Mechanical test and constitutive model of recycled plastic fiber reinforced recycled concrete

Abstract

• The uniaxial compression test, quasi-triaxial compression test and flexural tensile test of RPFRRC are carried out. • The compressive and flexural tensile strength of the RAC can be improved by adding recycled plastic fibers. • The confining pressure and the fiber volume ratio have obvious effects on the stress-strain curve of RPFRRC. • A three-dimensional constitutive model of RPFRRC is proposed. • The rationality of the improved model is verified by the experimental data of quasi-triaxial compression test. The use of the Recycled Plastic Fiber Reinforced Recycled Concrete (RPFRRC) can not only improve the mechanical properties of concrete, but it also can reuse the waste. The uniaxial compression test, quasi-triaxial compression test and bending-tension test of RPFRRC are carried out. Experimental results show that the compressive and flexural tensile strength of the RPFRRC can be improved by adding an appropriate content of recycled plastic fibers. For constant fiber content, the fiber length has a great influence on the compressive strength and flexural tensile strength of the RPFRRC. The confining pressure and the fiber volume ratio have a relatively large influence on the stress-strain curve of RPFRRC specimens. Considering the shortcomings of the Ottosen model, a three-dimensional constitutive model which is suitable for describing the triaxial compressive stress-strain relationship of RPFRRC is proposed. This model uses the improved equation as the equivalent uniaxial equation for the three-dimensional stress state of fiber reinforced concrete. The quasi-triaxial compression test data of the RPFRRC shows that the improved model is more consistent with the test results than the Ottosen model. The experimental data of other fiber reinforced concrete also verify that the improved model proposed in this paper is reasonable.