Fracture Test And Theoretical Analysis On The Aligned Steel Fiber Reinforced Cement-based Composites

Steel fiber cement-base material is a new type of composite material,which is mixed into the uniform random distribution of steel fibers in the cement matrix.Lots of researches have proved that the properties of aligned steel fiber reinforced cement-based composites are superior to those of ordinary random distribution steel fiber reinforced cement-based composites.Combined with the three-point bending beam test and the theoretical analysis,the crack propagation processes and material fracture parameters were studied.What's more,this work supported by the science and technology research key project of high school in hebei province.(ZD2015028).and the national natural science foundation of China.(51578208).The specific contents as follows:(1)First studied the fracture properties of the matrix.The fracture properties of aligned steel fiber cement-based composites matrix was analysed based the experimental results and fracture parameters;Besides the size effect of cement matrix were studied;The results show that the fracture parameters of cement mortar matrix have certain size effect.(2)Through applying the uniform magnetic field to the cement mixture to change the direction of steel fibers in cement-based mixture,achieve the aligned steel fiber reinforced cement-based composites.The crack propagation processes of aligned steel fiber reinforced cement-base composites were studied combined with the three-point bending beam test,and compared the test curves and the fracture parameters of the cement-based composite materials for orientation and random,two kinds of steel fiber distribution forms;It was shown that the fracture properties of steel fiber reinforced cement-based composites are improved to a great extent,and the different fiber distribution have little influence on fracture parameters of the steel fiber cement-based composites.(3)To study the fracture properties of aligned steel fiber reinforced cement-based composites,a non-linear hinge model was used.Combined with the three-point bending beam test,the method of this paper was validated.At the same time,research the influence of model parameters on the model.And predict the larger size fracture properties of aligned steel fiber reinforced cement-based composites.(4)The size effect of aligned steel fiber cement-based composites was studied by comparing the calculation of strength,flexural toughness and other parameters.It was shown that the nominal strength and flexural toughness of aligned steel fiber cement-based composites have certain size effect.However,the size effect is not obvious.