Research On Fire Disaster Mechanism Of Self-thermal Insulation Sandwich Wall With TRC Element

Textile reinforced concrete (TRC) is a new high performance cementitious composite material that attracts much attention in recent years. TRC has many advantages such as superior corrosion resistance, light-weight, high loading-bear capacity and ductility. The cover thickness of TRC members depends primarily on the necessary value to ensure a proper anchorage of the reinforcement, which makes TRC widely used in the thin-walled structure with light-weight in the field of building envelope. The fire resistance and high temperature mechanical properties of TRC members as an architectural component must be guaranteed. Therefore, it is obviously significant to study on fire behavior of TRC members. For this purpose, this thesis took an experimental study on the mechanical performance of TRC members after exposure to high temperatures. Moreover, exploratory research on the physical and mechanical property and fire resistance of TRC self-thermal insulation sandwich wall, was carried out based on some experiments. The research is supported by the "twelfth Five-Year" national science and technology supporting project (No.2012BAJ13B04) and the key project of Zhejiang province science and technology program (No.2011C11083). The main contents and conclusions of this study include:1.. The high-temperature performance of fine grained concrete was studied by using different cementitious materials and adding different short fibers. The results show that the residual compressive strength of specimens using high alumina cement as main cementitious material is superior to that of specimens using ordinary Portland cement when the target temperature is higher than 600℃, and so do the residual flexural strength. Furthermore, the target temperature is higher, the advantage of specimens using high alumina cement is more obvious. The addition of short fibers can improve the residual flexural strength of fine grained concrete at room temperature and after exposure to high temperatures. Adding 1.0% short steel fibers is the best way to improve the residual flexural strength of specimens.2, Study on the four-point bending mechanical properties of TRC thin-plates after exposure to different temperatures by means of unstressed residual test (URT). Results demonstrate that the bursting ratio of TRC thin-plates with epoxy resin-impregnated fiber is 100% when the target temperature reaches 300 ℃. Bending capacity of TRC thin-plates with non-impregnated decrease evidently when the target temperature reaches 400℃-500℃, and still remain 20% of those in room temperature when the target temperature reaches 800℃. Results of microstructure observation show that the surface flaws of carbon fiaments, the matrix decomposition together with the weak bond behavior between fibers and matrix are affected by elevated temperatures. These three factors result in the decline of the bearing capacity of TRC thin-plates with non-impregnated.3、Four-point bending tests were carried out on TRC thin-plates with different cementitious materials after exposure to different temperatures. Thermogravimetric analysis, pore distribution and micro-structural analysis were performed to evaluate the degradation of the damaged TRC thin-plates using thermogravimetric analyzer, mercury intrusion porosimeter and an environmental scanning electron microscope (SEM), respectively. The results indicate that using high alumina cement as matrix can effectively reduce the thermal degradation of the matrix at temperatures above 600 ℃, compared with that using ordinary Portland cement as matrix.4、An experimental study on the bending mechanical behavior of TRC Thin-plates with short fibers (carbon fibers; steel fibers; basalt fibers and PP fiber) and corresponding micro analysis were carried out at room temperatures and after exposure to high temperatures. It is discovered that the bearing capacity of TRC specimens can be improved by adding short fibers, either at room temperature or after exposure to high temperatures. The more the short fibers is mixed, the better the bearing capacity and cracking stiffness are improved at room temperatures, but does not suit for short basalt fibers and PP fibers. Moreover, adding 1% short carbon fibers is the best way to improve TRC thin-plates after exposure to high temperatures.5、The physical and mechanical properties of TRC panel (softening coefficient of fine grained concrete; moisture content of TRC element; freeze-thaw resistance; compressive strength and thermal conductivity of TRC specimens) were tested, respectively. The test results can meet the corresponding standard requirements. Preliminary calculation of thermal performance parameters of TRC self-thermal insulation sandwich wall is finished, and the reasonable thickness value of the sandwich wall is determined. Furthermore, the technical process of TRC self-thermal insulation sandwich wall is also put forward.6. The fire-resistant property of TRC self-thermal insulation sandwich walls was investigated through fire-resistance tests. The effects of factors (different reinforced materials; panels with or without PP fibers; different thicknesses of sandwich cores and panels and the fire surface with or without fire-retardant coatings) on fireproof limit and failure state of specimens are discussed. The ABAQUS 6.10 software was applied to simulate heat transfer process under fire. Consequently, the calculated results are in good agreement with the experimental results.