Study On Material Properties Of Fiber Reinforced Geopolymer Concrete

In recent years,with the increasing attention to environmental issues,ordinary Portland cement has gradually become difficult to meet the Environmental requirements,and geopolymers are receiving more and more researchers' attention because of their excellent performance.Geopolymer is an inorganic non-metallic material composed of three-dimensional network composed of SiO4 and AlO4 tetrahedral units.It has excellent durability,high temperature resistance properties and early strength.At the same time,it has the advantages of wide source of preparation materials and during production it has the advantages of low energy consumption and low pollution.However,the geopolymer concrete is similar to ordinary concrete in that it has the disadvantages of high brittleness and low tensile strength.In view of this,PVA fiber and steel fiber were added into the geopolymer concrete in order to achieve the purpose of toughening and modifying the geopolymer concrete.In the trial,alkali activator(prepared from NaOH and sodium silicate),metakaolin,fly ash and aggregates are used as the main raw materials,then adds different volume of PVA fiber and steel fiber.Finally,fiber reinforced geopolymer concrete with good performance was prepared.The effects of different content of PVA fiber and steel fiber on the basic mechanical properties and fracture properties of fiber-reinforced geopolymer concrete has been studied by a large number of experiments.The main research contents are as follows:(1)The preparation method of geopolymer concrete and the optimum test mix ratio were determined,and the volume content of PVA fiber and steel fiber was determined.(2)The influence of PVA fiber and steel fiber on compressive strength of geopolymer concrete was investigated by standard cubic compression test,and the influence rule of fiber content was revealed.(3)The effect of PVA fiber and steel fiber on tensile strength of geopolymer concrete was studied by standard cube splitting tensile test.The brittleness characteristics of geopolymer concrete with different fiber content are analyzed based on the tension-compression ratio curve.(4)The flexural strength test of non-standard specimen with the size of 100 × 100 × 400 mm was carried out.Based on the test,the influence of PVA fiber and steel fiber on the flexural strength of geopolymer concrete was analyzed,and the influence rule of fiber content was revealed.(5)The influence of PVA fiber and steel fiber on the elastic modulus of geopolymer concrete was studied by measuring the elastic modulus of standard prismatic specimen under static compression.The correlation between compressive strength and elastic modulus of geopolymer concrete with the same fiber content was analyzed.(6)Through the three-point bending test of pre-notch trabecular specimen with the size of 100 × 100 × 400 mm,the double-K fracture model is adopted.The effective crack length,initiation fracture toughness,instability fracture toughness and other parameters are used as the evaluation indexes.The effect of PVA fiber and steel fiber on the fracture properties of geopolymer concrete was studied,and the rule of the influence of fiber content on the fracture parameters was revealed.