Study On Bond And Slip Properties Of Partially Coated Recycled Concrete

The bond slip test was designed by designing 18 sections of partially wrapped recycled concrete short columns.The displacement control method was used to observe the damage and the field test phenomenon of the test piece during the loading process to explore the partially wrapped recycled concrete.The mechanism of bond-slip failure of short-column specimens;the main factors affecting the bond-slip performance of partially-recycled recycled concrete short columns with the replacement ratio of recycled coarse aggregate,concrete strength grade,length of embedded steel and connecting rod spacing The different conditions of the bond-slip performance of the part;at the same time,the load-slip curve,the bond stress-slip curve and the bond-slip characteristic value and the average bond of the partially-recycled recycled concrete specimen obtained by the joint test in the bond slip test The strength is used to study the bond slip strength formula of the test piece and its bond slip constitutive relation.The research results show that the test specimens of partially wrapped recycled concrete short columns have experienced four basic stages in the process of launching,namely micro-slip section,ascending section,descending section and residual section;reclaimed coarse aggregate replacement rate,concrete strength grade,The embedded length of the steel and the distance between the connecting rods are important factors influencing the bond strength and the bond-slip characteristics of the partially-recycled recycled concrete specimens.The bond strength and the bond-slip characteristics of the specimens are different with different influencing factors.The variation law,the replacement ratio of recycled coarse aggregate,the strength grade of concrete,the length of embedded steel and the spacing of the connecting rod are different.The bonding strength and the bonding slip characteristics are different.In general,the smaller the connecting rod spacing,The bond strength of the partially-recycled recycled concrete specimens is higher.When the replacement ratio of recycled coarse aggregates is 0 and 50%,the residual bond strength of the specimens with concretestrength grade C30 is higher than C40.According to the design parameters of the test piece and the measured data values,the regression equations of the bond strength and the bond-slip characteristics are derived.The constitutive relationship of the bond-slip formula is divided into four segments,which are also micro-slip segments,ascending segments,and descending.The segment and the residual segment,the micro-slip segment and the ascending segment exhibit a linear trend,and the descending segment exhibits a hyperbolic situation,and the development trend of the residual segment is close to a horizontal straight line.