Mechanical And Thermal Properties Of Short E-Glass Fiber Reinforced Geopolymer Composites

First,this work reviewed the thermal and mechanical behaviors of fiber reinforced geopolymers at high temperature.Firstly,the thermal properties of fiber reinforced geopolymers in terms of mass loss,thermal expansion,and thermal conductivity after high temperature were explained.Secondly,the mechanical properties of residual compressive strength relationship of different types of fiber reinforced geopolymer after high temperature were analyzed.Finally,the microstructure and mineralogical characteristics of geopolymers upon heating were interpreted according to the changes of microstructures and compositionsSecond,in this study,E-glass fiber reinforced geopolymer composites(E-GF/GP)were prepared by strong stirring method,and the effects of E-glass fiber contents and lengths on the microstructure,flexural and compressive strength of the E-GF/GP composites were investigated systematically,as well the combination effect of the addition of different content of foaming agent(H₂O₂)and fixed content of surfactant(Triton X-100)on the thermal properties,compressive strength and pore characteristic of the E-GF/GP composites was also elucidated.The results show that the E-glass fiber addition has little influence on phase composition of the GP composites,but a suitable content and length of the fiber will result in the improved flexural and compressive strength,and when the E-glass fiber content and length is 2.0 wt.%and 3 mm,respectively,flexural and compressive strength of the E-glass fiber/GP composite is enhanced by 121.6%and 70.9%,respectively,compared with the neat geopolymer.The addition of H₂O₂ and surfactant produced a geopolymer foam with acceptable compressive strength(1.5-7.3 MPa).Geopolymer foam has a porosity of 55.9 to 70.2%and a thermal conductivity of 0.123 to 0.213 W/(m·K).Pore structure,size and distribution are governed by H₂O₂ and the small surfactant doses which have a great influence on compressive strength.A narrower pore distribution and smaller pore diameter were achieved when both the foaming agent and surfactant were used instead of the foaming agent alone.The pore size and distribution varied greatly with differing H₂O₂contents.The surfactant showed a characteristic pore-stabilizing effect at low H₂O₂(<1.0wt.%)which diminished at high H₂O₂ content.In terms of thermal conductivity,even with the increased porosity at high H₂O₂ content and with the addition of surfactant,the thermal conductivity did not show a significant decrease due to interconnected pores as a result of pore coalescence.