RESEARCH ON MECHANICAL PROPERTIES OF RECYCLED CONCRETE USING DIFFERENT RECYCLED COARSE AGGREGATE REPLACEMENT

In order to research mechanical properties and failure mechanism of recycled concrete with different recycled coarse aggregate replacement rate. Using waste concrete as recycled coarse aggregate，33 standard cubes，33standard prisms and 33 prisms ( 150 mm 150 mm 550 mm) were made as recycled concrete specimens，whose replacement rate changed from 0% to 100%，level difference was 10%. Through the test，the relationships among replacement rate and the mechanical properties indexes of cube compressive strength，axial compressive strength，flexural strength，strain ductility coefficient，energy dissipative coefficient，secant stiffness and damage degree of the recycled concrete were obtained. The research results showed that with increasing replacement rate，cube compressive strength and axial compressive strength of recycled concrete presented increasing trend. Flexural strength presented decreasing first and then increasing trend. Elastic modulus also presented decreasing trend. Ductility，energy dissipation and stiffness presented decreasing trend; secant stiffness and damage degree of the recycled concrete had the same trend as natural concrete. Considering comprehensively the basic mechanics and economic performance index，it was suggested that 30% ～ 40% should be taken the optimal replacement rate.