Study On Basic Mechanical Properties Of High Volume Fly Ash Based Geopolymer Concrete And Flexural Properties Of Precast Composite Beams

As we all know,a large amount of coal and electricity will be consumed in the production process of cement.At the same time,a lot of CO2 will be produced in the process of cement production and use.In addition,sulfur dioxide,nitrogen oxide,fluoride,dust and other pollutants in the cement production process will also cause serious environmental pollution.With the rapid development of the national economy,domestic power consumption and power generation demand increases at the same time.Coal-fired power generation is still the main source of domestic power,and the output of power plant fly ash has continued to rise due to the prosperity of coal-fired power generation.Fly ash is a kind of fine solid particles in the flue gas ash produced by the combustion of fuel.If it is directly discharged without control or treatment,it will cause environmental pollution.In this study,fly ash was used instead of cement as concrete cementing material to reduce the amount of cement while realizing waste utilization,reducing a large amount of CO2 emissions in the two processes of Portland cement production and use.Geopolymer is an inorganic polymer with three-dimensional network structure composed of Al O4 and Si O4 tetrahedral units.Although there have been many researches on geopolymers at home and abroad in recent years,most of the existing research focuses on the geopolymer reaction mechanism and micro-mechanism.The research on geopolymer concrete is still to be improved,and the research on the bending performance of geopolymer concrete composite beams is even less.Therefore,in accordance with the concept of green development and the application of geopolymer concrete to achieve the purpose of high-value utilization of fly ash,the research starts from the composition of raw materials,mix ratio,workability,mechanical properties and geopolymers.The research on flexural performance of composite beams and other aspects is carried out to innovate the rational application of fly ash-based geopolymer concrete in prefabricated component products and fabricated component systems.And then,finite element analysis was used to verify the applicability of the existing concrete code and numerical simulation analysis to the geopolymer-ordinary concrete bi-material composite beam.The research shows that the geopolymer performance can meet the target requirements through the appropriate mix proportion design,and the bending test also preliminarily proves that the flexural performance of geopolymer is not significantly different from that of ordinary concrete beam.The main research contents of this article are as follows:(1)Research on the mechanical properties of geopolymer concrete with different metakaolin content.Focusing on the influence of alkali-gel ratio,curing temperature,category of fly ash,and mechanical excitation on the mechanical properties such as flowability,compressive strength,split tensile strength,and elastic modulus of fly ash-based geopolymer concrete on the basis of 30% metakaolin content.Established a corresponding compressive strength prediction model and proposing a mix proportion design suitable for engineering applications;(2)Study on the flexural properties of 8 specimens,including 1 ordinary concrete beam,1 ordinary concrete composite beam,1 fly ash based geopolymer concrete beam,5 geopolymerordinary concrete composite beams,which focused on the flexural failure mechanism,crack development,member deformation,reinforcement and concrete strain of the beams under the control of different parameters;(3)Based on the software ABAQUS and calculation models at home and abroad,a twodimensional finite element model which can be used to analyze the bending performance of bimaterials composite beams is established and compared with the test results.On this basis,further analysis of the influence of the composite height and reinforcement ratio on the flexural performance of the GPC-OPC composite beam has been made.Based on the results of experiment and finite element analysis,a novel prefabrication method,construction technology and design process of fly-ash based GPC-OPC composite has been put forward,and an invention patent has been applied,which provides reference for engineering application.