Study On Mechanical Properties Of Fiber Reinforced Granulated Slag Concrete After High Temperature

In order to achieve the sustainable development of concrete industry, the fine mineral admixtures considered as a green building material have been coming to the people's attention day by day, and have been a focus of research recently. Granulated blast furnace slag which is a kind of fine mineral admixtures has high surface energy, excellent finishability and good pozzuolana activity. When added into the concrete to replace the cement equally, it can improve the mechanical properties, workbility and endurance of concrete. The granulated blast furnace slag is produced from the waste stock of the industry, and has a low cost, so it is an ideal material of high performance concrete (HPC). However, as long with the development of the research and application of HPC, its ductility and fire performance are asked to meet higher demand. HPC is incorporated with fiber to use the strengthen and toughen mechanism of fiber to improve the ductility and high temperature performance of concrete.Through the addition of the hybrid fibers (steel fiber and polypropylene fiber) to the granulated slag concrete, a new fiber reinforced high performance concrete named fiber reinforced granulated slag concrete is produced, and its mechanical properties after exposure to different high temperature are studied. The following aspects are investigated as the focul points in this thesis:(1) The research of the high temperature performance of concrete both from home and abroad in recent years are reviewed and analyzed.(2) The exterior appearance and mass loss of fiber reinforced granulated slag concrete after different target temperature is observed and studied.The results show that the higher the temperature is, the more serious the deterioration of the exterior appearance and mass loss of the concrete is, the addition of steel fiber and polypropylene fiber can effectively prevent granulated slag concrete from spalling and maintain its integrity at high temperature.(3) Through measuring the compressive strength, splitting tensile behavior, flexural behavior and elastic modulus of fiber reinforced granulated blast furnace slag concrete after high temperature, the influences of temperature, rate for replacement of cement of slag powder, fiber type and volume fraction and base strength grade on the residual mechanical properties of concrete is analyzed. It is found that the higher the temperature is, the more serious the deterioration of the mechanical properties of concrete is; the enhanced impact of slag powder on the strength of concrete after high temperature is verified; the addition of steel fiber and polypropylene fiber can increase the residual mechanical strength of fiber reinforced granulated slag concrete, and improve its deformation behavior after high temperature. (4) Based on the experimental data, the differences between normal and high temperature performance of fiber reinforced granulated slag concrete are investigated, and expressions of the each mechanical strength and elastic modulus after high temperature are regressed(5) The deterioration mechanics of the mechanical properties of the granulated slag concrete after high tempreture is studied.