The Property Research Of Fiber Reinforced Concrete With Slag Power At And After High Temperatures

Experiments and microscopic analysis were carried out to investigate the mechanical properties of fiber reinforced concrete (FRC) with slag powder at normal temperature, during and after high temperatures. Based on experimental studies, the effects of temperature, slag powder content, polypropylene fiber content, steel fiber fraction and concrete strength grade on mechanical properties of FRC with slag powder were systematically analyzed. The main research results are as follows:1. The mechanical properties of FRC with slag powder were tested at ambient temperature. The experiment results shows:slag powder and steel fiber contribute to improving of compressive strength, splitting tensile strength, flexural strength and deformation of FRC with slag powder with different degree; Polypropylene fiber is more beneficial to improve compressive strength, elastic modulus and splitting deformation behavior of FRC with slag powder; The splitting tensile strength, flexural strength and deformation behavior of FRC with slag powder are enhanced along with increasing of concrete strength grade. According to the statistical analysis of experimental results, theoretical equations were proposed to predict compressive strength, splitting tensile strength, flexural strength and elastic modulus of FRC with slag powder at ambient temperature, considering the influences of slag powder content, polypropylene fiber content, steel fiber volume ratio and concrete strength grade.2. The SEM and mechanism analysis of FRC with slag powder subjected to high temperature were researched. The temperature, slag powder, polypropylene fiber, steel fiber and concrete strength grade have different effects on the mass loss rate. The appearance, status, amount, pores and cracks of cement hydrates, such as C-S-H gel, AFt and Ca(OH)2, change with different degree varying to temperature increasing. The spalling and microstructure damage process of FRC with slag powder is revealed to be associated to vaporization, decomposition and migration of the water within concrete.3. The mechanical property experiments were researched of FRC with slag powder during and after high temperature. The results shows:The ratios of compressive strength, splitting strength, flexural strength and elastic modulus are decreased due to high temperature; The content change of slag powder and polypropylene fiber have little effects on the ratios of compressive strength, splitting strength, flexural strength and elastic modulus; The ratios of compressive strength, splitting strength, and flexural strength are improved along with increase of steel fiber volume ratio. Compared with the test results at ambient and high temperature, theoretical equations are proposed to predict compressive strength, splitting tensile strength, flexural strength and elastic modulus at high temperature.4. The deformation performance of FRC with slag powder subjected to high temperature was tested. The influences of temperature, slag powder content, polypropylene fiber amount, steel fiber volume ratio and concrete strength grade on deformation of compression, splitting tension and flexure of FRC with slag powder were researched systematically. Compressive stress-strain equation of FRC with slag powder subjected to high temperature were deduced considering more factors such as temperature, slag powder content, polypropylene fiber content, steel fiber volume ratio and concrete strength grade.