RESEARCH ON THE MIX PROPORTION OF THE LAYER CARBON FIBER AND POLYPROPYLENE FIBER CONCRETE BASED ON THE CURRENT ROTATING COMBINATION DESIGN

Some mix tests were carried out for the main factors that effect the 28 d mechanical properties of the layer carbon fiber and polypropylene fiber concrete,such as water-binder ratio,the content of fly ash,the content of the polypropylene fiber and the content of the carbon fiber;then a mathematical model was set up and the optimal mix was determined through the secondary regressive rotating combination design of four factors.The result shows that quadratic polynomial regression model can be used to establish the regression equation of the 28 d compressive strength and flexural strength of the layer carbon fiber and polypropylene fiber conrete.When the water-binder ratio is 0.3,the content of fly ash,the content of the polypropylene fiber and the carbon fiber are zero,the 28 d compressive strength of the layer carbon fiber and polypropylene fiber can reach the maximum 68.21 MPa;while the four factors respectively are 0.3,0,1.2% and 1.6%,the maximum 28 d flexural strength is 8.84 MPa.The effect of polypropylene fiber and the layer carbon fiber on the concrete compressive strength is little,but significant on the concrete flexural strength.