Study On Mechanical Behaviors Of Composite Slabs Filled With Demolished Concrete Blocks

It is indicated that the concrete structural members filled with demolished concreteblocks (DCBs) are new effective approaches of recycling demolished concrete, and ownprofound development potentials. Series research of basic behaviors and(or) seismicbehaviors on beam, column, wall, joint are carried out by our research group. On this basis, inorder to expand the variety of concrete structural members filled with DCBs, the followingresearch work are involved in this paper:A total of ten composite slabs filled with DCBs were tested for their mechanicalproperty. The influences of some factors, such as repalcement ratio of DCBs, shear span andslab thickness, on the horizontal shear-bond behavior of these specimens were investigated.Based on the combined strength of the cast-in-situ concrete (CC) and DCBs, a formula wasproposed for horizontal shear-bond capacity of composite slabs filled with DCBs. Resultsshow that: when the repalcement ratio of DCBs within a range of21%-36%, the difference ofhorizontal shear-bond capacity, between composite slabs only filled with CC and these filledwith DCBs, is-14.5%~13%; the horizontal shear-bond capacity of composite slabs filled withDCBs is changed non-monotonically with increasing repalcement ratio.Six mechanical tests of composite slabs filled with DCBs, anchored by stud at the end,were carried out. Influences of some parameters (such as repalcement ratio of DCBs, the studarrangement) on the bending property were investigated. Based on the combined strength ofthe CC and DCBs, the bending capacity of the specimens were calculated, according to thecurrent formulas for composite slabs, and compared with the measured results. Results showthat: the initial stiffness of the specimens filled with DCBs is almost the same with that of thespecimen only filled with CC; the bending capacity of all the specimens filled with DCBs is alittle larger than that only filled with CC.Base on ABAQUS, numerical simulation on the horizontal shear-bond behavior forabove specimens without studs was carried out, and compared to test results. Base on theprevious research achievements, and considering a reduction of shear-bond strength due tovertical separation between sheeting and concrete, a reasonable bond-slip model waspresented. It indicate that: the horizontal shear-bond capacity and initial stiffness of the specimens by FEM agree well with the test results; so a effective model is proposed.