be studied further. The mechanism of concrete performance-modifying agent improving the properties recovery of concrete exposed to fire will be analyzed with modern analysis technology. The concrete performance-modifying agent will be modified to restore the fire-damaged concrete with different deterioration degrees. The improved recovery extent of the compressive strength, modulus of elasticity, carbonation resistance and chloride penetration resistance of concrete exposed to different heating temperatures, cooling methods and post-fire-curing methods will be investigated. The technology for improving the recovery of the performances of concrete exposed to different heating temperatures, cooling methods and post-fire-curing methods will be developed..The achievements of this project are expected to reveal the mechanism and regular of the recovery in mechanical properties and durability of fire-damaged concrete. And the repairing technology for improving recovery of mechanical performances and durability of fire-damaged concrete will be developed to supply theory for the restoration of concrete structure exposed to fire.

火灾对混凝土的性能造成不同程度的损伤，通过恢复促进技术使火灾后混凝土的力学性能和耐久性能完全或者大部分得到恢复的修复方法，对火灾后混凝土结构的修复加固有着重要的社会意义和经济意义。.本项目以火灾后的混凝土为对象，研究火灾后混凝土的抗压强度、弹性模量、中性化抵抗性、氯离子渗透抵抗性等性能的恢复规律及其影响因素。对申请者在日本所开发的高渗透性无机质混凝土促进剂进一步深入研究，采用现代分析技术，分析促进恢复的机理，改良促进剂的性能，针对遭受不同火灾温度、灭火方式的混凝土开发出相应修复能力的促进剂，提高受火后混凝土力学性能和耐久性能的恢复率，得到火灾后混凝土的力学性能和耐久性能的促进恢复预测模型，进而开发火灾后混凝土力学性能和耐久性能的恢复促进技术。.项目的预期成果将揭示火灾后混凝土力学性能和耐久性能的恢复机理和规律，开发能够促进火灾后混凝土性能恢复的新技术，为火灾后混凝土的修复技术提供理论依据

我国建筑火灾发生数量以及直接经济损失、死亡人数等呈现上升的趋势，火灾所造成的损失也日益严重。已有的研究成果表明，高温下混凝土材料性能的变化使结构的力学性能和耐久性能严重下降，因此，我们要不断研究火灾后建筑物的修复加固技术，提高灾后建筑物的再利用率。.本项目以火灾后的混凝土为对象，研究了火灾后不同种类混凝土的抗压强度、弹性模量、中性化抵抗性、氯离子渗透抵抗性等性能的恢复规律及其影响因素。采用现代分析技术，分析了促进混凝土性能恢复的机理。开发了混凝土性能促进剂，有效提高了受高温后混凝土的抗压强度、弹性模量、抗碳化性能及抗氯离子渗透性能。.通过对不同强度等级（C35，C40，C45，C60）的混凝土及不同材料的混凝土的加热试验，研究不同火灾温度（200、300、400、500、600、700℃）、火灾后的再养护时间（30天、60天和90天）、冷却方式（自然冷却、喷水冷却）对混凝土的力学性能（抗压强度、弹性模量）和耐久性能（中性化抵抗性、氯离子渗透抵抗性）恢复程度的影响，受400℃以下高温后混凝土的耐久性明显下降需要引起重视。.结果表明，发现修复剂的使用能够大幅明显提高受600℃以下高温混凝土的力学性能和耐久性能。与未使用修复剂的混凝土相比，使用修复剂可以使受600℃高温后混凝土的抗压强度提高13%以上，可以使受600℃高温后混凝土的碳化深度降低9mm。火灾温度及冷却方式对混凝土的力学性能和耐久性能的恢复的最大，对于受700℃高温后的混凝土无论喷水冷却还是自然冷却，其耐久性能都无法得到恢复，即使使用修复剂也无法提高其抗碳化性能。.项目的成果揭了示火灾后混凝土力学性能和耐久性能的恢复机理和规律，开发了能够促进火灾后混凝土性能恢复的新技术，为火灾后混凝土的修复技术提供理论依据。火灾后混凝土力学性能和耐久性能火灾后的混凝土促进恢复技术经过加固或修复能够部分恢复其力学性能和耐久性能，能节省大量的社会资源，产生巨大的经济效益。