| Portland cement is widely used in the process of modern infrastructure construction.However,the raw materials and production technology used in Portland cement aggravate the waste of existing resources and environmental pollution,which is contrary to the green development and ecological civilization construction concept proposed in China this year.A large number of slag will be produced in the process of blast furnace ironmaking,and a large amount of fly ash will be generated in the process of power generation of thermal power plants.If these industrial by-products can be used as treasure in civil engineering construction,it is in line with the theme of the contemporary sustainable development strategy.Alkali-activated slag concrete is a new green building material which takes slag as the main cementiting material,fly ash as admixture,and stimulates the activity of slag with strong alkali solution,and adds coarse and fine aggregate.It has many advantages,such as early strength,fast hardness,corrosion resistance,low hydration heat and good stability,but its shrinkage deformation is limited to its application and popularization.In this paper,the defects of drying shrinkage of alkali slag concrete are improved by adding steel fiber.A series of research work is carried out on this basis,as follows:(1)Taking the steel fiber content as the variable,the cube compressive strength,prism compressive strength,elastic modulus and Poisson’s ratio of alkali slag steel fiber reinforced concrete are measured.On this basis,the development of micro cracks in the specimen is qualitatively and quantitatively described,and the influence mechanism of steel fiber on its mechanical properties under different content is analyzed and determined.The results show that the steel fiber has a good effect on strengthening,toughening and cracking resistance of alkali-activated slag concrete.(2)The stress-strain relationship test of alkali-activated slag concrete with different steel fiber content was carried out,and the mechanical behavior of the material was described by introducing damage variable D.Weibull distribution was used in the rising section of curve,and Cauchy distribution was used in the descending section D.the damage constitutive model of alkali-activated slag steel fiber reinforced concrete was established.The final theoretical curve was in good agreement with the test curve.(3)Simply supported beams with 0%,0.5% and 0.9% steel fiber content are selected to carry out the experimental study on the flexural mechanical properties of alkali-activated slag steel fiber reinforced concrete beams.The stress-strain evolution law and crack development of the beams in the bending process are revealed.The experimental results show that the plane section assumption is still applicable to alkali-activated slag steel fiber reinforced concrete beams,and the addition of steel fiber can improve the flexural capacity and increase the flexural strength Ductility of the beam.(4)Ansys is used to establish the separation model of steel fiber reinforced concrete beam,the damage constitutive model of concrete is used,and the double broken line model is used to analyze the bending mechanical properties of steel fiber reinforced concrete beam.The final finite element analysis results are in good agreement with the experimental results. |
